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1
IMIETE, IIKPOEMUGH ELO. « Light Weight Polysaccharides as biofillers for Elastomeric Compounds ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/313695.
Texte intégralRésumé :
I pneumatici sono realizzati aggiungendo riempitivi alla matrice polimerica. Insieme ad altri additivi, le mescole per pneumatici vengono polimerizzate e modellate. I riempitivi convenzionali utilizzati nel processo sono nerofumo e silice. A causa delle preoccupazioni ambientali associate all'uso di questi riempitivi, in questo lavoro sono stati esplorati polisaccaridi leggeri derivati da fonti biologiche come possibile sostituzione. I riempitivi utilizzati in questo progetto erano nanocristalli di cellulosa e alfa 1,3 glucano. La loro chimica superficiale è simile a quella delle cariche di silice aventi abbondanti gruppi idrossilici superficiali. Questi bio-riempitivi sono idrofili e non compatibili con la matrice polimerica idrofobica come la gomma naturale. A questo proposito, sono stati modificati per essere compatibili con la matrice polimerica.
Per ottenere questa modifica, sono stati impiegati due silani: TESPD, APS essendo silani alifatici e SID, SIB essendo silani ciclici. Tutti i composti sono stati confrontati con i composti di silice come riferimento. I risultati ottenuti con queste cariche hanno mostrato che i silani APS favoriscono una vulcanizzazione molto rapida e aumentano la densità di reticolazione. Con questo silano, è stato ottenuto un modulo di stoccaggio più elevato e le proprietà erano migliori rispetto ai composti di silice di riferimento. Lo svantaggio riscontrato con APS è il fatto che una grande quantità di silano influisce sulle proprietà di trazione. Il meccanismo di reazione osservato per i composti TESPD rivela che il modulo di conservazione dei composti con questo silano potrebbe non essere paragonabile a quello di APS, ma le proprietà di trazione erano notevolmente superiori. La decisione su quali silani da utilizzare sarebbe quindi collegata alle proprietà attese che è di interesse.
Quando sono stati esplorati i silani ciclici, la loro natura reattiva ha reso la vulcanizzazione veloce. Molto interessante il rinforzo delle varie mescole. Tuttavia, è stato osservato che a un basso carico di silano compreso tra il 2-5%, le proprietà rimangono pressoché le stesse anche quando le quantità di silano sono state aumentate fino al 12%. Infatti, la quantità di silani ciclici superiore al 5% rendeva il materiale fragile e produceva proprietà di trazione molto inferiori. Si consiglia quindi di preparare la carica polisaccaridica con bassissime quantità di silani ciclici.
Le modifiche con i silani sono state esplorate in quanto è ampiamente utilizzato nell'industria dei pneumatici. In alternativa, è stata studiata anche una modifica enzimatica verde che utilizza le lipasi come catalizzatore. La procedura sviluppata in questo lavoro è stata semplificata con la possibilità di recuperare tutto il filler utilizzato nella reazione e il riutilizzo di altre specie reagenti. Il concetto in questa modifica era quello di innestare porzioni che possono servire per idrofobizzare la superficie e successivamente promuovere una reticolazione diretta tra il riempitivo e la gomma. Il nanocristallo di cellulosa è stato il riempitivo di questa modifica e sulla superficie sono stati innestati gruppi acetile e metacrilato. Quando i composti sono stati preparati con il CNC modificato, le proprietà erano molto interessanti. In effetti, erano migliori della silice di riferimento. I risultati ottenuti in questo processo sono molto promettenti, soprattutto se si considera il futuro dell'industria dei pneumatici.
Il glucano è un nuovo concorrente nel mondo dei biofiller per l'industria dei pneumatici, è ancora in fase di studio per accertarne l'idoneità. I composti realizzati con glucano utilizzando silani hanno mostrato che alcuni aspetti delle proprietà sono inferiori alla silice di riferimento. In termini di composti verdi e proprietà di vulcanizzazione, era relativamente migliore del composto di silice.Tires are made by adding fillers to polymeric matrix. Alongside other additives, the tire compounds are cured and shaped. The conventional fillers used in the process is carbon black and silica. Owing to the environmental concerns associated with the use of these fillers, lightweight polysaccharides derived from bio sources were explored in this work as possible replacement. The fillers that were used in this project were cellulose nanocrystals and alpha 1,3 glucan. Their surface chemistry is like that of silica fillers having abundant surface hydroxyl groups. These bio fillers are hydrophilic and not compatible with hydrophobic polymer matrix such as natural rubber. In this regard, they were modified to be compatible with the polymeric matrix. To achieve this modification, two silanes were employed: TESPD, APS being aliphatic silanes and SID, SIB being cyclic silanes. All the compounds were compared with silica compounds as reference. The results obtained with these fillers showed that the APS silanes promote very fast vulcanization and increases the crosslinking density. With this silane, a higher storage modulus was achieved, and properties were better than the reference silica compounds. The drawback that was experience with APS is the fact that large amount of the silane affects the tensile properties. The reaction mechanism observed for TESPD compounds reveals that the storage modulus of the compounds with this silane may not be comparable to that of APS but the tensile properties were remarkably higher. Deciding on which silanes to be used would therefore connect with the expected properties that is of interest. When the cyclic silanes were explored, their reactive nature made the vulcanization to be fast. The reinforcement of the various compounds was very interesting. However, it was observed that at low silane loading between 2-5%, the properties remain fairly the same even when the silane amounts were increased up to 12%. In fact, the cyclic silanes amount exceeding 5% made the material brittle and resulted in very inferior tensile properties. It is therefore advisable to prepare the polysaccharides filler with very low amount of cyclic silanes. The modifications with silanes were explored as it is heavily used in the tire industry. Alternatively, a green enzymatic modification using lipases as catalyst was also investigated. The procedure developed in this work was simplified with the possibility of recovering all the filler used in the reaction and the reuse of other reacting species. The concept in this modification was to graft moieties that can serve to hydrophobized the surface and subsequently promote a direct crosslinking between the filler and rubber. The cellulose nanocrystal was the filler for this modification and acetyl and methacrylate groups were grafted on the surface. When compounds were prepared with the modified CNC, the properties were very interesting. In fact, they were better than the reference silica. The results obtained in this process are very promising especially when the future of the tire industry is considered. Much attention was given to cellulose nanocrystals compared to alpha 1,3 glucan. Although glucan is a new entrant into the biofiller world for the tire industry, it is still being studied to ascertain their suitability. The compounds made with glucan using silanes showed that some aspects of the properties are lower that the reference silica. In terms of the green compounds and vulcanization properties, it was relatively better than silica compound. But when glucan compounds were vulcanized, the reinforcements and tensile properties were observed to be lower than silica compounds. It is obvious that more treatment, processing methods and the use of vast alternative modification strategy is needed to prepare glucan for improved properties and possible use in tire compounds.
2
Oliveira, Aline Cristina Maia de [UNESP]. « Avaliação dos parâmetros de processo de reticulação do polietileno de baixa densidade ». Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/94445.
Texte intégralRésumé :
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oliveira_acm_me_guara.pdf: 813696 bytes, checksum: 291a32b0707aad7bbcf67e98ead0311c (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O presente trabalho aborda as condições de reticulação do polímero termoplástico polietileno e, para isso, foram avaliadas diferentes temperaturas de processo (60 e 90°C), bem como diferentes tempos de permanência em imersão em banho termostatizado (1, 3, 6 e 9 horas). Esta avaliação foi realizada a partir dos ensaios de teores de gel e fator de uptake, de massa específica, de calorimetria exploratória diferencial (DSC), de análise termogravimétrica (TGA), de espectrofotometria no infravermelho com transformada de Fourier (FT-IR) e de ensaios de tração. Desta forma, o grau de reticulação do polietileno de baixa densidade reticulado em água, foi correlacionado com sua morfologia, com seu desempenho térmico e mecânico. Os resultados mostraram que o teor de gel do polietileno reticulado aumentou com o aumento da temperatura e do tempo de exposição desta matriz polimérica em água, sendo que, este aumento ocorreu de forma significativa até 3 horas de exposição, não sendo observados ganhos significativos na formação de ligações cruzadas após este período
The present work deals with the crosslink conditions of polyethylene polymer using different process temperatures (60 and 90°C). For this different water immersion times in thermostated bath (1, 3, 6 and 9 hours) have been analyzed by using gel content and uptake factor, density tests, dynamic scanning calorimetric analyses (DSC), thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR) and tensile tests. This way, it was evaluated the degree of crosslinking of low density polyethylene crosslinked into water, and these parameters were correlated with the morphology and its thermal and mechanical performance. According to found results, it was observed that the gel content of polyethylene crosslinked increased with increasing of exposition temperature and time of this polymeric matrix in water, therefore, this increase was significantly up to 3 hours of exposition, not being observed significant gains in crosslinking density after this time
3
Oliveira, Aline Cristina Maia de. « Avaliação dos parâmetros de processo de reticulação do polietileno de baixa densidade / ». Guaratinguetá : [s.n.], 2011. http://hdl.handle.net/11449/94445.
Texte intégralRésumé :
Resumo: O presente trabalho aborda as condições de reticulação do polímero termoplástico polietileno e, para isso, foram avaliadas diferentes temperaturas de processo (60 e 90°C), bem como diferentes tempos de permanência em imersão em banho termostatizado (1, 3, 6 e 9 horas). Esta avaliação foi realizada a partir dos ensaios de teores de gel e fator de uptake, de massa específica, de calorimetria exploratória diferencial (DSC), de análise termogravimétrica (TGA), de espectrofotometria no infravermelho com transformada de Fourier (FT-IR) e de ensaios de tração. Desta forma, o grau de reticulação do polietileno de baixa densidade reticulado em água, foi correlacionado com sua morfologia, com seu desempenho térmico e mecânico. Os resultados mostraram que o teor de gel do polietileno reticulado aumentou com o aumento da temperatura e do tempo de exposição desta matriz polimérica em água, sendo que, este aumento ocorreu de forma significativa até 3 horas de exposição, não sendo observados ganhos significativos na formação de ligações cruzadas após este períodoAbstract: The present work deals with the crosslink conditions of polyethylene polymer using different process temperatures (60 and 90°C). For this different water immersion times in thermostated bath (1, 3, 6 and 9 hours) have been analyzed by using gel content and uptake factor, density tests, dynamic scanning calorimetric analyses (DSC), thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR) and tensile tests. This way, it was evaluated the degree of crosslinking of low density polyethylene crosslinked into water, and these parameters were correlated with the morphology and its thermal and mechanical performance. According to found results, it was observed that the gel content of polyethylene crosslinked increased with increasing of exposition temperature and time of this polymeric matrix in water, therefore, this increase was significantly up to 3 hours of exposition, not being observed significant gains in crosslinking density after this time
Orientador: Edson Cocchieri Botelho
Coorientador: Antonio Fernando Branco Costa
Banca: Luiz Claudio Pardini
Banca: Michelle Leali Costa
Mestre
4
Niedermayer, Wolfgang. « Auf dem Wege zu einem Disilin RSi≡SiR Supersilylierte Silane, Silanide, Silylene, Disilene ». Diss., lmu, 2000. http://nbn-resolving.de/urn:nbn:de:bvb:19-2914.
Texte intégral
5
Garcia, Bruno Pienis. « Associação de taninos e silano na passivação de aço galvanizado ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/165150.
Texte intégralRésumé :
A proteção contra a corrosão do aço galvanizado com um tratamento via cromatização, apesar de apresentar desempenho superior à outras alternativas, gera efluentes tóxicos ao meio ambiente e em especial aos seres humanos. Dentre as alternativas apresentadas até o presente momento, que incluem diversos tipos de tratamentos para esse substrato, um deles é o revestimento com silanos. Apesar desse revestimento ter um satisfatório desempenho, vem se utilizando incorporações em seu preparo, para se potencializar seu desempenho. A incorporação escolhida nesse trabalho foi a do tanino, um inibidor de corrosão natural, extraído de vegetais. O objetivo desse trabalho é avaliar um revestimento do silano Ortossilicato de tetraetila (TEOS) junto de um tanino para o aço galvanizado destinado a aplicações onde não há pintura. Essa sinergia deve proteger a superfície até que o zinco consiga de forma natural desenvolver sua pátina protetora, formando uma barreira entre substrato e eletrólito. Foram revestidas chapas de aço galvanizado com períodos de imersão que variaram entre 2 e 10 minutos, com soluções na concentração de tanino de 2g/L e 10g/L com diferentes valores de pH, em uma solução previamente preparada de TEOS em concentração de 2%, água 49% e etanol 49%. Realizou-se análise comparativa entre os diferentes parâmetros de tratamento proposto neste trabalho com aço galvanizado somente desengraxado e aço galvanizado cromatizado nas seguintes técnicas: espectroscopia de impedância eletroquímica, polarização potenciodinâmica, microscopia eletrônica de varredura acoplada a espectroscopia de energia dispersiva, e ensaios de corrosão acelerada em câmara úmida e névoa salina. Os resultados apresentados indicam que diferentes concentrações de tanino e tempos de imersão não são significativos para causar diferenças relevantes entre os desempenhos e que os substratos tratados demonstraram um desempenho superior comparado às amostras que não tinham nenhum tipo de tratamento e inferiores às amostras cromatizadas.The corrosion protection of galvanized steel with a chromatized treatment, despite superior performance to other alternatives, generates effluents toxic to the environment and especially to humans. Among the alternatives presented to date, which include several types of treatments for this substrate, one of them is the coating with silanes. Although this coating has a satisfactory performance, it has been using incorporations in its preparation, to enhance its performance. The incorporation chosen in this work was that of tannin, a natural corrosion inhibitor, extracted from plants. The objective of this work is to evaluate a coating of silane tetraethyl orthosilicate (TEOS) with tannin for galvanized steel, for applications where there is no paint. This synergy should protect the surface until zinc can naturally develop its protective patina, forming a barrier between substrate and electrolyte. Galvanized steel plates were coated with immersion times ranging from 2 to 10 minutes, with solutions at tannin concentration of 2 g/L and 10 g/L with different pH values, in a previously prepared solution of TEOS at a concentration of 2% , 49% of water and 49% of ethanol. A comparative analysis was performed between the different treatment parameters proposed in this work with galvanized steel only degreased and galvanized steel chromatized in the following techniques: electrochemical impedance spectroscopy (EIE), potentiodynamic polarization, scanning electron microscopy coupled to dispersive energy spectroscopy, and corrosion tests accelerated in humid chamber and saline mist. The results indicated that different concentrations of tannin and immersion times are not significant to cause relevant differences between the performances and that the substrates demonstrated superior performance compared to the samples that had no type of treatment, and inferior to the samples chromatized.
6
Murillo, Gomez Fabian de Jesus 1987. « Avaliação da união cerâmica-vítrea/cimento-resinoso usando diferentes soluções contendo silano = Evaluation of glass-ceramic/resin-cement interface using different silane-containing solutions ». [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288150.
