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1
Wilkinson, Susan Anne. "Aspects of radiation curing". Thesis, City University London, 1989. http://openaccess.city.ac.uk/7720/.
Testo completoAbstract (sommario):
The electron beam induced polymerisation of dialkyltin diacrylates, as well as the UV and electron beam induced polymerisation of some novel silicon containing acrylates are discussed. The reactivity and film forming properties of these materials are compared with that of some commercial diluents such as, tripropyleneglycol diacrylate, TPGDA and trimethylolpropane triacrylate, TMPTA. Mechanistic studies concerning the initiation of free radical polymerisation of the acrylate ester, isodecylacrylate, IDA on electron beam irradiation are presented. Addition of electron and hole scavengers revealed that slow electrons contribute significantly to the initiation of electron beam induced polymerisation of acrylate esters. The film forming properties of phenyl acrylate and mono-, di- and tri- halophenyl acrylates on exposure to electron beam irradiation are evaluated in terms of their ability to produce tackfree films. The sensitivity of catechol diacrylate compared with t-butyl catechol diacrylate is also presented. Mechanistic studies concerning the initiation of both UV and electron beam induced cationic polymerisation of 3,4-epoxycyclohexylmethyl-31,41 -epoxycyclohexanecarboxylate, with the aid of diphenyliodonium hexafýuorophosphate, triphenylsulphonium hexafluorophosphate and (n -2,4-cyclopentadien- I-yl) [(I, 2,3,4,5,6-n) (-I-methylethyl) benzene] -iron(I+) hexafluorophosphate, as well as the radiolysis of 6,7-epoxy- 3,7-dimethyloctylacrylate in the presence of diphenyliodonium hexafluorophosphate are presented. The decomposition of the salts was monitored in situ by infrared and UV spectroscopy and hydrogen fluoride is credited as the true initiator of the cationic polymerisation of epoxides in an open system. The UV photolysis of the aforementioned onium salts led to the production of volatiles, resulting in the polymerisation of thin films of 3,4-epoxycyclohexylmethyl-31,41 - epoxycyclohexanecarboxylate, providing further evidence of hydrogen fluoride evolution. The use of FTIR- photoacoustic spectroscopy was proven to be an invaluable tool in monitoring the polymerisation of thin epoxide or acrylate films on an opaque substrate.
2
Khan, Niaz Ahmad. "Aspects of radiation curing". Thesis, City University London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241483.
Testo completo
3
Zilic, Elvis. "Radiation curing and grafting of charge transfer complexes". Thesis, View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/19385.
Testo completoAbstract (sommario):
Charge transfer (CT) complexes have been used in a number of radiation polymerisation processes including grafting and curing. The complexes studied include donor (D) monomers like vinyl ethers and vinyl acetate (VA) with acceptor (A) monomers such as maleic anhydride (MA). Both UV and EB have been utilised as radiation sources. The complexes are directly grafted to these substrates in the presence of radiation. The complexes yield novel copolymers when radiation cured with concurrent grafting improving the properties of the finished product. The term cure grafting has been proposed for this concurrent grafting process. Studies in basic photografting work to complement the cure grafting have been proposed. The role of solvent in grafting is discussed, particularly the effect of aromatics in photografting to naturally occurring trunk polymers like wool and cellulose. The effect of the double bond molar ratio (DBMR) of the DA components in grafting is examined. The ultraviolet (UV) conditions for gel formation during photografting, hence the importance of homopolymer yields in these processes is reported. A plausible mechanism to explain the results from this photografting work is proposed. The significance of these photografting studies in the related field of curing, especially in UV and ionising radiation (EB) systems, is discussed. EB curing and cure grafting of charge transfer (CT) monomer complexes is investigated. The EB results are compared with UV curing and cure grafting of the same complexes. The work has been extended to include EB/UV curing and cure grafting of thiolene systems. The significance of these results in the potential commercial application of these complexes is discussed. Variables affecting the UV/EB curing and cure grafting of thiolenes on cellulose have been studied. These include effect of varying the type of olefin, increasing the functionality of the thiol, use of acrylate monomers and oligomers in hybrid systems, altering the surface structure of the cellulose and finally the role of air in these processes particularly with EB. Photopolymerisation of the thiol-enes in bulk has also been investigated. The thesis content is based on the published work of 14 research papers over the course of the project.