Texte intégralRésumé :
Orientador: Mario Fernando de GoesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo deste estudo foi avaliar a interação de diferentes soluções contendo silano, com cerâmica vítrea e cimentos resinosos por meio da resistência de união por microcisalhamento e avaliação morfológica da fratura. Este estudo foi separado em dois capítulos. No capítulo 1 foi verificada a influência de quatro soluções contendo silano (solução convencional, solução convencional seguida da aplicação de um sistema adesivo convencional, sistema adesivo universal contendo silano e um primer universal para materiais cerâmicos contendo silano) e a influência do uso ou não do condicionamento prévio da cerâmica com ácido fluorídrico na resistência de união entre uma cerâmica vítrea e um cimento resinoso convencional, após 24h. A análise morfológica da fratura foi avaliada com microscópio eletrônico de varredura. Todos os dados foram submetidos à análise de variância a dois fatores e teste de Tukey (?=0.05). Os resultados mostraram que o condicionamento prévio da cerâmica com ácido fluorídrico foi um fator determinante na obtenção de valores estatisticamente significativos na resistência de união entre ela e o cimento resinoso. A solução de silano convencional foi o único tratamento que proporcionou valores significativamente maiores de resistência de união sem a aplicação do condicionamento prévio na cerâmica vítrea. Todas as soluções proporcionaram resistência de união estatisticamente superior quando o ácido fluorídrico foi usado previamente em relação ao grupo de cerâmicas só jateadas com óxido de alumínio. Os valores foram diferentes estatisticamente entre as soluções, sendo a solução convencional de silano a mais efetiva. Padrão de fratura coesiva no cimento foi associado com valores maiores, enquanto que falha adesiva foi associada com menor resistência de união. No capítulo 2, o objetivo foi avaliar a interação das mesmas soluções contendo silano com cinco cimentos resinosos, três convencionais (Rely X Ultimate, Rely X ARC e Variolink II) e dois autoadesivos (Bifix e Rely X Unicem 2). A resistência de união por microcisalhamento e o tipo de fratura foram avaliados. Os valores foram submetidos à análise estatística a dois fatores e ao teste de Tukey (?=0.05). Os resultados mostraram que a resistência de união foi maior quando a cerâmica foi tratada com a solução convencional de silano para todos os cimentos. A maioria dos cimentos apresentou resistência de união sem diferença estatística quando usados junto com o sistema adesivo universal e o primer cerâmico, exceto para o Bifix e Rely X ARC. Nas fotografias em MEV observaram-se áreas de polimerização incompleta nos casos do Bifix e Rely X ARC. Os grupos com melhor resistência de união apresentaram maior prevalência de fratura coesiva no cimento, enquanto que os grupos com menores valores de resistência de união apresentaram maior prevalência de fraturas adesivas e maior variabilidade do tipo de falha no mesmo grupo. Como conclusão observou-se que as soluções que combinam silano com outros componentes podem melhorar a adesão entre a cerâmica vítrea e o cimento resinoso sempre que utilizadas em cerâmicas vítreas previamente condicionadas, mas o seu efeito positivo é menor do que o obtido pela solução convencional de silano. Além disso, a interação dessas soluções não convencionais com os cimentos resinosos é material dependente já que nem todos os cimentos avaliados foram afetados
Abstract: The aim of this study was to evaluate the interaction of different silane-containing solutions, with glass ceramic and resin cements by performing a µSBS and failure evaluation. This investigation was separated in two chapters. Chapter 1 verified the influence of four silane-containing solutions (conventional solution, conventional solution followed by a conventional adhesive system, silane-containing universal adhesive system and a silane-containing universal ceramic primer) and previous hydrofluoric acid etching on µSBS of glass ceramic and one conventional resin cement after 24 hours storage. Morphological failure analysis was assessed with a scanning electron microscope. All data was submitted to two-way ANOVA and Tukey test (p<0.05). Results showed that hydrofluoric acid etching was determining to increase µSBS. The only solution that increased significantly µSBS mean value without previous hydrofluoric acid etching was the sole-silane solution. All tested solutions increased µSBS when ceramic was previously etched but with statistical differences between them, being the most effective the sole-silane solution. Cohesive failure in resin cement was associated with higher µSBS values, while ceramic/cement adhesive failure was correlated to lower mean values. In chapter 2 the purpose was to evaluate the interaction of the same silane solutions with five resin cements, three conventional (Rely X Ultimate, Rely X ARC e Variolink II) and two self-adhesive (Bifix e Rely X Unicem 2). Also µSBS test and failure evaluation were performed and results analyzed by ANOVA two-way and Tukey test (p<0.05). Results showed that µSBS was higher when ceramic was treated with the sole-silane solution for all cements. Most of cements showed statistically similar mean values when treated with the universal adhesive and the universal ceramic primer with the exception of BiFix and RelyX ARC. SEM images revealed some incomplete polymerization areas for those cases. Likewise groups that performed better showed more prevalence of cohesive failure in resin cement while groups that presented lower mean values showed more prevalence of adhesive failure and more failure type variability. As conclusion, it was observed that solutions combining silane with other components could improve adhesion between glass ceramic and resin cement whenever employed on previously conditioned ceramics, but their positive effect is lower than the one produced by the sole-silane solution. Furthermore, interaction of those non-conventional silane-solutions with resin cements may be material dependent as not all cements tested were negatively affected
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários
7
Bertuoli, Paula Tibola. « Desenvolvimento e caracterização de uma tinta em pó base poliéster contendo montmorilonita funcionalizada com silano ». reponame:Repositório Institucional da UCS, 2014. https://repositorio.ucs.br/handle/11338/826.
Texte intégralRésumé :
Dentre os métodos empregados para a proteção à corrosão de materiais metálicos os
revestimentos orgânicos vêm sendo muito utilizados devido a sua facilidade de aplicação e
custos razoáveis. A propriedade de barreira dos revestimentos orgânicos pode ser melhorada
com a incorporação de cargas adequadas, tais como nanocargas que, mesmo em baixas
concentrações, apresentam propriedades de barreira superiores às cargas convencionais. A
montmorilonita (MMT) é a fase inorgânica mais utilizada na obtenção de nanocompósitos
poliméricos. Para melhorar a compatibilidade e dispersão da argila na resina polimérica,
muitos pesquisadores têm realizado o processo de funcionalização da argila utilizando silano.
O presente trabalho tem como objetivo desenvolver e caracterizar uma tinta em pó base
poliéster contendo diferentes teores da argila montmorilonita sódica (MMT-Na+) modificada
com o silano 3-aminopropiltrietoxisilano (γ-APS). A argila modificada com silano (S-MMT)
ou a MMT-Na+ foi incorporada numa formulação padrão de tinta em pó base poliéster nas
proporções de 2, 4 e 8% (m/m). A incorporação da argila na tinta ocorreu no estado fundido
(extrusão). As argilas, a tinta em pó e o revestimento após a cura foram analisados
empregando diferentes técnicas de caracterização, tais como difração de raios X (DRX),
espectroscopia de infravermelho por transformada de Fourier (FTIR), análise
termogravimétrica (TGA), calorimetria exploratória diferencial (DSC), microscopia eletrônica
de varredura (MEV), microscopia óptica (MO). As tintas em pó foram aplicadas sobre painéis
de aço carbono por pulverização eletrostática. O efeito da incorporação de diferentes teores da
argila modificada e não modificada nas propriedades físicas e de proteção à corrosão das
tintas foram avaliadas empregando ensaios de medida de brilho, aderência, flexibilidade,
resistência ao impacto, potencial de circuito aberto (OCP), imersão, impedância eletroquímica
(EIS) e exposição à névoa salina. Através do DRX foi confirmada a modificação e a
intercalação de uma bicamada de moléculas de aminopropil no espaçamento interlamelar da
argila. A S-MMT apresentou uma maior perda de massa do que a MMT-Na+ devido à
presença de silano na sua estrutura. A MMT-Na+ se apresentou na forma de grandes
aglomerados irregulares que se tornaram menores e mais finos após sua modificação com
silano. Nas tintas contendo os diferentes teores de argila (MMT-Na+ ou S-MMT) não foi
constatada a esfoliação da argila, sendo obtido um microcompósito. A partir da caracterização
térmica da tinta em pó constatou-se que os revestimentos contendo a S-MMT apresentaram
menor estabilidade térmica que os demais revestimentos devido à presença do modificador
orgânico. A presença da argila MMT-Na+ ou S-MMT (com exceção de 4% (m/m) da
S-MMT) reduziu a energia liberada no processo de reticulação. Para todos os revestimentos
contendo argila foi constatado o aumento da dureza superficial do revestimento e a redução de
brilho com o aumento do teor de argila, sendo este efeito mais pronunciado com a adição de
8% (m/m) de MMT-Na+. A aderência do revestimento ao substrato e a flexibilidade do
revestimento não foram alteradas pela presença da argila, porém os revestimentos contendo a
S-MMT apresentaram melhores resultados quanto à resistência ao impacto que os
revestimentos contendo a argila MMT-Na+. Tanto nos ensaios eletroquímicos como no de
exposição à névoa salina a modificação da argila com o silano resultou em revestimentos com
melhor desempenho à corrosão que os revestimentos contendo a argila não modificada.
Contudo, a propriedade de proteção à corrosão dos revestimentos contendo argila não foi
superior ao revestimento isento de argila.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2014-08-25T19:29:58Z No. of bitstreams: 1 Dissertacao Paula Tibola Bertuoli.pdf: 5722201 bytes, checksum: cbb4f785db0e5a8566d49614c04b7264 (MD5)
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Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS
Among the methods used for corrosion protection of metal materials the organics coatings have been widely used due to their ease of application and reasonable costs. The barrier property of the organic coatings can be improved by incorporation of appropriate fillers such as nanofillers that even in low concentrations show superior barrier properties to conventional fillers. The montmorillonite (MMT) is the inorganic phase more used to prepare polymer nanocomposites. To improve the compatibility and dispersion of the clay in a polymer resin, many researchers have performed the functionalization process of the clay using silane. This study aims to develop and characterize a polyester based powder coating containing different amounts of sodium montmorillonite (MMT-Na+) modified with the silane 3-aminopropyltriethoxysilane (γ-APS). The clay modified with silane (S-MMT) or MMT-Na+ clay were incorporated into a standard commercial formulation of a polyester based powder coating on the ratios of 2, 4 and 8 wt%. The incorporation of clay into the paint was in the molten state (extrusion). The clays, the powder coating and coating after curing were analyzed using different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and optical microscopy (MO). The powder coatings were applied on carbon steel panels by electrostatic method. The effect of incorporating different amounts of modified and unmodified clay on the physical properties and corrosion protection of the coatings obtained were evaluated using techniques such as gloss measurement, adhesion, flexibility, impact resistance, open circuit potential (OCP), immersion and electrochemical impedance spectroscopy (EIS) in sodium chloride solution and exposure to salt spray. XRD results confirmed the modification and intercalation of a bilayer of aminopropyl molecules in the interlayer spacing of the clay. By thermal analysis the S-MMT clay showed greater loss greater than the MMT-Na+ clay due to the presence of silane in their structure. The MMT-Na+ are presented in the form of large irregular agglomerates that have become smaller and thinner after its modification with silane. In the coatings obtained by incorporating different concentrations of MMT-Na+ or S-MMT it was not detected the exfoliation of clay, characterizing a microcomposite. Through of the thermal characterization of the powder paint it was found that the coatings containing S-MMT clay showed lower thermal stability than other coatings due to the presence of the organic modifier. The presence of MMT-Na+ or S-MMT clay (except 4 wt% of S-MMT clay) reduced the energy released in the process of crosslinking. The surface hardness of the coating was increased and the brightness was decreased with increasing clay content and this effect was most pronounced with the addition of 8 wt% of MMT-Na+. The adhesion of the coating to the substrate and the flexibility of the coating were not changed by the presence of clay, but the clay coatings containing S-MMT showed better results than coatings containing MMT-Na+ regarding the impact resistance. Both electrochemical and exposure to salt spray tests the silane modified clay resulted in coatings with better corrosion performance than those coatings containing the unmodified clay. However, the corrosion protection of the coatings containing montmorillonite was not superior to the coating free of clay.
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Mudry, Guillermo Alejandro. « Revestimentos de silanos obtidos sobre aço carbono e sua utilização como agentes promovedores de adesão em uniões aço-resina epóxi ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/61013.
Texte intégralRésumé :
A utilização de silanos como agentes promovedores de adesão demonstrou ser uma solução útil para a união entre materiais dissimilares, incrementando a adesão e aumentando inclusive a resistência a corrosão entre os mesmos . A utilização destes agentes como promovedores de adesão, sobre diferentes combinações de materiais, continua sendo estudada atualmente. Este trabalho teve como objetivo avaliar a capacidade de diferentes tipos de silanos como agentes promovedores de adesão. tanto funcionais como não funcionais, na união entre aço SAE 1060 e resina epóxi. Para isto, foram primeiramente obtidos filmes de silano sobre amostras de aço através de diferentes tratamentos. Estes filmes obtidos foram caracterizados por meio de diferentes técnicas. Foram realizados testes de aderência através do método especificado pela norma ASTM D3359 para avaliar a resistência de adesão dos diferentes filmes ao substrato. As amostras testadas foram analisadas através de microscopia eletrônica de varredura (MEV). Também, foram realizadas análises de espectroscopia de energia dispersiva (EDS) sobre as mesmas amostras, permitindo obter outras características dos filmes de silano formados. Os tratamentos que apresentaram melhores resultados na caracterização em MEV/EDS foram escolhidas para a preparação dos corpos de prova de uniões com resina epóxi. Estas uniões foram utilizadas para realizar testes de adesão do tipo arrancamento de modo a avaliar o efeito dos tratamentos com silano na resistência de adesão da união entre o substrato de aço e a resina epóxi. Os resultados dos testes de arrancamento permitem afirmar que existe uma melhoria na resistência de adesão com um dos tratamentos com silano sobre o substrato de aço seguido de revestimento com resina epóxi. A utilização de tratamentos com silanos mostram-se promissoras para esta aplicação.The use of silanes as adhesion enhancer agent proved to be a useful solution for the union of dissimilar materials, increasing the bond strength between them, also increase the corrosion resistance. The use of these agents as adhesion enhancer, with different materials combination, is still being studied today. The aim of this work was to evaluate the ability of different silanes as adhesion agent promoters in joints of SAE 1060 steel and epoxy resin; both functional and not functional silanes. At the beginning and for this purpose were different types of treatments used to obtain silane films on steel samples. Different techniques were used to characterize these films. To evaluate the bond strength adhesion test where performed according to the ASTM D3359 standard. Samples were analyzed with scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDX) analyses were also performed on the same sample allowing to obtain others characteristics of the silane films formed. The treatments that have shown a better performance in the SEM/EDX analyses were selected to make steel and epoxy resins joint samples. These specimens were used to perform pull-out type adhesion test to evaluate the effect of the silanes treatments in the bond strength of steel and epoxy resin joints. The results of de pull-out test indicate that the use of silane improves the bond strength of steel and epoxy resin joints. The use of silane treatments has shown promising results for this application.
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Queiroz, Daniely Ferreira de. « Nanopartículas magnéticas de ferritas recobertas com sílica e funcionalizadas com vinil silano ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-04082017-153036/.
Texte intégralRésumé :
Com o desenvolvimento da nanociência e da nanotecnologia, as nanopartículas magnéticas vêm sendo cada vez mais gerado interesse devido as inúmeras possíveis aplicações na área de catálise, diagnóstico, pigmentos, sensores, etc. Atualmente, as nanopartículas com potencialidade de aplicação em biomedicina que pode se destacar os as ferritas magnéticas os quais apresentam comportamento superparamagnético a temperatura ambiente. Além dos ligantes funcionais, as nanopartículas magnéticas são geralmente recobertas com polímeros orgânicos ou inorgânicos, destacando-se a sílica, nessa última classe. O sistemas as nanopartículas magnéticas recobertas com sílica formando um sistema casca-caroço, possibilita que o núcleo magnético se mantenha protegido por uma camada polimérica que pode conter grupos funcionais ativos, formando hidridos orgânicos-inorgânicos que devido a sua propriedade hidrofóbica ou hidrofílica dependendo da natureza do ligante de modificação de superfície. Este trabalho foi desenvolvido com intuito de obter nanopartículas magnéticas de ferrita MFe2O4, com (M= Fe, Co, Ni e Cu) com controle de tamanho, forma, composição química e estrutural, dos quais foram sintetizados pelo método de decomposição térmica utilizando diferente precursores metálicos para adequação das melhores condições de síntese. As ferritas magnéticas foram recobrimento com sílica, modificando da superfície da partícula e possibilitando caráter hidrofílico ao sistema casca-caroço, apresentando uma melhor estabilidade coloidal em dispersão aquosa devido a presença de grupos silanois na superfície, bem como uma recobrimento uniforma com apenas um núcleo magnético sem formação de aglomerados. A funcionalização com o grupo o trietoxivinilsilano, através de reações de condensação via catálise básica ou ácida, formou uma rede polimérica Si-O-Si, sendo que a presença do grupo vinil (-CH=CH2) livre na a superfície do sistema casca-caroço foi evidenciado através da técnica de FTIR. Portanto foi possível a obtenção de um sistema hibrido orgânico-inorgânico com a superfície contendo grupo que podem ser reativos, abrindo a possibilidade da utilização deste material para futuros testes de aplicações como sensor multifuncional.In recent decades the development of nanoscience and nanotechnology, magnetic nanoparticles have been increasingly generated interest due to the numerous possible applications in the field of catalysis, diagnosis, pigments, sensors, etc. Currently, the nanoparticles with potential of application in biomedicine that can stand out the magnetic ferrites which have superparamagnetic behavior at room temperature. In addition to the functional binders, magnetic nanoparticles are generally coated with organic or inorganic polymers, especially silica in the latter class. The magnetic nanoparticle systems covered with silica forming a shell-core system allow the magnetic core to remain protected by a polymeric layer that may contain active functional groups, forming organic-inorganic hydrides that due to its hydrophobic or hydrophilic property depending on the nature of the surface modifying binder. This work was developed to obtain magnetic nanoparticles of MFe2O4 ferrite, with (M = Fe, Co, Ni and Cu) control of size, shape, chemical and structural composition, of which were synthesized by the thermal decomposition method using different precursors to suit the best conditions of synthesis. The magnetic ferrites were coated with silica, modifying the surface of the particle and allowing a hydrophilic character to the shell-core system, presenting a better colloidal stability in aqueous dispersion due to the presence of silane groups on the surface, as well as a uniform coating with only one magnetic core without formation of agglomerates. The functionalization with the triethoxyvinylsilane group, through condensation reactions via basic or acid catalysis, formed a Si-O-Si polymer network, and the presence of the free vinyl group (-CH=CH2) on the shell surface was observed by FTIR technique. Therefore, it was possible to obtain an organic-inorganic hybrid system with the surface containing the reactive group, opening the possibility of using this material for tests of future applications as multifunctional sensor.
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Gau, David. « Synthèse et réactivité des sila-ylures de phosphonium ». Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1460/.
Texte intégralRésumé :
L'objectif principal de cette thèse est l'étude d'espèces siliciées hautement réactives stabilisées par coordination d'un ligand phosphine. Dans un premier chapitre, une étude bibliographique permet de faire le point sur les différents modes de stabilisation des silylènes ainsi que sur leurs propriétés chimiques. Le deuxième chapitre concerne la synthèse d'un sila-ylure de phosphonium dont la structure a été déterminée par diffraction des rayons-X. Cette structure est très différente de celles des analogues carbonés, les réactifs de Wittig. En particulier, le centre silicié est fortement pyramidalisé traduisant une absence de délocalisation de la paire libre du silicium contrairement aux ylures de carbone dont la liaison P-C présente un certain caractère [pi]. Le troisième chapitre traite de la réactivité des sila-ylures de phosphonium. Avec un aldéhyde, ils réagissent de façon similaire aux analogues carbonés et la première réaction de type sila-Wittig (formation d'un silène et d'un oxyde de phosphine) a été mise en évidence. Des études mécanistiques (théoriques et spectroscopiques) montrent que le mécanisme de cette réaction est différent de celui de la réaction de Wittig classique. En particulier, la première étape procède via une cyclo-addition [2+1] concertée, sur le centre silicié, démontrant que les sila-ylures de phosphonium se comportent comme des silylénoïdes nucléophiles. Ainsi, des silirènes hypervalents ont été obtenus par réaction avec des acétyléniques via une cyclo-addition [2+1] impliquant le centre silicié. Ces silirènes à température ambiante se réarrangent de façon diastéréosélective pour conduire à des phosphines P-chirales originales. La synthèse d'un disilyne (Si=Si) stabilisé par des ligands phosphines est décrite dans le quatrième chapitre. Ce dérivé réagit à température ambiante avec quatre équivalents de CO2 conduisant à la formation de CO et d'un disilicate original. Dans le dernier chapitre, l'introduction d'un carbène en [alpha] de la fonction sila-ylure nous a permis d'isoler un dérivé à triple liaison Si=C, un silyne, stabilisé par un ligand phosphine. Il s'agit là du premier exemple d'alcyne hybride organique(C)-inorganique(Si). L'étude de sa réactivité montre que le centre carboné de la triple liaison Si=C se comporte comme un carbène singuletThe main objective of this Thesis is the study of highly reactive silicon species stabilised by the coordination of phosphine ligand. In the first chapter, a bibliographic study provides an update on the different methods of stabilising silylene and their chemicals properties. The second chapter concerns the synthesis of a phosphonium sila-ylide whose the structure has been determined by X-Ray diffraction. This structure is very different to those of analogous carbons, the Wittig reactifs. In particular, the silicon center is strongly pyramidalized representing the absence of delocalisation of the silicon lone pair in contrast to the carbon ylides whose the P-C bond present some [pi]-caracters. The third chapter discusses the reactivity of the phosphonium sila-ylides. With an aldehyde, it reacts in a similar way to carbon analogous and the first sila-Wittig reaction (formation of a silene and phosphine oxyde) has been brought to light. Some mechanistic studies (theoretical and spectroscopic) show that the mechanism of this reaction is different from that of a classical Wittig reaction. In particular, the first step proceeds via a [2+1] concerted cyclo-addition, on the silicon center, demonstrating that the phosphonium sila-ylide behave like nucleophilics silylenoïdes. In this way some hypervalentes silirenes have been obtained by reaction of acetylenics compounds via a [2+1] cyclo-addition involving the silicon centre. These silirenes rearrange themselves at room temperature in a diastereoselective way to lead to original P-chirals phosphines. The synthesis of disilyne (Si=Si), stabilised by phosphine ligands is described in the fourth chapter. This compound reacts at room temperature with four CO2 equivalents, to form CO and an original disilicate. In the last chapter, the introduction of a carbene in an [alpha] position of the sila-ylide function allows us to isolate a triple bond derivative Si=C, a silyne which is stabilized by a phosphine ligand. It's the first example of organic(C)-inorganic(Si) hybride alkyne. The study of this reactivity demonstrates that the carbon center of the triple bond Si=C behaves like a singular carbene
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Dvořáková, Martina. « Analýza vlivu celulózových vláken v epoxidovém lepidle určeného pro lepení dřevěných nosných prvků ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227720.
Texte intégralRésumé :
The thesis deals with the properties of epoxy resins, their reinforcing by thermoplastic modified epoxies, rubbers and cellulose fibers. The thesis also describes the production, properties and types of cellulose fibers. In the practical part of this thesis, there was executed reinforcement of epoxy matrix by different amounts of cellulose fibers. Mixing was performed in two ways – by a homogenizer or an ultrasonic homogenizer. There were also executed the tensile strength and shear strength tests to the manufactured conglomerates.
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Santos, Marcia Cristina Gonçalves dos. « Estudo de filmes polimericos contendo silanos y-UPS e VS como revestimentos promotores de adesão em superficies galvanizadas e eletrodepositos de ligas ZN/FE e ZN/Co ». [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263596.
Texte intégralRésumé :
Orientador: Celia Marina de Alvarenga FreireDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia mecanica
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Resumo: A excelente resistência do Zinco em diferentes ambientes corrosivos e sua habilidade em proteger o aço, fazem do aço galvanizado e eletrodepósitos, materiais comuns na indústria automotiva e de construção civil. Os substratos de aço galvanizado e eletrodepósitos de Zinco necessitam, no entanto, ser protegidos em ambientes altamente corrosivos por revestimentos orgânicos (pinturas).A má aderência do sistema Zinco/pintura faz com que a superfície do substrato de Zinco receba um pré-tratamento contendo Cromo relativamente barato e efetivo porém, tóxico ao homem e ao meio ambiente. Filmes poliméricos contendo silanos organofuncionais surgem como alternativa à substituição de pré-tratamento livre de Cromo hexavalente 'CR POT. +6¿, pois são moléculas que podem atuar como agente de acoplamento, promotores de adesão e como protetoras de superfície. A principal vantagem da sua utilização é a promoção da adesão entre materiais orgânicos (pinturas) e inorgânicos (metais). Os sistemas Galvanizado/Silano e Ligas eletrodepositadas/Silano, foram estudados nesta dissertação. Para tanto, técnicas como EIE (Espectroscopia de Impedância Eletroquímica), XPS (Espectrometria Fotoelétrica de Emissão de Raios-X), Ângulo de Contato e análises microscópicas foram utilizadas. A avaliação da resistência por barreira foi feita através da Espectroscopia de Impedância Eletroquímica em solução de 0,1 M de NaCI, comparando-se os desempenhos dos revestimentos. A cura induziu uma modificação importante nos diagramas de impedância, além de outras variáveis, como a concentração, o tempo de hidrólise, os tipos de silano e os substratos diferentes. Os resultados indicaram o Zn/Co revestido por VS e Zn/Fe revestido por 'gama¿-UPS como os sistemas mais promissores
Abstract: The Zinc' s excellent resistance, as used in differents corrosive environments, and its hability to protect steel, make galvanized steel (HDG) and Zinc electrodepositions very usual materiaIs in the automotive and construction industries. Galvanized steel and Zinc electrodepositions substrates need, however, to be protected from strongly corrosive environments by organic coatings (painting). Zinc/paint system weak adhesion results in a relatively cheap and effective zinc substrate pretreatment, however toxic to humam being, and also to the environment. Organofunctional silanes appear as an altemative to substitute this pretreatment, without making use of hexavalent chromium 'CR POT. +6¿), because they are bifuncional molecules that can act as adhesion promoters and surface protectors. The main benefit to employ them is to promote adhesion between organic (painting) and inorganic (metals) materiaIs. The GalvanizedlSilane and Electrodeposition Alloys/Silane systems had been studied in this essay. Techniques like EIS (Electrochemical Impedance Spectroscopy), XPS (X-Ray Emission Photoeletric Spectrometry), Contact Angle and microscopical analyses were used in this work. The barrier for resistance was evaluated through Electrochemical Impedance Spectroscopy in a 0,1M NaCI solution comparing coatings performances. Curing caused as importante modification in the impedance diagrams, as well as other variables like concentration, hydrolysis time, silane types and different substrates. The results indicate the Zn/Co alloy coated for VS and Zn/Fe alloy coated for 'gama¿-UPS as the systems most promising
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Santos, Marcia Cristina Gonçalves dos. « Avaliação do desempenho de filmes contendo silanos e sais de terras raras para proteção contra corrosão de camadas de ZnFe eletrodepositadas ». [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263579.
Texte intégralRésumé :
Orientador: Celia Marina de Alvarenga FreireTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-13T07:27:48Z (GMT). No. of bitstreams: 1 Santos_MarciaCristinaGoncalvesdos_D.pdf: 5280662 bytes, checksum: 763649a5f0d49aa48853a896ab0335c2 (MD5) Previous issue date: 2009
Resumo: Aço galvanizado e aço eletrodepositado com liga ZnFe são materiais comuns na indústria de construção civil e automotiva. Esses materiais à base de zinco necessitam, entretanto, serem protegidos de ambientes corrosivos através de um tratamento de superfície que geralmente contém cromo hexavalente ( Cr6+), tóxico para o meio ambiente e cancerígeno para o homem. O presente trabalho apresenta um estudo com filmes contendo diferentes silanos: viniltrietoxissilano (VS), bis-(1,2-[trietoxissilil] etano) (BTSE) ou bis-(3-[trietoxissilil]-propil? tetrassulfeto (BTESPTS) e nitratos de terras raras (Ce ou La), como revestimentos de conversão para a camada de liga ZnFe. Esses sistemas foram avaliados através das análises de Espectroscopia Fotoelétrica de Emissão de Raios-X (XPS), das Curvas de Polarização, da Espectroscopia de Impedância Eletroquímica (EIE), da Microscopia Eletrônica de Varredura (MEV) e Espectrometria de Energia Dispersiva (EDS). Os resultados de EIE e polarização indicaram que os sistemas estudados foram eficientes contra corrosão e que seu desempenho dependia do tipo de silano. Os sistemas ZnFe+Ce+BTSE+BTESPTS e ZnFe+La+BTSE+BTESPTS mostraram o melhor resultado contra corrosão.
Abstract: Galvanized and zinc electroplated steels are very useful materials in automotive and construction industries. These zinc based materials, however, need to be protected against corrosive environments through a surface treatment that generally has hexavalent chromium wich is toxic to the environment and may cause cancer to human being. This thesis shows a study about films containing different silanes: vinyltriethoxysilane (VS), bis-(1,2-[triethoxysilyl]ethane) (BTSE) or is-(3-[triethoxysilyl]-propyl]tetrasulfide (BTESPTS) and rare earth nitrates (Ce, La) as conversion coatings to the zinc-iron alloy electroplated steel. These systems were evaluated using X-Ray Photoelectron Spectroscopy (XPS), Polarization Curves, Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscopy (SEM) and EDS. The EIS and Polarization results have shown that the systems under study were efficient against corrosion and its performance depended upon the type of silane. The inciron+Ce+BTSE+ BTESPT and zinc-iron+La+BTSE+BTESPT systems have shown the best result against corrosion.
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Cordes, Martin. « Intramolekulare Cyclisierungen chiraler, "c-zentrierter" Propargylsilane und enantioselektive Synthesen anellierter Azeptine zum Aufabu des BD-Grundgerüstes von Cephalotaxin ». [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975446096.
Texte intégral
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Ehbets, Julia [Verfasser], et R. [Gutachter] Tacke. « (β-AMINOALKYL)Silane : Synthese und Hydrolyseuntersuchungen von Cα-, Cβ-, Cγ- UND Cζ-funktionalisierten Alkoxy(Aminoalkyl)Silanen / Julia Ehbets. Gutachter : R. Tacke ». Würzburg : Universität Würzburg, 2016. http://d-nb.info/1111785856/34.