4
Zilic, Elvis. "Radiation curing and grafting of charge transfer complexes". View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/19385.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--University of Western Sydney, 2008.Thesis submitted to the University of Western Sydney, College of Health and Science, School of Natural Sciences, in fulfilment of the requirements for admission to the Doctor of Philosophy. Includes bibliography.
5
Herlihy, Shaun Lawrence. "Factors influencing the efficiency of photoinitiation in radiation curable ink formations". Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360974.
Testo completoAbstract (sommario):
In an effort to be able to use photoinitiators to their maximum potential, the sequence of events that occurs in an ink formulation during the UV curing process has have been studied and information presented to allow more effective formulation. Emphasis has been placed on highlighting the variables that have the greatest impact both on photoinitiator efficiency and on the suitability of individual photoinitiators and synergists for use in particular applications. These variables were found to be photoinitiator thermal stability, UV light utilisation, reaction mechanisms and cure reactivity. A wide range of photoinitiators and synergists were investigated using thermogravimetric analysis (TGA) and thermogravimetric analysis-mass spectroscopy (TGA-MS) to define both their thermal stability and whether under heating they thermally decompose or merely evaporate. Differential photocalorimetry (DPC) was used to determine which wavelengths from a typical medium pressure mercury curing lamp are the most important for providing cure, with both theoretical and practical methods being used to define the extent to which these wavelengths penetrate into pigmented and non-pigmented coatings. A procedure was devised and validated for this purpose. The reaction mechanism and photodecomposition products of a range of photoinitiators were investigated using gas chromatography-mass spectroscopy (GC-MS) and radical trapping experiments. The reaction mechanisms are discussed in terms of available literature knowledge. Evidence is also presented suggesting that, with only particular exceptions, cleavage photoinitiators can also react by a hydrogen abstraction mechanism in the presence of an amine synergist. A real time infrared spectrometer (RTIR) was set up and a method validated for following the UV curing reaction through changes in the acrylate double bond concentration. The advantages and disadvantages of this instrument are discussed in terms of other similar instruments reported in the literature, and the technique subsequently used to measure the reaction rates of a wide range of photoinitiators. Other factors such as photoinitiator concentration, amine synergist type I level and formulation viscosity were also investigated to determine their influence on the cure process.
6
JANSEN, JOSE U. "Síntese e caracterização de verniz eletroisolante para cura dual UV/termica". reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11374.
Testo completoAbstract (sommario):
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
7
Hamzah, Hazira. "Photochemistry and photopolymerisation of novel sustituted 2-methylanthraquinones in radiation curing". Thesis, Manchester Metropolitan University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505327.
Testo completo
8
Nguyen, Duc Ngoc. "Effects of solvents and comonomers on radiation curing and grafting processes". Thesis, View thesis, 2002. http://handle.uws.edu.au:8081/1959.7/712.
Testo completoAbstract (sommario):
A study has been made on the irradiation induced grafting of MMA to PPE and cellulose subtrates in the presence of various solvents and Irgacure 819 photoinitiator, a new photoinitiator on the market at the commencement of this project. UV is the main irradiation source used. The grafting yields have been found to vary with parameters such as the subtrate types and thickness, MMA concentration, solvents used, Irgacure 819 concentration and UV doses. For the cellulose subtrate, good grafting yields were obtained only when solvents such as methanol and DMF were used. On the contrary, MMA could graft to PPE with or without solvents, although high grafting yields were achieved in the presence of methanol, DMF and other chlorinated solvents. The solvent effects on the grafting process of MMA to PPE and cellulose subtrates were attributed to the wetting and swelling effects by the solvents as well as the Trommsdorff effect. During the course of this study, a comparison in the performance between Irgacure 819 and other photoinitiators (PIs) was also carried out. A study was made of the UV radiation induced grafting of styrene to PPE subtrate with EP vinyl monomers and vinyl ethers as comonomers. The possibility of spontaneous polymerization of styrene/EP vinyl monomer mixtures under the influence of UV radiation was also investigated. Grafting yields were found to vary with the comonomer types and their concentrations, the presence or absence of solvents and additives such as Irgacure 819 photoinitiator, K185 cationic photoinitiator, mineral acids and CT complexes. In addition, the composition of grafted subtrates was studied by using the FT-IR spectroscopy technique
9
Nguyen, Duc Ngoc. "Effects of solvents and comonomers on radiation curing and grafting processes /". View thesis, 2002. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20031008.120616/index.html.