Texte intégral
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Zoran, Radovanović. « Uticaj ozimih međuuseva na dinamiku mineralnog azota, prinos i kvalitet silažnog kukuruza ». Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=105509&source=NDLTD&language=en.
Texte intégralRésumé :
Savremena poljoprivredana proizvodnja mora da odgovori na sve veće zahteve u pogledu zaštite životne sredine, smanjenja troškova proizvodnje i rasta tražnje za visoko kvalitetnim i zdravstveno bezbednim proizvodima. U takvim uslovima, jedan od odgovora poljoprivrednih proizvođača na postavljene izazove je i gajenje ozimih međuuseva jer oni mogu pružiti različite ekološke i proizvodne prednosti u poljoprivrednoj proizvodnji. Zbog toga, cilj rada je ispitati koje biljne vrste se mogu gajiti kao ozimi međuusevi u našim agroekološkim uslovima, kakav je njihov uticaj na zemljište, kakve su prednosti njihove primene za stočnu hranu ili za zelenišno đubrenje i kakav im je uticaj na sledeći usev. Ogled je postavljen na tri lokaliteta po metodi slučajnog blok sistema u tri ponavljanja. Istraživanja su izvršena u dva proizvodna ciklusa, od oktobra 2011. godine, kada su posejani ozimi međuusevi, do septembra 2013. kada je pokošen kukuruz za silažu. Biljne vrste korišćene za ozime međuuseve su maljava grahorica (Vicia vilosa Roth., sorta NS-Sirmium), ozimi tritikale (x Triticosecale Wittm. ex A. Camus, sorta Odisej) i njihova smeša. Pored varijanti sa ozimim međuusevima u ogled su uključene i varijante sa đubrenjem mineralnim azotom prema N-min metodi do 120 kg/ha azota (N1) i do 160 kg/ha azota (N2), kao i kontrola. Ozimi međuusevi posejani u prvom bloku su korišćeni za krmu, dok su međuusevi posejani u drugom bloku zaorani. U zavisnosti od vremenskih uslova ispitivane biljne vrste i njihove smeše gajene kao ozimi međuusevi, mogu da ostvare visoke prinose. Njihovim zaoravanjem značajno se može popraviti sadržaj mineralnog azota u zemljištu i obezbediti značajno povećanje proizvodnje kabaste stočne hrane na gazdinstvima. Dinamika mineralnog azota u zemljištu visoko je zavisna od ozimih međuuseva i najniži sadržaj azota je posle njihove žetve. Od ispitivanih vrsta, najvišu količinu azota iznosi tritikale, zatim ozima krmna smeša, a najmanje ozima grahorica. Od setve do žetve silažnog kukuruza, sadržaj mineralnog azota u zemljištu se povećava na svim tretmanima. Sadržaj mineralnog azota na kraju vegetacije je viši na tretmanima gde je zelena masa međuuseva odneta sa parcele. Međutim, preostalakoličina azota (ARNS) posle žetve kukuruza statistički je značajno viša na tretmanima gde su zaorani ozimi međuusevi od tretmana gde su oni odneti sa parcele i kreće se u intervalu od 66 do 150 kg N ha-1, a najveća je posle ozime krmne smeše. Prinosi zelene mase kukuruza u naknadnoj setvi posle ozimih međuuseva niži su u odnosu na varijante sa đubrenjem i kontrolu i kreću se od 6,6 t ha-1 do 22 t ha-1, dok kvalitet silokrme zadovoljava energetski potencijal kao i sadržaj proteina i minerala za kvalitetnu ishranu stoke na gazdinstvima. DatumA modern agricultural production must respond to increasing demands in terms of environmental protection, reduction of production costs and an increased demand for high quality, safe and healthy products. In such conditions, one of the responses of agricultural producers to the challenges posed is also cultivation of winter cover crops, because they can provide different advantages in agricultural production in terms of ecology and production. Therefore, the aim of the research is to examine which plant species can be cultivated as winter cover crops in our agroecological conditions, their impact on the soil, the benefits of their application as animal feed or green fertilizer, and the impact they have on the subsequent crop. The field experiment was conducted on three locations using the random block design with replications. The research was carried out in two production cycles, from October 2011, when the winter cover crops were sown, to September 2013, when corn was reaped for silage. Herbaceous species used for winter cover crops are hairy vetch (Vicia vilosa Roth., variety NS-Sirmium), winter triticale (x Triticosecale Wittm. Ex A. Camus, Odyssey variety) and their mixture. In addition to variants with winter cover crops, variants with fertilization with mineral nitrogen according to the N-min method up to 120 kg/ha of nitrogen (N1) and up to 160 kg/ha of nitrogen (N2), as well as a control, are included in the field experiment. Winter cover crops sown in the first block were used for fodder, while the winter cover crops sown in the second block were ploughed. Depending on weather conditions of the tested plant species and their mixture grown as winter cover crops, they can achieve high yields. Their ploughing can significantly improve the content of mineral nitrogen in soil and provide a significant increase in voluminous fodder production in farms. The dynamics of mineral nitrogen in soil is highly dependent on winter cover crops and the nitrogen content is the lowest after their harvest. Out of the tested species, the highest nitrogen uptake was by triticale, then winter forage mix and the smallest by winter vetch. In the period from sowing to harvest of silage corn, thecontent of mineral nitrogen in soil increases with all treatments. The content of mineral nitrogen at the end of the vegetation is higher with treatments where the green mass of the cover crops were taken away from the plot. However, the remaining quantity of nitrogen (ARNS) after corn harvest was, statistically speaking, significantly higher in treatments where winter cover crops were ploughed, from the treatment where they were taken away from the plot and ranges from 66 to 150 kg N ha-1; the largest nitrogen content was measured after winter forage mix. The green mass yields of corn in subsequent sowing after winter cover crops are lower compared to fertilized variants and the control and range from 6.6 t ha-1 to 22 t ha-1, while the quality of silage meets the energy potential, as well as the content of proteins and minerals for quality livestock feed on farms.
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Gang, Andreas. « Towards bottom-up silicon nanowire-based biosensing : ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235724.
Texte intégralRésumé :
The term "Lab-on-a-Chip" (LoC) describes highly miniaturized systems in which the functionalities of entire laboratories are scaled down to the size of transportable microchips. Particularly in the field of chemical and bio-analysis, such platforms are desired for a fast and highly sensitive sample analysis at the point of care. This work focuses on silicon nanowire (SiNW) based sensors. Innovative device fabrication concepts are developed from various directions, for a facile and reliable assembly of LoC analysis systems. Firstly, a multifunctional microfluidic set-up is developed which allows for a facile reversible sealing of channel structures on virtually any kind of substrate while maintaining the possibility of a rapid prototyping of versatile channel designs and the applicability of high working pressures of up to 600 kPa. Secondly, a 3-(triethoxysilyl)propylsuccinic anhydride (TESPSA) based surface modification strategy for the attachment of specific receptor molecules without additional binding site passivation is explored. Thirdly, bottom-up grown SiNWs are utilized for producing parallel arrays of Schottky barrier field-effect transistors (FETs) via contact printing. Using the initially developed microfluidic set-up, the concept of the TESPSA-based receptor immobilization is proved via fluorescence microscopy and by applying the SiNW FETs as biosensors. Using a receptor-analyte system based on a set of antibodies and a peptide from human influenza hemagglutinin, it is shown that antibodies immobilized with the developed method maintain the specificity for their antigens. The fourth major research field in this work is the microfluidics-based alignment of one-dimensional nanostructures and their deposition at predetermined trapping sites for reliably fabricating single NW-based FETs. Such devices are expected to provide superior sensitivity over sensors based on parallel arrays of FETs. Consequently, within this work, innovative LoC devices fabrication approaches over a broad range of length scales, from micrometer scale down to the molecular level, are investigated. The presented methods are considered a highly versatile and beneficial tool set not only for SiNW-based biosensors, but also for any other LoC applicationUnter dem Begriff „Lab-on-a-Chip“ (LoC) fasst man stark miniaturisierte Systeme zusammen, die die Fähigkeiten eines ganzen Labors auf einen transportablem Mikrochip übertragen. Insbesondere im Bereich der Analyse chemischer und biologischer Proben werden solche Plattformen bevorzugt eingesetzt, da sie direkt am Ort der Probenentnahme schnelle, hoch sensible Messungen ermöglichen. Im Mittelpunkt dieser Doktorarbeit stehen Sensoren auf Basis von Siliziumnanodrähten (SiNWs). Auf verschiedenen Gebieten werden innovative Konzepte zur einfachen und zuverlässigen Herstellung von LoC Systemen entwickelt. Zu Beginn wird ein multifunktionaler Mikrofluidik-Aufbau vorgestellt, der ein einfaches reversibles Verschließen von Mikrofluidik-Kanälen auf nahezu allen möglichen Substraten erlaubt. Der Aufbau ermöglicht das schnelle Anfertigen und Testen verschiedener Kanalstrukturen sowie das Betreiben von Fluidik-Experimenten mit hohen Arbeitsdrücken von bis zu 600 kPa. Der zweite Schwerpunkt der Arbeit ist die Entwicklung einer Methode zur Funktionalisierung von Sensor-Oberflächen mittels 3-(Triethoxysilyl) Propyl Bernsteinsäure Anhydrid (TESPSA) für die Immobilisierung spezifischer Rezeptormoleküle. Bei dieser Methode entfällt die Notwendigkeit einer zusätzlichen Passivierung ungenutzter Anbindungsstellen. Des Weiteren erfolgt die Herstellung von Parallelschaltungen von Schottky-Barrieren-Feld-Effekt-Transistoren (SB-FETs) aus „bottom-up“ gewachsenen SiNWs durch mechanisches Abreiben der SiNWs vom Wachstumssubstrat auf ein Empfängersubstrat. Unter Verwendung des eingangs entwickelten Mikrofluidik-Aufbaus wird die prinzipielle Anwendbarkeit der TESPSA-basierten Rezeptor-Immobilisierung nachgewiesen, sowohl anhand von Fluoreszenzmikroskopie-Untersuchungen als auch mit Hilfe der SiNW FETs als Biosensoren. Mittels eines Rezeptor-Analyt-Systems, bestehend aus verschiedenen Antikörpern und einem Peptid des Influenzavirus A, wird gezeigt, dass Antikörper, die über TESPSA an Oberflächen gebunden werden, ihre Spezifizität für ihre Antigene beibehalten. Der vierte große Forschungsabschnitt dieser Arbeit widmet sich der mikrofluidischen Ausrichtung eindimensionaler Nanomaterialien und deren Ablage an vorgegebenen Fangstellen, wodurch eine zuverlässige Herstellung von FETs aus Einzelnanodrähten erreicht wird. Es wird davon ausgegangen, dass Einzelnanodraht-FETs gegenüber Parallelschaltungen von Nanodraht-FETs verbesserte Sensoreigenschaften aufweisen. Folglich beinhaltet diese Arbeit viele zukunftsweisende Ansätze für die Herstellung von LoC Systemen. Untersuchungen über eine Bandbreite von Längenskalen, von Mikrometer großen Strukturen bis hinab zur molekularen Ebene, werden präsentiert. Es wird davon ausgegangen, dass die vorgestellten Methoden als eine vielfältige Sammlung von Werkzeugen nicht nur bei der Herstellung von Biosensoren auf SiNW-Basis Einsatz finden, sondern ganz allgemein den Aufbau verschiedenster LoC Systeme vorantreiben
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Cuevas-Chávez, Cynthia. « Synthèse, structure et réactivité de complexes de platine et d'iridium à ligands phosphinodi(benzylsilanes) ». Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30196.
Texte intégralRésumé :
Une chimie riche et des possibilités d'applications dans un large éventail de domaines (par exemple, l'activation de petites molécules, les transformations sélectives, y compris les développements catalytiques, etc.) des composés de type pince à base de silicium avec des métaux de transition ont été attestés par des progrès remarquables en chimie de coordination ainsi qu'en organométallique. Cela est dû aux propriétés remarquables des atomes de Si qui génèrent des centres métalliques riches en électrons labellisant de manière concomitante les substituants trans. Cependant, malgré la pléthore d'arrangements de telles espèces dans la littérature (par exemple, le cadre, le nombre et la nature des points d'ancrage), les dérivés métalliques à ligands polydentates incorporant deux atomes de silicium sont limités, de même que l'étude de leur réactivité. Par conséquent, cette thèse présente la synthèse, la structure et la réactivité de nouveaux complexes de platine et d'iridium supportés par le ligand de type pince "SiPSi". Il est intéressant de noter que le complexe PtII carré-plan de formule trans-[(SiPSi)Pt(PPh3)] (SiPSi = P(o C6H4CH2SiMe2)2Ph) réagit de manière réversible avec de petites molécules, H2 et CO, formant le dihydrure et le dicarbonyle correspondants, espèces à 18 d'électrons, respectivement. D'autre part, le complexe dimérique [Ir(SiPSi)(µ-Cl)]2 se dissocie dans une solution benzénique pour donner l'espèce monomère à 14-électrons [Ir(SiPSi)Cl] qui réagit facilement avec des donneurs à deux électrons. Les configurations à 16- et 18-électrons sont obtenues en fonction principalement de l'encombrement stérique dans le cas des dérivés P. Différentes dispositions de ligands L sur des espèces de 18-électrons (L = CNCD3, CO) et le processus d'isomérisation ont également été mis en évidence. De plus, même si l'iridium a tendance à effectuer des additions oxydatives, nous avons également montré que la liaison agostique Si-H peut favoriser l'activation par C-H d'un groupe méthylène acide adjacent menant à un ligand tétradentateThe rich chemistry and applicability in such a wide range of fields (e.g. small molecule activation, selective transformations including catalytic developments, etc.) of silicon based pincer-like compounds with transition metals has been witnessed by the remarkable advances in coordination chemistry as well as in organometallics. This is due to the outstanding properties of Si atoms which generate electron rich metal centres concomitantly labilizing trans substituents. However, despite all the plethora of arrangements of such species throughout the literature (e.g. framework, number and nature of anchoring points), metal derivatives with polydentate ligands incorporating two silicon atoms are limited as is the study of their reactivity. Therefore, this thesis presents the synthesis, structure and reactivity of novel Platinum and Iridium complexes supported by the "SiPSi" pincer-type ligand. Interestingly, the square-planar PtII complex of formula trans-[(SiPSi)Pt(PPh3)] (SiPSi = P(o-C6H4CH2SiMe2)2Ph) reversibly reacts with small molecules, H2 and CO, forming the corresponding dihydride and dicarbonyl 18-electron species, respectively. On the other hand, the dimeric complex [Ir(SiPSi)(µ-Cl)]2 dissociates in benzene solution to yield the 14-electron monomeric species [Ir(SiPSi)Cl] which readily reacts with two electron donors. 16- and 18-electron configurations are obtained depending mainly on sterics in the case of P-derivatives. Different dispositions of L ligands on 18-electron species (L = CNCD3, CO) and isomerisation processes were also evidenced. Moreover, even if iridium is prone to perform oxidative additions, we also showed that Si-H agostic bonding can favour C-H activation of an adjacent acidic methylene group leading to a tetradentate ligation
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Römhildt, Lotta. « Biochemical functionalization of silicon dioxide surfaces for sensing applications ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-148666.