Testo completoAbstract (sommario):
Thesis (PhD) -- University of Western Sydney, 2002."A candidate for the degree of Doctor of Philosophy." "A thesis submitted in the School of Science, Food and Horticulture, University of Western Sydney." "June 2002" Bibliography: leaves 303 - 305.
10
Merritt, Laura. "The application of radiation curing to the production of security printing ribbons". Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244332.
Testo completo
11
Pullen, Graeme K. "2-substituted anthraquinones as photoinitiators of free radical polymerisation". Thesis, Manchester Metropolitan University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320492.
Testo completo
12
Fatnasare, Ike S. "A study of the effect of water-pick up of UV curable offset ink on its curing time and its end use properties /". Online version of thesis, 1993. http://hdl.handle.net/1850/11169.
Testo completo
13
BARDI, MARCELO A. G. "Avaliação do impacto ambiental gerado por tintas gráficas curadas por radiação ultravioleta ou feixe de elétrons em materiais para embalagens plásticas convencionais ou biodegradáveis pós-consumo". reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23653.
Testo completoAbstract (sommario):
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-04-10T14:21:53Z
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
14
Bergman, Gerald R. "Evaluation of Exposure to Optical Radiation in Medical Diagnostics and Treatment". University of Toledo Health Science Campus / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=mco1095952844.
Testo completo
15
Hu, Qi-Ang. "UV curable resin for ink jet printing on textile substrates". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/8550.
Testo completo
16
Jabbari, E. "Investigation of the heating and curing rate of polymeric materials with thermal energy, continuous and pulsed microwave radiation". Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/64570.
Testo completoAbstract (sommario):
The purpose of this work was to study the heating and curing rate of polymers with continuous and pulsed microwave radiation and compare with conventional thermal energy. The heating rate of poly(ethylene glycol) and poly(propylene glycol) has been studied as a function of molecular weight with pulsed as well as continuous microwave radiation, at constant average power. The curing rate of poly(amic acids) have also been studied with thermal energy, continuous and pulsed microwave radiation to better understand the interaction between pulsing the microwave and the polymeric material.
Results from the heating rate studies indicate that the enhancement in heating rate with pulsed microwave radiation depends on the low frequency absorption spectrum (i.e., less than 10,000 Hz) of the polymer. The heating rate of poly(propylene glycol), which has a low frequency absorption, was enhanced by pulsing the microwave energy whereas the heating rate of poly(ethylene glycol), which does not have a low frequency absorption, remained the same when compared to continuous wave. Also results from the curing rate studies with poly(amic acids) indicate that the enhancement in curing rate observed in samples cured by microwave radiation as opposed to those thermally cured may be partially due to microwave power distribution in the cavity. This has been tested by agitating the sample to reduce any temperature gradient arising from the power distribution in the cavity. According to the experimental results, as the agitation rate was increased, the rate of imidization of poly(amic acids) with microwave radiation approached the rate of thermal imidization, at constant temperature. However, more research is required to clarify this complex phenomenon.Master of Science
17
Skelte, Gabrielle. "Enhancing colour development of photochromic prints on textile : Physical stabilisation during UV-radiation exposure". Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12373.