Texte intégralRésumé :
The aim of this work was to functionalize silicon dioxide surfaces with biochemical molecules in such a way that biorecognition of target molecules in solution will be possible. By introducing a tool set of different molecules and characterization methods, a more universal approach towards various biosensor setups is presented. This includes on the one hand preparation of the biosensor surfaces to allow further molecule attachment via their reactive functional groups. Secondly, the selection of chemical molecules providing suitable counterparts for abundant functional groups of potential receptors is discussed. Two detection schemes are introduced – based on an antibody to detect the antibiotic amoxicillin and aptamers to detect thrombin. The antibody was implemented in an inverse competition assay to probe such small target molecules. Antibiotic residues are often present in wastewater. Aptamers, so-called artificial antibodies, were selected as they provide many advantages over antibodies. As a model system, two different thrombin binding aptamers were chosen which allowed to perform sandwich assays as well. The protein thrombin plays an important role in the blood coagulation cascade. To probe the individual modification steps, different techniques for analysis were applied. Surface micropatterning was introduced to improve recognition of modified areas and fluorescence-to-background ratios resulting in a thrombin detection limit down to 20 pM. One important goal was the integration in ion-sensitive field-effect transistor devices. Aptamers are small in size which might enable a higher sensitivity of these devices compared to the use of antibodies because of the Debye layer thickness. As a final step, first measurements towards silicon nanowire based field-effect transistor biosensors were carried out on devices with bottom-up and top-down fabricated nanowires using both proposed receptor-analyte combinations. The potential of these devices as portable sensors for real-time and label-free biosensing is demonstratedZiel dieser Arbeit war es Siliziumdioxidoberflächen so mit biochemischen Molekülen zu funktional- isieren, dass die biologisch spezifische Erkennung von Zielmolekülen in Lösung möglich wird. Hier wird eine Auswahl an geeigneten Molekülen und Charakterisierungsmethoden für einen vielseitigen Ansatz gezeigt, der auf verschiedene Biosensorsysteme anwendbar ist. Das beinhaltet zum Einen die Präparation der Biosensoroberflächen, so dass die Moleküle über reaktive funktionelle Gruppen angebunden werden können. Als zweites ist die Auswahl der chemischen Moleküle wichtig, da diese die passenden Gegenstücke zu potentiellen funktionellen Gruppen der Rezeptoren darstellen. Zwei verschiedene Detektionsvarianten werden eingeführt – Antikörper gegen das Antibiotikum Amoxicillin und Aptamere gegen Thrombin. Der Antikörper wurde in einen inversen Wettbewerbsassay integriert um einen solch kleinen Ana- lyten detektieren zu können. Rückstände von Antibiotika sind häufig in Abwässern zu finden. Ap- tamere, sogenannte künstliche Antikörper, weisen gegenüber Antikörpern viele Vorteile auf. Als ein Modellsystem wurden zwei unterschiedliche Thrombin bindende Aptamere verwendet, was auch die Durchführung von Sandwich Assays ermöglichte. Das Protein Thrombin spielt eine wichtige Rolle bei der Blutgerinnung. Um die einzelnen Modifikationsschritte zu untersuchen, wurden verschiedene Charakterisierungsmethoden angewendet. Die Mikrostrukturierung der Funktionalisierung erleichterte die Erkennung der modifizierten Flächen und verbesserte das Fluoreszenz-zu-Hintergrund Verhältnis. Das führte zu einer Detektionsgrenze von 20 pM für Thrombin. Ein wichtiges Ziel dieser Arbeit war die Integration der Funktionalisierung in einen ionen-sensitiven Feldeffekttransistor. Die kleinen Aptamere könnten dabei aufgrund der geringen Debye-Schichtdicke bei diesen Sensoren eine höhere Sensitivität als mit Antikörpern ermöglichen. Zuletzt wurden erste Messungen hin zu Silizium Nanodraht basierten Feldeffekttransistor Biosen- soren mit beiden untersuchten Rezeptor-Analyt-Kombinationen durchgeführt. Sowohl die Chips mit bottom-up als auch mit top-down gewachsenen Nanodrähten zeigen dabei ihr Potential als handliche Sensoren zur markerfreien Detektion in Echtzeit
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Rugeri, Baptiste. « Hémisynthèse stéréosélective d’acides aminés hétérosubstitués sur la chaîne latérale : application au radiofluoromarquage pour l’imagerie de peptides ». Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK060/document.
Texte intégralRésumé :
Hemisynthèse stéréosélective d’acides aminés hétérosubstitués sur la chaîne latérale.Applications au radio-fluoromarquage pour l’imagerie de peptides.Ce travail de thèse, qui a été réalisé à l’Institut de Chimie Moléculaire de l’Université de Bourgogne et en collaboration avec l’Institut de Neuroscience Cognitives et Intégrative d’Aquitaine, porte sur la mise au point de nouvelles méthodes de synthèse d’acides aminés hétérosubstitués sur la chaine latérale par des groupements phosphorés ou silylés, ainsi que sur leurs applications. Dans une première partie, la synthèse d’acides aminés silylés sur la chaine latérale est réalisée sans racémisation par réaction de Wittig entre un sel de phosphonium, dérivé d’acide L-aspartique, avec un aldéhyde aromatique porteur du groupement silylé. Ces acides aminés ont été utilisés en synthèse peptidique pour donner des di- et tripeptides silylés par réaction avec des dérivés d’alanine et de phénylalanine. Il a été montré que les acides aminés et peptides silylés pouvaient être fluorés par réaction avec des fluorures, et que dans le cas de dérivés di-t-butylsilylés, les composés fluorés obtenus se révèlent d’une très grande stabilité à pH physiologique. L’étude de la fluoration des peptides di-t-butylsilylés par K18F/K222 a permis d’obtenir les dérivés radiomarqués avec des rendements radiochimiques et des activités molaires atteignant respectivement 39% et 410 GBq.mmol-1. Dans la seconde partie, la synthèse d’acides aminés et peptides hétérosubstitués ou fonctionnalisés sur la chaine latérale, a été mise au point. Le principe de cette synthèse repose sur une cycloaddition [3+2] entre un acide aminé porteur d’un groupement azido avec un alcyne disubstitué. Alors que la réaction par catalyse avec un sel de cuivre ou un complexe de ruthénium ne conduit pas aux produits recherchés, la cycloaddition a été mise au point sous microondes en utilisant le glycérol comme solvant. Dans ces conditions, 13 nouveaux acides aminés porteurs d’un noyau triazole en position γ, et des substituants silylés, phosphorés, amines, amides …ont été préparés sans racémisation et ce avec des rendements atteignant 89%. Les méthodologies mises au point dans ce travail de thèse offrent de nouvelles voies pour la synthèse de dérivés acides aminés silylés ou phosphorés utiles pour la chimie de coordination, la catalyse asymétrique et pour le radiomarquage par les ions fluorure 18F-.Mots clés : Phosphoniums, acides aminés, silanes ; [18F]-radiofluoration, triazolesStereoselective hemisynthesis of lateral chain heterosubstituted aminoacids.Applications on radiofluorolabeling for peptide imaging.This thesis work, which was carried out at the Institute of Molecular Chemistry of the University of Burgundy and in collaboration with the Institute of Cognitive and Integrative Neurosciences of Aquitaine, focuses on the development of new methods for the synthesis of side chain heterosubstituted amino acids including phosphine containing or silyl groups, as well as on their applications. In a first part, the synthesis of side chain silylated amino acids is achieved without racemization using a key Wittig reaction between a phosphonium salt, derived from L-aspartic acid, and an aromatic aldehyde bearing the silyl group. These aminoacids have been used in peptide synthesis to give silylated di- and tripeptides by reaction with alanine and phenylalanine derivatives. It has been shown that the silylated aminoacids and peptides can be fluorinated by reaction with fluorides, and that in the case of di-t-butylsilyl derivatives, the fluorinated compounds obtained are found to be very stable at physiological pH. The study of the fluorination of di-t-butylsilyl peptides by K18F / K222 allowed to obtain radiolabelled derivatives with radiochemical yields and molar activities reaching 39% and 410 GBq.mol-1, respectively. In the second part, the synthesis of aminoacids and peptides heterosubstituted or functionalized on the side chain, was developed. The principle of this synthesis is based on a [3 + 2] cycloaddition between an aminoacid bearing an azido group with disubstituted alkyne. While the reaction catalyzed using a copper salt or a ruthenium complex does not lead to the desired products, the cycloaddition was developed under microwave irradiation using glycerol as a solvent. Under these conditions, 13 new amino acids carrying a triazole ring at the γ position, and bearing silyles, phosphines, amines, amides.. substituents were prepared without racemization and with yields up to 89%. The methodologies developed in this thesis offer new efficient ways for the synthesis of silyl or phosphorus amino acid derivatives, useful for coordination chemistry, asymmetric catalysis and radiolabeling by the fluoride ion18F-.Key words: Phosphoniums, aminoacids, silanes, [18F]-radiofluorination, triazoles
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Peixoto, Leticia Monteiro. « Efeito da temperatura de secagem de dois tipos de silano e da supressão ou redução do tempo de condicionamento com ácido hidrofluorídrico na resistência de união entre uma cerâmica de dissilicato de lítio e um cimento resinoso ». Universidade do Estado do Rio de Janeiro, 2012. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=6346.
Texte intégralRésumé :
Conselho Nacional de Desenvolvimento Científico e TecnológicoEste estudo avaliou o efeito de diferentes métodos de silanização e aplicação do ácido hidrofluorídrico (HF) sobre a resistência à microtração de uma cerâmica de dissilicato de lítio a um cimento resinoso. Quarenta blocos de IPS e.max Press /Ivoclar Vivadent (5x5x6mm) foram cimentados a blocos de resina Z250/3M ESPE (5x5x6mm) usando o cimento resinoso RelyX ARC/3M ESPE de acordo com os seguintes métodos de tratamento superficial: G1: 20s de ácido fluorídrico (HF) + silano não hidrolisado Primer-Activactor/Dentsply (SNH) seco à temperatura ambiente; G2: 20s HF + silano pré-hidrolisado RelyX Ceramic-Primer/3M ESPE (SPH) seco à temperatura ambiente; G3: 10s HF + SNH seco com ar quente (50oC-2min); G4: 10sHF + SPH seco com ar quente (50oC-2min); G5: sem ácido, SNH seco com ar quente (50oC-2min); G6: sem ácido, SPH seco com ar quente (50oC-2min); G7: sem ácido, SNH seco à temperatura ambiente; G8: sem ácido, SPH seco à temperatura ambiente. Antes de cada método de silanização, os blocos cerâmicos receberam acabamento com lixas de carbeto de silício (220-600) e limpeza com ácido fosfórico 37% (1min). A cimentação foi realizada com carga vertical de 1kg por 10min. Os conjuntos de cerâmica/cimento/resina foram armazenados em água destilada (37C) por 24 horas e depois seccionados em máquina de corte Isomet 1000 a fim de obter palitos (n = 40) de 1mm2 de área da seção transversal, que foram submetidos ao teste de microtração em máquina de ensaio universal Emic (v = 0,5mm/min). O modo de fratura foi avaliado em microscópio eletrônico de varredura. A análise estatística foi realizada utilizando ANOVA / Dunnett (p-valor = 0,000). As médias MPa e desvio padrão foram: G1-21,5 (8,9) BC; G2-30,5 (7,2) A; G3-19.4 (9.1) BC; G4-24,0 (9,0) B; G5-8.1 (3.2) D; G6 -18,0 (6,2) C; G7-7.8 (2,6) D; G8-6.3 (2,5) D. Grupos 2, 3, 4 e 6 não tiveram falhas prematuras dos palitos contra os grupos 1, 5, 7 e 8, que apresentaram 2,2; 44,4; 75,6 e 33,3% de perdas prematuras, respectivamente. O teste de correlação foi realizado apresentando significância estatística, com valor de -0,736 (p-valor = 0,000), mostrando que, a medida que o percentual de perda prematura aumenta, a média da MPa diminui. Quanto ao modo de fratura, observou-se 44,97% de falhas do tipo mista, 51,70% de falhas do tipo adesiva, 3,33% de falhas do tipo coesiva do cimento. Quando é realizada a supressão do condicionamento com HF como pré-tratamento da superfície cerâmica IPS e.max Press, a aplicação de silano SPH, associada ao seu tratamento térmico, deve ser o método de silanização recomendado, embora os valores mais elevados de resistência de união tenham sido os obtidos quando utilizado o condicionamento com HF por 20s. Quando é realizada a redução do tempo de condicionamento com HF para 10s, a aplicação do silano (SPH ou SNH) deve ser sempre associada ao seu tratamento térmico. O SNH só deve ser usado se as superfícies das cerâmicas IPS e.max Press forem tratadas com HF.
This study devaluated the effect of different types of silanization and hydrofluoric acid on the microtensile bond strength of a lithium dissilicate ceramic system. Forty IPS e.max Press /Ivoclar Vivadent blocks (5x5x6mm) were cemented to Z250/3M ESPE resin blocks (5x5x6mm) using RelyX ARC/3M ESPE resin-cement according to the following silanization methods: G1: 20s hydrofluoric acid (HF) + non-hydrolyzed silane Primer-Activactor/Dentsply (NHS) dried at room temperature; G2: 20sHF + pre-hydrolyzed silane RelyX Ceramic-Primer/3M ESPE (PHS) dried at room temperature; G3: 10sHF + NHS dried with hot air (50oC-2min); G4: 10sHF + PHS + hot air; G5: NHS + hot air; G6: PHS + hot air; G7: NHS dried at room temperature; G8: PHS dried at room temperature. Before each silanization method, all ceramic blocks were abraded with SiC grit papers (220-600) and cleaned with 37% phosphoric acid (1min). The cementation was made with vertical load of 01 kg for 10 min. After cementation procedure, all ceramic/ciment/resin blocks were stored in distilled water (37oC) for 24h before being cut to obtain stick-shapped specimens (n=45) of approximately 1mm2 cross-sectional area for microtensile test (v=0.5mm/min). Statistical analysis was performed using ANOVA/Dunnett (p-value = 0,000). The mean MPa(SD) values were: G1-21.5(8.9)BC; G2-30.5(7.2)A; G3-19.4(9.1)BC; G4-24.0(9.0)B; G5-8.1(3.2)D; G6-18.0(6.2)C; G7-7.8(2.6)D; G8-6.3(2.5)D. Groups 2, 3, 4 and 6 had no sticks premature fail against groups 1, 5, 7 and 8, that had 2.2, 44.4, 75.6 and 33.3% of sticks premature fails, respectively. As the correlation coefficient was statistically significant, -0.736 (p-value = 0.000), it could be argued that as the percentage of premature loss increased the MPa mean decreases. The failure mode was 44.97% of mixed failures, 51.70% of adhesive failures, 3.33% of cohesive failures of the cement. When the pretreatment is performed without HF conditioning of the IPS e.max Press ceramic surface, then PHS with hot air application should be the silanization method recommended, although higher bond strength values were obtained when HF conditioning for 20s was used with this type of silane. When the time of HF conditioning is reduced for 10 sec, the application of silane (SPH or SNH) must be always related to its heat treatment. NHS should only be used if IPS e.max Press ceramic surfaces are treated with HF.
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Bengtsson, Magnus. « Silane Crosslinked Wood-Thermoplastic Composites ». Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-680.
Texte intégralRésumé :
Wood-thermoplastic composites are a more environmental friendly alternative for pressure-treated lumber but can also replace engineering plastic products. These composites have been on the market for more than ten years now and have mainly been used in building and automotive applications. The use of these materials has shown that long-term properties, durability, and toughness are the main problems. The aim of this study was to investigate if silane crosslinking could be one way of solving these problems. Silane crosslinked woodthermoplastic composites with polyethylene as the matrix and wood flour as reinforcement were manufactured by melt compounding. A reactive extrusion process was developed where compounding of polyethylene and wood flour and silane grafting were carried out simultaneously. The extrusion process was optimized and used in larger scale profiling of crosslinked composites. The composite materials were evaluated using chemical analysis, mechanical testing, spectroscopic analysis, thermal analysis, and electron microscopy. The crosslinking reaction was shown to be initiated during compounding of the composites and was significantly increased upon storage in a high humidity sauna at elevated temperature. The crosslinked composites showed toughness, impact strength and creep properties superior to the non-crosslinked composites. Scanning electron microscopy on the fracture surface of the crosslinked composites revealed good interfacial adhesion between the wood fibres and the polyethylene matrix. Based on results from this study, it is proposed that silane crosslinking creates a three dimensional network in the polyethylene matrix with chemical bonding to the wood fibres.
Future evaluation of results from accelerated weathering studies will reveal if silane crosslinking can improve the durability of wood-thermoplastic composites during outdoor exposure. Investigation of the potential of silane crosslinking on other type of composite systems with other thermoplastic matrices and natural fibres would also be of interest.
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Mohammed, Tan I. « Properties of silane-crosslinked HDPE ». Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234047.
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Tidrick, Shari Lynne. « Investigations of the silane/epoxy matrix interphase for silane coupling agent blends of varying composition ». Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055857671.
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Souza, Dayvson José Palmeira de. « Avanços e desafios na biocatálise dos compostos orgânicos de silício ». Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-21012015-082518/.
Texte intégralRésumé :
Aliando reações enzimáticas a compostos orgânicos de silício, objetivou-se explorar o potencial destes substratos em reações biocatalisadas. A intenção era ampliar o escopo de substratos e desbravar novas transformações. Inicialmente foram abordados os trabalhos relativos ao uso de hidrolases em reações envolvendo organossilanos, cujo uso de lipases foi o foco da nossa contribuição. Nela, a resolução cinética enzimática (RCE) de alcoóis quirais benzílicos contendo silício e outros heteroátomos (fósforo e estanho) foi explorada e transesterificações enantiosseletivas eficientes foram alcançadas, em que tanto os produtos acetilados e os alcoóis remanescentes foram obtidos em excelentes excessos enantioméricos (e.e. >99% em todos os casos). Considerações sobre a relação estrutura/atividade das reações catalisadas por lipase foram feitas, e foi possível perceber que os compostos contendo silício reagiram mais rapidamente que aqueles contedo fósforo e estanho. Em seguida, numa extensão natural da RCE, buscou-se realizar a resolução cinética dinâmica (RCD). Diversos experimentos de RCD foram realizados utilizando lipase e dois tipos de catalisadores de racemização diferentes: complexos de rutênio e uma resina de troca catiônica. Embora tenham sido encontrados indícios de que a racemização utilizando os catalisadores de rutênio estava acontecendo no meio reacional, a inativação do catalisador durante o processo foi uma dificuldade que, nos estudos realizados, não foi possível contornar. Foi então que uma resina de troca catiônica foi utilizada como alternativa de racemização, e dependendo do substrato utilizado foi possível realizar eficientes RCDs (rendimento até 93% e e.e. até 96%) através de uma esterificação enzimática empregando um acilante de cadeia longa. O último trabalho empregando hidrolases foi na acilação de silanóis. A partir dos resultados interessantes envolvendo a acilação de um silanol arílico (conversão de 75% para o acetoxissilano derivado usando a CAL-B), tentou-se acilar um silanol benzílico racêmico e, embora o substrato tenha sido acetilado enzimaticamente (conversão de até 47% para o acetoxissilano derivado nas condições estudadas), a reação se deu sem enantiosseletividade. Nas reações envolvendo oxidorredutases, tanto mono-oxigenases quanto enzimas provenientes da bactéria Arthrobacter sp., foram empregadas como biocatalisadores. Na tentativa de se realizar a oxidação da ligação C-Si utilizando BVMOs (Baeyer-Villiger mono-oxigenases), foi possível concluir que a instabilidade dos silanos e alcoxissilanos nas reações em meio aquoso poderia configurar um entrave no desenvolvimento da metodologia. Por outro lado, evidências de oxidação enzimática da ligação Si-H foram observadas em dois substratos arílicos, que podem servir de direcionamento para futuros projetos envolvendo este tema. Por fim, células íntegras da bactéria Arthrobacter sp. foram utilizadas em reações de desracemização aeróbica (R)-seletiva de alcoóis e redução anaeróbica (S)-seletiva de cetonas, ambas utilizando substratos contendo silício, fósforo, estanho e boro. Transformações com elevada enantiosseletividade foram encontradas, provando a versatilidade da Arthrobacter sp. em mediar reações enantiocomplementares.By combining both enzymatic reactions and organosilicon compounds, we aimed to explore the potential of these substrates in biocatalytic reactions. The main goal was to expand the scope of substrates and breakthrough new transformations. Initially the study was based on the use of hydrolases in reactions involving organosilanes, in which lipases were the focus of our contribution. Thus, enzymatic kinetic resolution (EKR) of chiral benzylic alcohols containing silicon and other heteroatoms (phosphorus and tin) was explored and efficient enantioselective transesterifications were achieved, in which both acetylated products and remaining alcohols were obtained in excellent enantiomeric excesses (e.e. > 99% in all cases). Considerations about the structure/activity relationship of lipase-catalyzed reactions were done, and it was found out that silicon-containing compounds can react faster than those phosphorus- or tin-containing analogues. Then, an extension of EKR was the dynamic kinetic resolution (DKR). Several experiments were performed using lipase and different racemization catalysts: ruthenium complexes and a cation exchange resin. Although racemization by ruthenium catalysts have been found, in our studies inactivation of the catalyst during the process was a problem that was not possible to be solved. A cation exchange resin was used in racemization, and depending on the substrate it was possible to perform efficient DKRs (yield up to 93% and e.e. up to 96%) via an enzymatic esterification using an acylating agent with long chain. Another work with hydrolases was the enzymatic acylation of silanols. From the interesting results involving the acylation of an aryl-silanol (75% conversion to the acetoxy-silane derivative, by CAL-B), the acylation of a racemic benzyl-silanol was performed and although the substrate has been successfuly acetylated by a series of lipases (up to 47% conversion to the acetoxy-silane derivative under the conditions studied), the reaction occurred without any enantioselectivity. In reactions involving oxidoreductases, both mono-oxygenases and enzymes from the bacterium Arthrobacter sp., were used as biocatalysts. In an attempt to carry out the oxidation of the C-Si bond using BVMOs, it was found out that the instability of the substrates in aqueous media could set an obstacle in the development of the methodology. Moreover, evidence of enzymatic oxidation of Si-H bond were observed for two aryl substrates, which can serve as guidance for future projects involving the topic. Finally, whole cells of the bacterium Arthrobacter sp. were used for (R)- selective deracemization of alcohols and (S)-selective reduction of ketones, both using silicon-, phosphorus-, tin- and boron-containing substrates. Transformations with high enantioselectivity were achieved, showing the versatility of Arthrobacter sp. in mediating enantiocomplementary reactions.
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Bexell, Ulf. « Surface Characterisation Using ToF-SIMS, AES and XPS of Silane Films and Organic Coatings Deposited on Metal Substrates ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributr], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3438.
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Colares, Regina ClÃudia Ramos. « Estudo comparativo da resistÃncia de uniÃo entre resina composta e cerÃmica submetida a diferentes tratamentos de superfÃcie ». Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5262.
Texte intégralRésumé :
nÃo hÃO reparo intraoral de restauraÃÃes cerÃmicas constitui-se de um mÃtodo clinicamente efetivo para a resoluÃÃo de fraturas de porcelana, e seu sucesso clÃnico depende da qualidade e durabilidade de uniÃo entre a resina composta e a superfÃcie da cerÃmica. O presente estudo teve como objetivo avaliar a resistÃncia de uniÃo entre a cerÃmica reforÃada com dissilicato de lÃtio à resina composta quando submetida ao jateamento com Ãxido de alumÃnio 50 μm ou ao condicionamento com Ãcido fluorÃdrico a 9,5%, empregando-se dois protocolos de silanizaÃÃo: secagem à temperatura ambiente ou mediante o aquecimento. Um total de 20 blocos de cerÃmica medindo-se (7x7x5mm) foram aleatoriamente dividos em 4 grupos (n=5): G1- condicionamento da superfÃcie da porcelana com o Ãcido fluorÃdrico a 9,5% por 20 segundos com secagem do silano à temperatura ambiente; G2- tratamento realizado da mesma forma que G1 empregando-se a secagem do silano com um jato de ar aquecido a 45Â5˚C; G3- jateamento com partÃculas de Ãxido de alumÃnio de 50 μm por 5 segundos e secagem do silano com um jato de ar aquecido e G4- tratamento realizado da mesma forma que G3 empregando-se a secagem à temperatura ambiente. ApÃs a realizaÃÃo dos tratamentos, aplicou-se adesivo (Single Bond 2) e cinco camadas de 1,5 mm de resina composta (Filtek Z250), obtendo-se um bloco de 10 mm de altura. Os blocos cerÃmica/resina foram armazenados em Ãgua destilada a 37 C por 24 h. Em seguida, foram feitos cortes seriados perpendiculares entre si para a obtenÃÃo de espÃcimes em forma de palito com Ãrea da secÃÃo transversal de 1mm2 que foram imediatamente testados atravÃs de ensaio de microtraÃÃo à velocidade de 1 mm/min. Os dados foram analisados por ANOVA e teste de Student-Newman Keuls (p <0,05). As mÃdias (desvio-padrÃo) foram em MPa: G1 - 32,14 (7,98); G2 â 35 (7,77) e G3 â 18,36 (6,17). O Grupo 4 nÃo pode ser avaliado pois houve o desprendimento da resina composta durante o procedimento de obtenÃÃo dos espÃcimes. G1 e G2 apresentaram maiores valores de resistÃncia à traÃÃo em relaÃÃo ao G3 (p<0.05). NÃo houve diferenÃa estatÃstica significante entre os Grupos 1 e 2 (p> 0.05). Concluiu-se que o aquecimento do silano teve importante papel no tratamento de superfÃcie da cerÃmica jateada com Ãxido de alumÃnio.
The intraoral repair of ceramic restorations consisted of a clinically effective method for solving fracture of porcelain, and its success depends on quality and durability of the bond between the ceramic and the resin. The purpose of this study was to evaluate the bond strength between lithium disilicate-based ceramic and composite resin when subjected to airborne-particule abrasion with 50 μm aluminum oxide or hydrofluoric acid treatment using two silanization protocols: drying at room temperature or by heating. Twenty blocks (7Ã7Ã5mm) of lithium disilicate-based hot-pressed ceramic were fabricated and randomly divided into four groups (n = 5): G1- etched with 9.5% hydrofluoric acid for 20 seconds silanated surface were dried with room-temperature air; G2- treatment performed the same way as G1 employing the drying of the silane surface was 45Â 5˚C warm air; G3- airborne-particle abrasion with 50-μm aluminum oxide for 5 seconds and silanated surface was dried 45Â 5˚C warm air; G4-treatment performed in the same way that G3 employing drying of silane at room temperature. After an adhesive (Single Bond 2) was applied and before adding 5 mm layers of a composite resin (Filtek Z250), obtaining a block of 10 mm in height. Each blocks ceramic / resin were stored in 37˚C distilled-water for 24 h and cut into ceramic-composite beams with 1mm2 of cross-sectional area for immediately tested by microtensile bond strenght test at a speed of 1 mm / min. Data were analyzed by ANOVA and Student-Newman Keuls (p <0.05). The mean (standard deviation) in MPa were: G1 - 32.14 (7.98), G2 - 35 (7.77) and G3 - 18.36 (6.17). Group 4 can not be assessed because there was a detachment of the resin during the procedure for obtaining specimens. G1 and G2 presented greater tensile strenght than G3 (p<0.05). There was no statistically significant difference between the mean values for groups G1 and G2 (p> 0.05). It was concluded that silane drying by a stream of warm air had an important role in the surface treatment of ceramic with air abrasion.
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Hammaecher, Catherine. « Acylsilanes et Bis(acyl)silanes : nouvelles méthodologies de synthèse et nouvelles réactivités ». Reims, 2007. http://theses.univ-reims.fr/exl-doc/GED00000726.pdf.
Texte intégralRésumé :
Les acylsilanes sont les composés «acyl-métal» présentant la chimie la plus diversifiée. Cette thèse porte d'une part sur de nouvelles synthèses (méthodes et produits) d'acylsilanes, d'autre part sur l'étude de leur réactivité. Plus particulièrement, des allyl- et vinyl(acyl)silanes et des bis(acylsilanes) à silicium internes étaient ciblés. Une synthèse basée sur l'hydrolyse d'éthers d'énol ou d'ènethiol C-silylés s'est révélée peu performante pour des bis(acylsilanes), mais apporte une contribution originale à la panoplie des méthodes de synthèse d'acylsilanes. Deux méthodes ont été étudiées pour la synthèse d'allyl- et vinyl(acyl)silanes. Une séquence silylation/déthiocétalisation du 2-phényl-[1,3]-dithiane a permis de préparer les allyl- et vinyl(benzoyl)silanes, et la méthode à été étendue à d'autres allyl(acyl)silanes. Une séquence silylation/alkylation du 1-phénoxyméthyl-1H-benzotriazole a conduit efficacement aux allyl- et vinyl(acyl)silanes à longue chaîne alkyle. Les allyl- et vinyl(acyl)silanes se sont révélés peu réactifs en métathèse. Cependant la métathèse cyclisante appliquée aux dérivés bis(insaturés) du benzotriazole a donné des intermédiaires cycliques avec de très bons rendements. La métathèse croisée appliquée à un allylsilane dérivé du benzotriazole a permis d'obtenir, après hydrolyse, le bis(acylsilane) correspondant. Les allyl(diméthyl)(acyl)silanes présentent une réactivité photochimique inédite comparée à celle des acyl(trialkyl)silanes. Les allyl(acyl)silanes donnent, par réaction de Paternò-Büchi intramoléculaire totalement régiosélective, des 1-alkyl-2,2-diméthyl-6-oxa-2- sila-bicyclo[2. 2. 0]hexanes, un nouveau type de structure bicycliqueAcylsilanes are «acyl-metal» compounds having the most varied chemistry. This PhD concerns, on the one hand, new synthesis (methods and products) of acylsilanes, on the other hand the study of their reactivity. A method of synthesis based on the hydrolysis of C-silyl enol or enethiol ethers proved to be inappropriate for the preparation of bis(acylsilanes), but provided an original contribution to the array of the acylsilanes synthetic methods. The synthesis of allyl- and vinyl(acyl)silanes and allyl- and vinyl(aroyl)silanes was performed from two types of precusors. Allyl- and vinyl(benzoyl)silanes were prepared by a sequence of silylation/dithioketalisation of 2-phenyl-[1,3]-dithiane and the methodology was extended to aliphatic allyl(acyl)silanes. A sequence silylation/alkylation applied to 1-phenoxyméthyl-1Hbenzotriazole led to allyl- and vinyl(acyl)silanes bearing a long alkyl chain in satisfactory yields. Allyl- and vinyl(acyl)silanes proved to have a poor reactivity in metathesis whatever the Grubbs catalyst used. However ring closing metathesis applied to bis(unsaturated) benzotriazole derivatives led to cyclic intermediates in very good yields. Cross-metathesis applied to an allysilane derived from benzotriazole led, after deprotection, to the expected bis(acylsilane). Allyl(dimethyl)(acyl)silanes exhibited an unexpected reactivity compared with the usual reactivity of acyl(trialkyl)silanes. UV irradiation of allyl(acyl)silanes gave 1-alkyl-2,2-diméthyl-6-oxa-2-sila-bicyclo[2. 2. 0]hexanes, a new type of bicyclic structure, by a totally regioselective intramolecular Paternò-Büchi reaction
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Nixon, Emily Cummings. « Silanes in sustainable synthesis : applications in polymer grafting, carbon dioxide capture, and gold nanoparticle synthesis ». Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45847.