Testo completoAbstract (sommario):
Textile UV-radiation sensors has lately been introduced to the field of smart textiles. Inkjet printing has been used as means of application due to the effective and resource efficient process. UV-LED radiation curing has been used in combination with inkjet printing in favour of low energy requirements, solvent free solution and reduced risk of clogging in the print heads. The problems arising when exposing photochromic prints to UV-radiations are that oxygen inhibition during the curing and photo-oxidation in the print reduces the prints ability to develop colour. It is the oxygen in the air in combination with UV-radiation that gives the photo-oxidating behavior. The aim of the study is to with the aid of physical protection reduce the effect of oxygen inhibition and photo-oxidation in the prints. Three types of physical treatments were used, wax coating, protein based impregnation and starch based impregnation. Treatments were applied before curing as well as after curing and the colour development after activation during 1 min of UV-radiation was measured with a spectrophotometer. Multiple activations were also tested to see how the treatments affected the fatigue behaviour of the prints over time. The aim was to have as high colour development as possible reflecting reduced oxygen inhibition and photo-oxidation. Results showed significantly higher colour development for samples treated with wax and whey powder before curing, but reduced colour development for amylose impregnation. Over time whey powder before curing showed highest colour development due to highest initial colour development. Lowest fatigue was seen for washed samples containing the chemical stabiliser HALS, showing an increased colour development. In reference to earlier studies the protective properties of wax and whey powder is due to their oxygen barrier properties protecting the print. The tested treatments have shown that it is possible to reduce the effect of photo-oxidation during curing leading to prints giving higher colour development. This gives a great stand point when improving existing and future application of photochromic prints on textiles.
18
Lemos, Ana Rita Santos. "Desenvolver um sistema de envernizamento por cura ultravioleta para parquet e soalho de madeira". Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16784.
Testo completoAbstract (sommario):
mestrado em Engenharia QuímicaDe maneira a proteger aos pavimentos de madeira é essencial revestir este material com um verniz, criando uma barreira protetora contra os diversos agentes atmosféricos, biológicos e químicos que possam danificá-la. Para formar esta barreira, o verniz passa por uma etapa de cura, após a sua aplicação no substrato, onde o filme líquido se transforma numa película sólida protetora. Existem vários métodos de cura de vernizes, nomeadamente cura térmica, cura química ou cura por radiação ultravioleta (fotopolimerização). O interesse na cura de vernizes com radiação ultravioleta tem vindo a aumentar devido à rapidez deste processo, assim como as propriedades que confere ao substrato. No caso da cura por ação da radiação ultravioleta, a formação da película sólida inicia-se quando o revestimento é irradiado com luz ultravioleta. Um verniz para cura com radiação ultravioleta é constituído por resinas, fotoiniciadores, solventes (solventes orgânicos ou água) e aditivos. Um dos componentes mais importantes é a resina, pois esta confere à película propriedades como dureza, resistência física e química, para além de determinar a velocidade de cura. Para iniciar a polimerização é necessária a presença de fotoiniciadores, são estes que, após exposição à radiação, formam espécies reativas que iniciarão a reação. Por fim, são adicionados aditivos à formulação de um verniz com o objetivo de melhorar certas propriedades e prevenir imperfeições no revestimento do pavimento. Neste trabalho desenvolveu-se um verniz aquoso de cura por ação de radiação ultravioleta, para manutenção in situ de pavimentos de madeira. Este produto tem como vantagem a rapidez do processo de cura, assim como a redução de emissão de gases de efeito de estufa. Para isso, desenvolveram-se várias formulações e analisaram-se diferentes componentes até se encontrar os mais adequados. Posteriormente, as formulações foram aplicadas em diversos substratos de madeira e foram efetuados testes para avaliar características como a sua dureza e a aderência. Este estudo permitiu encontrar uma formulação que cumpre os requisitos desejados, um verniz que se traduz num revestimento com excelente dureza e com tempos de secagem física e de cura reduzidos.