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Vinyltrialkoxysilanes are grafted onto polyolefins via a radical mechanism; in a subsequent step, the pendant alkoxysilanes hydrolyze and condense upon exposure to water, resulting formation of crosslinks. Straight chain hydrocarbons were used as model compounds to investigate the regioselectivity of vinyltrimethoxysilane grafting. To stabilize the water-sensitive grafted products, the methoxy groups were substituted using phenyllithium. It was found that this reaction must be carried out for a minimum of three days to ensure full substitution. The grafted products were then separated on a weight basis using semi-preparative HPLC. Analysis of the di-grafted fraction using edited HSQC and HSQC-TOCSY NMR showed that radical propagation occurs via 1,4- and 1,5-intramolecular hydrogen shifts along the hydrocarbon backbone, resulting in multiple grafts per backbone. Post-combustion carbon capture targets CO₂ emissions from large point sources for capture and sequestration. A new class of potential carbon capture agents known as reversible ionic liquids (RevILs) has been synthesized and evaluated in terms of potential performance parameters (e.g. CO₂ capacity, viscosity, enthalpy of regeneration). These RevILs are silylated amines, which react with CO₂ to form a salt comprising an ammonium cation and a carbamate anion that is liquid at room temperature. Structural modifications of the basic silylamine skeleton result in drastic differences in the performance of the resulting RevIL. Systematic variation of the silylated amines allowed determination of a structure-property relationship, and continued iterations will allow development of an ideal candidate for scale-up. The properties and potential applications of gold nanoparticles (AuNP) are highly dependent on their size and shape. These properties are commonly controlled during liquid-phase synthesis through the use of capping agents, which must be removed following synthesis. Reverse micelles can also be used to control the morphology of AuNP during their synthesis. When RevILs are used in the formation of these reverse micelles, either as the disperse phase or as the surfactant, the built-in switch can be used to release the nanoparticles following their synthesis. This release on command could decrease the post-synthetic steps required to clean and purify AuNP prior to use. We have successfully synthesized AuNP using a number of different RevILs.
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Kunz, Andreas. « Untersuchungen zur Reaktionskinetik verschiedener Silizium-Precursoren bei hohen Temperaturen / ». Aachen : Shaker, 2001. http://www.gbv.de/dms/ilmenau/toc/332643166.PDF.
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Krüger, Christian. « Kolloidale Organisation auf lithographisch hergestellten Silanschichten neue Möglichkeiten der Strukturbildung auf Oberflächen / ». [S.l.] : [s.n.], 2001. http://ArchiMeD.uni-mainz.de/pub/2002/0027/diss.pdf.
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De, Waterbeemd Marion Van. « Silane Condensation to nanoparticles in suspension ». Thesis, University of Kent, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516211.
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Smith, David Murray. « Diode laser spectroscopy of silane plasmas ». Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259622.
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Vögler, Michael. « Zweifach Eisen-substituierte Silane, Silanole und Siloxane ». [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964213907.
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Vögler, Matthias. « Zweifach Eisen-substituierte Silane, Silanole und Siloxane ». [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964213907.
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Hanetho, Sidsel Meli. « Hybrid Aminopropyl Silane-based Coatings on Steel ». Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19540.
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Thin coatings applied to metals is a material-saving process to improve the surface properties such as abrasion and corrosion resistance of the substrate. Pure inorganic coatings are generally too thin to offer long-term protection, and thick coatings are prone to crack formation during processing. However, by incorporating an organic moiety, thicker and more flexible coatings can be developed. Hence sols and coatings based on 3-(aminopropyl)triethoxysilane, γ-APS, have been synthesized as part of the PhD work. Initially, pure inorganic alkoxide-based silica coatings were fabricated. These coatings displayed poor abrasion resistance and were poor alternatives with respect to corrosion protection of carbon steel. The need for thicker coatings was thus proposed, and hybrid inorganic-organic coatings were suggested as a probable solution. Thus in Paper I, hybrid inorganicorganic γ-APS-based sols were synthesized and characterized. Molar ratios of water (or solvent) and silane ratios and sol hydrolysis pH were varied. 29Si NMR was used to study the hydrolysis and condensation reactions. The kinetic mechanisms of the hydrolysis and condensation of the sols showed a difference in the structures formed depending on the water/silane ratio and the sol pH. Increasing the water/silane ratio promoted a faster condensation reaction as evidenced by the early evolution of more condensed species. Reducing the sol pH enabled the condensation reaction to slow down thus fascilitating a more complete hydrolysis reaction. Furthermore, hypostoichiometric sols were shown to consist of linear structures while stoichiometric and hyperstoichiometric sols were more cross-linked as evidenced by the higher viscosity and the combination of T2 and T3 species detected by 29Si NMR. In Paper II, coatings were fabricated from the sols described in Paper I. Transparent and homogeneous hybrid aminopropyl silane-based coatings on steel were prepared by the sol-gel method using the hydrolyzed γ-APS sols as precursors. The coatings were fabricated by dip coating, and the effect of pH, water/silane ratio and solvent/silane ratio during the coating process was investigated with respect to thermal stability, coating thickness, roughness, porosity, contact angle and abrasion resistance. The thickness of the coatings varied between 0.17 and 4.1 μm and was controlled by the preparation conditions of the sol as well as the viscosity of the sols. The coatings were in general smooth and the roughness in the order of a few nanometers. The contact angles with water of the coatings varied from 60 to 80° Organic pentadecane was shown to wet the coatings, which suggested that the coatings also displayed hydrophobic properties. The abrasion resistance improved with decreasing pH of the water used during hydrolysis of the silane. The coatings were characterized with respect to delamination and smearing. Thicker coatings were delaminated while thinner coatings were smeared and displayed lubricating properties. Gels of the hybrid aminopropyl silane-based sols were thermally stable up to 350°C, and the gels displayed a low pore volume and a low surface area. In Paper III, hybrid aminopropyl silane-based sols with a variation in the molar ratios of water and silane, the molar ratios of solvent and silane and pH, were applied as a bond coat to carbon steel substrates. Fracture strength, abrasion resistance and electrochemical polarization studies have been conducted on these bond coats. Furthermore, the bond coats were applied a top coat consisting of a polyaspartic paint, and the combination coatings were subsequently exposed to an ageing resistance test for 5 weeks. The bond coat-top coat combination coatings were demonstrated to significantly improve the corrosion protection behavior of carbon steel. The thickness of the bond coats varied from 0.35 to 4.1 μm, while the bond coat-top coat combination coatings were all in the range of 100 μm.
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Kaye, Philip Ian. « Silane, vinylsilane and vinylketone complexes of Rhodium ». Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265457.
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Briard, Renaud. « Renforcement du verre par un revêtement hybride en formulation aqueuse ». Rennes 1, 2004. http://www.theses.fr/2004REN10154.
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Nous avons étudié le renforcement du verre par le dépôt d'un film mince à partir d'un mélange d'organosilanes réactifs. Unfilm hybride organique/inorganique est créé par la réaction organique entre les fonctions amine et époxy d'une part et la réaction inorganique de condensation des silanols d'autre part. Les réactions conduisant à la formation du film ont été suivies par spectroscopie IR. Nous avons également caractérisé les propriétés mécaniques du film. Son module d'Young est de l'ordre de 5GPa et l'adhésion du film sur le verre et la cohésion au sein du revêtement sont élevées (supérieures à 2 J. M-2). Le renforcement mécanique apporté aux substrats revêtus est évalué par un test de flexion sur des échantillons préalablement indentés de façon contrôlée. Le revêtement étudié permet d'obtenir un renforcement de 75%. Nous discutons ensuite les différents mécanismes susceptibles d'expliquer le renforcement.
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Tilgner, Andreas. « Les polysilanes : spectroscopie optique et modélisation ». Grenoble 1, 1991. http://www.theses.fr/1991GRE10060.
Texte intégralRésumé :
Les polysilanes, une classe de polymeres sigma conjugues, ont ete caracterises par spectroscopie optique en solution vitreuse a basse temperature (absorption, fluorescence, hole burning, fluorescence resolue en temps). Les resultats experimentaux ont ete compares a des simulations numeriques. L'excitation electronique est bien decrite comme un exciton de frenkel, qui est faiblement couple aux mouvements des noyaux et qui est localise par un desordre continu distribue le long de la chaine. Le transport d'energie se fait a l'echelle de la picoseconde
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Thor, Christer. « Silent Install ». Thesis, Linköpings universitet, Interaktiva och kognitiva system, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-78632.
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Det här arbetet har gjorts på Infor, som idag har problem med krångliga och långsamma installationer av en produktsvit. Exjobbet beskriver en automatiserad installation av denna produktsvit med några få möjligheter till konfigurering. Skriptet som sköter installationen är skrivet i Ruby. Installationstiden kortades från 4-5 timmar till cirka 30 minuter.
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Behrens, Monika Art College of Fine Arts UNSW. « Silent bang ». Publisher:University of New South Wales. Art, 2007. http://handle.unsw.edu.au/1959.4/42557.
Texte intégralRésumé :
The research project uses still life as a means of exploring current events of violence and oppression. These events are represented through juxtaposing plastic toys with organic objects. The toys include a range of popular generic toys such as army men, cowboys and Indians and toy soldiers. The organic objects were selected for their relationship to the specific event being represented. The toys and organic objects were positioned to create interesting and logical compositions. Themes of the series include opposing objects and ideas pitched against each other such as plastic/organic, perpetrator/victim, violence/peacefulness and destruction/sustenance. Within each work the plastic toys take on the demeanor of the tyrant(s), whereas the organic objects adopt the role of the victim(s). The research project uses these themes to convey the message that violence is both a barbaric way of dealing with conflict and a senseless form of self-expression. I have used symbols and metaphors to build a visual language. For the language to be translated accurately a great deal of research has taken place into the appropriate still life objects for each work. Each work incorporates metaphors and or symbols for both the oppressor and victim within the event being represented. The studio outcome of this research project, Silent Bang, includes a series of highly detailed finished paintings of various scales. Silent Bang as a body of work is colourful and aims to be aesthetically pleasing in addition to conveying a powerful message that incites interpretation.
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Winde, Pierre, et David Lindström. « Silent Workspace ». Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-31185.
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Bartolomei, Suellen Signer. « Estudo de nanocompósitos formados por PLA e nanopartículas de celulose ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-04072016-152946/.
Texte intégralRésumé :
Devido à preocupação com o meio ambiente e o volume crescente de resíduos plástico em aterros sanitários, os polímeros biodegradáveis estão sendo estudados extensivamente. Um deles é o PLA. Apesar de possuir propriedades comparáveis a polímeros commodities e polímeros de engenharia, ainda é necessário melhorar certas características do PLA, como resistência ao impacto. Para isso, a nanocelulose (NC) pode ser usada sem alterações significativas na biodegradação polimérica. Este estudo teve como objetivo obter a nanocelulose, caracteriza-la e incorpora-la ao poli(ácido láctico) (PLA), assim como, estudar as propriedades térmicas, morfológicas e mecânicas do compósito obtido. A NC foi obtida por hidrólise ácida utilizando ácido fosfórico e posteriormente foi silanizada com três silanos distintos. As nanopartículas foram caracterizadas por Birrefringência, Microscopia Eletrônica de Transmissão (MET), Termogravimetria (TG), Potencial Zeta, Espectroscopia Vibracional de Absorção no Infravermelho com Transformada de Fourier (FTIR) e Difração de Raio X (DRX). Com as imagens obtidas pelo MET foi possível medir o tamanho das partículas de NC. E então obter a razão de aspecto de 82 e o limite de percolação de 1,1% em massa, confirmando a morfologia de nanofibra. De acordo as analises TG\'s, a presença de NC silanizada aumentou o início da degradação térmica. Os compósitos, contendo 3% em massa de NC, foram obtidos por fusão em câmara de mistura e moldados por injeção. Os compósitos foram caracterizados por FTIR, Cromatografia de Permeação em Gel (GPC), TG, Calorimetria Exploratória Diferencial (DSC), Microscopia Eletrônica de Varredura (MEV-FEG), Impacto e Tração. As análises dos compósitos mostraram que a NC atuou como agente de nucleação, facilitando a cristalização do PLA, além de a NC ter atuado como reforço na matriz polimérica melhorando as propriedades mecânicas.Due to concern for the environment and the growing volume of plastic waste in landfills, biodegradable polymers are being studied extensively. One of them is the PLA. Despite properties comparable to commodities polymers and engineering polymers, it is still necessary to improve certain characteristics of PLA, such as impact resistance. For this, the nanocelulose (CN) can be used without significant changes on the polymeric biodegradation. This study aimed to obtain nanocelulose, characterizes it and incorporates it to polylactic acid (PLA), even as, studies of thermal, morphological and mechanical properties of the composites processed. The CN was obtained by acid hydrolysis using phosphoric acid and it was, subsequently, silanized with three different silanes. The nanoparticles were characterized by Birefringence, Transmission Electron Microscopy (TEM), Thermogravimetry (TG), Zeta Potential, Spectroscopy Absorption Vibrational Infrared Fourier Transform (FTIR) and X-Ray Diffraction (XRD). By images taken by TEM was possible to measure the size of particles CN. So, obtain the aspect ratio of 82 and the percolation limit of 1.1 wt%, demonstrating morphology of nanofiber. According to TG analysis, the beginning of thermal degradation increased when CN Pure was compared with modified CN. The composite, containing 3 wt% CN, were obtained by melt in mixing chamber and then injection molded. The composites were characterized by FTIR, Gel Permeation Chromatography (GPC), TG, Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Impact and Tensile Strength. The results showed that the CN acts as a nucleating agent in PLA, facilitating the crystallization and acts as reinforcement in polymer matrix to improve the mechanical properties.
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Habekost, Luciano de Vargas. « Influência da incorporação de nanoparticulas e utilização de monômeros ácidos como agentes de união em cimentos resinosos ». Universidade Federal de Pelotas, 2011. http://repositorio.ufpel.edu.br/handle/ri/2260.
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Previous issue date: 2011-01-14The objective of this study was to investigate the influence of nanoparticle loading and the use of silane (TSPM), phosphate (PAM) or carboxylic (CAM) methacrylates as coupling agents on key properties of experimental resin luting agents. An experimental photocurable resin blend composed with 50 wt% of Bis-GMA and 50 wt% of TEGDMA was obtained. To study the influence nanoparticle loading, five different experimental resin luting agents were prepared with a total mass fraction of 60% of inorganic fillers. Silanated 2-μm barium borosilicate glass microparticles and 7-nm silica nanoparticles were used; the mass fraction of nanoparticles was set at 0 (control), 1 (G1), 2.5 (G2.5), 5 (G5) and 10% (G10). To study the influence of coupling agents, the resin blend was loaded with a 60% mass fraction of inorganic fillers (59/1 mass ratio of micro/nanoparticles) of Ba-B-Al-Si glass and colloidal silica coated with 5 wt% of TSPM, PAM or CAM; no filler treatment was performed in the control group. The properties evaluated were flexural strength () and modulus (Ef), Knoop hardness number (KHN), and film thickness (FT). Dispersion/interaction of particles with the resin phase was assessed by scanning electron microscopy (SEM).The degree of conversion (DC) was evaluated only to study the influence of coupling agents. Data were submitted to statistical analysis (5%). Results for nanoparticle loading: for , G1 > G2.5 = G5 = G10, and control > G10. For Ef, G2.5 > control = G1 > G5 > G10. For KHN, G5 = G10 > control = G1 = G2.5. For FT, control = G1 < G5 = G10, and G2.5 < G10. Incorporation of nanoparticles was associated with observation of clusters in the SEM analysis. Results for different coupling agents: for and Ef, TSPM > CAM > control > PAM. For KHN, TSPM > CAM > PAM = control. For FT, TSPM < control < CAM < PAM. The SEM analysis revealed clustering of nanoparticles for all groups and better interaction between the organic-inorganic phases for TSPM and CAM. No significant differences in DC were observed. The results demonstrated that moderate incorporation of silanated silica nanoparticles may improve the properties of hybrid resin cements. However, mass fraction above 2.5% had a detrimental effect on the luting agent properties and the increase of clusters is associated with the increase of nanoparticles. The use of TSPM generated agents with improved properties as compared with the acidic methacrylates, with CAM showing better performance than PAM. The use of PAM generated agents with properties usually poorer compared with the material with no coupling agent.
O objetivo deste estudo foi investigar a influência da incorporação de nanopartículas e o uso de silano (TSPM), monômero ácido fosfatado (PAM) ou monômero ácido carboxilado (CAM) como agentes de união nas propriedades de cimentos resinosos experimentais. Uma matriz resinosa fotopolimerizável modelo foi desenvolvida com 50% de Bis-GMA e 50% de TEGDMA. Para observar o comportamento da incorporação de nanopartículas, cinco cimentos resinosos experimentais foram preparados pela adição de 60% (em massa) de micropartículas de bário borosilicato de vidro (2μm) e nanopartículas de sílica coloidal (7nm). As nanopartículas foram utilizadas nas seguintes proporções (em massa): 0 (controle), 1 (G1), 2.5 (G2.5), 5 (G5) e 10% (G10). Para estudar a influência dos agentes de união, 60% (em massa) de partículas inorgânicas (59/1 de micro/nanopartículas) de vidro de Ba-B-Al-Si e sílica coloidal, cobertas com 5% de TSPM, PAM ou CAM, foram acrescidas à matriz resinosa; o grupo controle foi composto por partículas não tratadas. As propriedades avaliadas foram resistência flexural (), módulo de elasticidade (Ef), número de dureza Knoop (KHN) e espessura de película (FT).A dispersão/interação das partículas com a fase resinosa foi avaliada com microscópio eletrônico de varredura (MEV). O grau de conversão (DC) foi avaliado somente para estudar a influência dos diferentes agentes de união. Os dados foram submetidos à análise estatística (5%). Resultados para incorporação de nanopartículas: para , G1 > G2.5 = G5 = G10 e controle > G10. Para Ef, G2.5 > controle = G1 > G5 > G10. Para KHN, G5 = G10 > controle = G1 = G2.5. Para FT, controle = G1 < G5 = G10 e G2.5 < G10. Nas análises em MEV, a presença de aglomerados foi associada à incorporação de nanopartículas. Resultados para a utilização de diferentes agentes de união: para e Ef, TSPM > CAM > controle > PAM. Para KHN, TSPM > CAM > PAM = controle. Para FT, TSPM < controle < CAM < PAM. As análises em MEV revelaram aglomerados de nanopartículas em todos os grupos e melhor interação entre as fases orgânica/inorgânica para TSPM e CAM. Não foram observadas diferenças para o DC. Os resultados demonstraram que a incorporação moderada de nanopartículas de sílica silanizada pode beneficiar as propriedades dos cimentos resinosos híbridos. Entretanto, proporções de nanopartículas acima de 2,5% possuem um efeito prejudicial nas propriedades destes cimentos, e seu aumento está associado com o aumento da presença de aglomerados. O uso de TSPM gerou cimentos com melhores propriedades quando comparado ao uso de monômeros ácidos, o CAM demonstrou melhor desempenho que o PAM. O uso do PAM gerou cimentos com propriedades inferiores a cimentos sem a utilização de agentes de união.
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Kumar, Vivek. « IMPLANT ANNEALING OF SiC IN A SILANE AMBIENT ». MSSTATE, 2001. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04102001-151957/.
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The goal of this research project was to develop a new implant annealing process using silane overpressure to maintain crystal integrity. After ion implantation the surface of the SiC wafer is damaged due to high energy of the implant ions. In addition the doping activation is very low. To overcome these problems a new implant annealing process was developed to rectify the surface damage and increase the dopant activation. SiC implant annealing was performed in the silicon carbide (SiC) chemical vapor deposition (CVD) reactor in the Emerging Materials Research Laboratory (EMRL) at Mississippi State University. A process was developed to eliminate surface step bunching, which is evident in argon annealed crystals. The process gas used in the new technique was silane (3 % SiH4 in 97% UHP Ar). The anneal run time was 30 minutes with argon flow rate at 6 slm and silane flow rate at 6 sccm. SiC material (n and p type epitaxial layers) and devices (JBS Diodes and LDMOSFET?s) were annealed using the silane over pressure developed during this research. The process results were characterized using tools such as optical micrograph, capacitance-voltage (C-V), Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). These characterization tools were mainly used to determine the surface roughness of the SiC crystal and the dopant activation after annealing. As compared to an Ar anneal, the SiC material and devices annealed in the silane ambient had a better surface. An empirical process chemistry model was developed to support the experimental results. The model developed showed that the partial pressure of Si is greater than the vapor pressure of SiC in the substrate. Thus it is believed that the partial pressure of Si suppressed any Si out-diffusion from the SiC substrate, thereby maintaining the crystal surface integrity. The model also provided silane flow rates for higher temperature anneals which may be necessary to fully activate other ion species.
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Velamakanni, Aruna M. « Functional silane based polymers for sensing and separations / ». View online ; access limited to URI, 2006. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3248243.
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ZHU, DANQING. « CORROSION PROTECTION OF METALS BY SILANE SURFACE TREATMENT ». University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1115992852.
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XU, MAN. « PASSIVATION OF BATCH-GALVANIZED STEEL BY SILANE TREATMENT ». University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1195660288.
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Hofmann, Marco. « Ferriomethyl- und Wolframiomethyl-substituierte Silane, Silanole und Siloxane ». Doctoral thesis, [S.l.] : [s.n.], 2001. https://nbn-resolving.org/urn:nbn:de:bvb:20-1181579.
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Das Interesse an Übergangsmetall-substituierten Siloxanen ist in den vergangenen Jahren stark angewachsen. Dies ist vor allem darauf zurückzuführen, dass diesen Systemen eine wichtige Modellfunktion für auf Silica-Oberflächen verankerte, katalytisch aktive Übergangsmetallkomplexe zukommt, die eine Vielzahl organischer Reaktionen katalysieren und dabei sowohl die Vorteile der Homogenkatalyse als auch der Heterogenkatalyse in einem einzigen System vereinen. Weiterhin kommt ihnen auch eine wichtige Bedeutung als Vorstufen zur Darstellung von Silicon-Polymeren und Keramiken zu, die definierte Metallzentren in ihrem Polymer-Grundgerüst enthalten und somit als neue Werkstoffe mit hoher mechanischer und thermischer Stabilität sowie ausgezeichneten leitenden Eigenschaften dienen können. Metallosiloxane mit einer direkten Metall-Silicium-Bindung können über die entsprechenden Metallo-silanole generiert werden, die seit Beginn der 90er Jahre eine intensivere Bearbeitung erfahren. In dieser Arbeit wurden die ersten Vertreter von Metallo-silanolen dargestellt und bezüglich ihrer Reaktivität untersucht, in denen das Metall- und Siliciumatom durch einen Alkylidenspacer getrennt ist. Es wurde zunächst eine Reihe von C5R5(OC)2FeCH2-substituierten Silanolen über die Et3N-assistierte Hydrolyse von Ferriomethyl-chlorsilanen bzw. Oxygenierung von Si-H-funktionellen Ferriomethyl-silanen mit Dimethyldioxiran dargestellt. Die Stabilisierung durch das Metallfragment in β-Stellung zur Silanoleinheit erweist sich ebenfalls hinreichend für die Darstellung von Ferriomethyl-silandiolen und –silantriolen, wie anhand der Darstellung von Cp(OC)2Fe-CH2-Si(R)(OH)2 (R = Me, OH) nachgewiesen werden konnte. Allerdings zeigen diese Vertreter im Vergleich zu ihren Analoga mit direkter Fe-Si-Bindung eine z.T. deutlich erhöhte Eigenkondensationsneigung. Die Röntgenstrukturanalysen der Ferriomethyl-diorganosilanole C5R5(OC)2Fe-CH2-Si(Me)(R’)OH belegen deren Aggregation zu Tetrameren bzw. unendlichen Ketten im Festkörper über starke intermolekulare OH...O-Wasserstoffbrückenbindungen. Durch Et3N-assistierte Kondensation mit Organochlorsilanen, wie z.B. Me2Si(H)Cl lassen sich kontrolliert Ferriomethyl-substiuierte Di-, Tri- und Tetrasiloxane generieren. Auch der Aufbau von mehrkernigen Heterosiloxangerüsten ist möglich, wie exemplarisch anhand der Synthese von Cp(OC)2Fe-CH2-SiMe2O-M(Cl)Cp2 (M = Ti, Zr) überprüft wurde. Weiterhin können auch Modifikationen am Metallfragment vorgenommen werden, wie der photochemisch induzierte CO/PR3-Austausch an Cp(OC)2-CH2-SiMe2OH beweist. Die synthetisierten Ferriomethyl-siloxane mit δ-ständiger Si-H-Funktion eignen sich für weitere Umsetzungen, wie z.B. der oxidativen Addition der Si-H-Funktion an ungesättigte Metallfragmente. So lassen sich das Tri- bzw. Tetrasiloxan Cp(OC)2Fe-CH2-Si(R)(OSiMe2H)2 (R = Me, OSiMe2H) durch UV-Bestrahlung unter CO-Eliminierung glatt in die Cyclo(ferra)siloxane Cp(OC)(H)Fe-SiMe2-OSi(Me)(R)-OSiMe2 überführen. Abschließend wurde überprüft, ob sich die Chemie der Ferriomethyl-silanole auch auf andere Übergangsmetallfragmente übertragen lässt. Hierbei konnten Wolframiomethyl-silanole mit dem Cp(OC)2(Me3P)WCH2-Fragment dargestellt werden, wobei sich, im Gegensatz zu den Eisenvertretern, die Darstellungsmethode der Oxygenierung von Si-H-funktionellen Vorläufern als vorteilhafter erweistThe interest in transition metal substituted siloxanes has rapidly grown in recent years. This is mainly due to their ability to serve as model systems for catalytically active transition metal complexes immobilized on a silica surface combining the advantages of homogeneous as well as those of heterogeneous catalysis in one system. In addition, these systems are also considered as precursors in the production of silicon polymers and ceramics with well-defined metal centres in the polymer backbone and can so be applied as new materials with good mechanical and thermal stability and excellent conducting properties. Metallo-siloxanes with a direct metal-silicon bond can be generated via the corresponding metallo-silanols which raised a greater attention in the last ten years. In this work the first examples of metallo-silanols have been synthesized and studied in which the metal and silicon atom are separated by an alkylidene spacer group. A number of C5R5(OC)2FeCH2-substituted silanols has been generated via Et3N-assisted hydrolysis of ferriomethyl-chlorosilanes and oxygenation of Si-H-functional ferriomethyl-silanes with dimethyldioxirane, respectively. The stabilizing effect of the metal fragment in β-position to the silanol unit is sufficient for the isolation of ferriomethyl-silanediols und –silanetriols as could be demonstrated in the synthesis of Cp(OC)2Fe-CH2-Si(R)(OH)2 (R = Me, OH). However, these compounds show an enhanced tendency to self-condensation compared to their analogues with a direct metal-silicon bond. The X-ray structure analyses of the ferriomethyl-diorganosilanols C5R5(OC)2Fe-CH2-Si(Me)(R’)OH show their aggregation to tetramers or infinite chains in the solid state, respectively, via strong intermolecular OH...O hydrogen bonds. Ferriomethyl-substiuted di-, tri- and tetrasiloxanes can be generated by controlled Et3N-assisted condensation with organochlorosilanes, e.g. Me2Si(H)Cl. Even binuclear heterosiloxanes can be synthesized as was proved by the synthesis of Cp(OC)2Fe-CH2-SiMe2O-M(Cl)Cp2 (M = Ti, Zr). In addition, there are also modifications at the metal fragment possible like the photochemically induced CO/PR3 substitution at Cp(OC)2-CH2-SiMe2OH. Ferriomethyl-siloxanes with a Si-H function in δ-position are suitable for further modifications, e.g. oxidative addition of the Si-H function to electronically unsaturated metal fragments. UV irradiation of the tri- and tetrasiloxanes Cp(OC)2Fe-CH2-Si(R)(OSiMe2H)2 (R = Me, OSiMe2H) leads to CO elimination producing the cyclo(ferra)siloxanes Cp(OC)(H)Fe-[SiMe2-OSi(Me)(R)-OSiMe2]. Finally it was examined if the chemistry of ferriomethyl-silanols can be transferred to compounds with other transition metal fragments. Tungsteniomethyl-silanols with a Cp(OC)2(Me3P)WCH2 fragment can be generated, whereas in contrast to the synthesis of ferriomethyl-silanols, the oxygenation method via Si-H functional precursors is more favourable
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Bandeira, Barbara Eugenia. « Combination of orientation with silane crosslinking of polyethylene ». Thesis, University of Leeds, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531640.
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