To protect wooden floors it’s essential to use a coating that creates a protecting barrier against atmospheric, biological and chemical agents that can damage the wood. To form this barrier, the coating needs to be cured after application, where the liquid film turns into a solid protective film. The curing of the coating can be activated by heat (heat curing), by adding a chemical agent (chemical curing) or by ultraviolet irradiation. The interest in ultraviolet radiation curing has been increasing due to the speed of this process as well as the properties granted to the surface. In curing using ultraviolet radiation, the formation of the film begins when the coating is hit by the radiation irradiated by lamps. This kind of coating has a formulation that consists of resins, photoinitiators, solvents (organic solvents or water) and additives. One of the most important components of a ultraviolet cured coating it’s the resin, it provides the film such proprieties such as hardness, physical and chemical resistance, in addition to defining the curing rate. To initiate polymerization, the presence of photoinitiators in the formulation is necessary, because when this component is exposed to ultraviolet radiation, forms reactive species that initiate the reaction. Lastly, to the formulation is added additives, which improve certain properties and prevent coating defects. In this work, it was developed a water-based coating with ultraviolet radiation curing to be used in in situ maintenance of wooden flooring. This product has the advantage of the speed of the curing process as well as the reduction of the emission of greenhouse gases. Various formulations were developed and different components were analyzed to find the most appropriate to the system. After application in wooden substrates, test were performed to analyze certain characteristics as hardness or adhesion. Finally, it was developed a formulation with excellent hardness and reduced time for the curing process.
19
Slopek, Ryan Patrick. "In-situ Monitoring of Photopolymerization Using Microrheology". Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7194.
Testo completoAbstract (sommario):
Photopolymerization is the basis of several multi-million dollar industries including films and coating, inks, adhesives, fiber optics, and biomaterials. The fundamentals of the photopolymerization process, however, are not well understood. As a result, spatial variations of photopolymerization impose significant limitations on applications in which a high spatial resolution is required.
To address these issues, microrheology was implemented to study the spatial and temporal effects of free-radical photopolymerization. In this work a photosensitive, acrylate resin was exposed to ultraviolet light, while the Brownian motion of micron sized, inert fluorescent tracer particles was tracked using optical videomicroscopy. Statistical analysis of particle motion yielded data that could then be used to extract rheological information about the embedding medium as a function of time and space, thereby relating UV exposure to the polymerization and gelation of monomeric resins.
The effects of varying depth, initiator concentration, inhibitor concentration, composition of the monomer, and light intensity on the gelation process were studied. The most striking result is the measured difference in gelation time observed as a function of UV penetration depth. The observed trend was found to be independent of UV light intensity and monomer composition. The intensity results were used to test the accuracy of energy threshold model, which is used to empirically predict photo-induced polymerization.
The results of this research affirm the ability of microrheology to provide the high spatial and temporal resolution necessary to accurately monitor the photopolymerization process. The experimental data provide a better understanding of the photo-induced polymerization, which could lead to expanded use and improved industrial process optimization. The use of microrheology to monitor photopolymerization can also aid in the development of predictive models and offer the ability to perform in-situ quality control of the process.
20
Tehfe, Mohamad Ali. "Etude de nouveaux systèmes amorceurs pour des polymérisations radicalaires ou cationiques". Phd thesis, Université de Haute Alsace - Mulhouse, 2011. http://tel.archives-ouvertes.fr/tel-00694133.
Testo completoAbstract (sommario):
Le point clé des polymérisations radicalaires et/ou cationiques réside dans la génération des radicaux et/ou des cations qui amorcent la réaction. Ces derniers sont formés par transformation, via absorption de lumière, d'un composé photosensible. Puisque la majorité des réactions de polymérisation se produisent en système ouvert, on conçoit l'importance de trouver des solutions aux inconvénients liés à la présence de l'air lors de la réticulation. Durant ce travail, de nouvelles séries de molécules de type silanes, germanes, complexes boranes ... ont été examinées. On va s'intéresser aussi aux systèmes d'amorçage de type I et II. Nous nous intéresserons aussi à la polymérisation induite par la lumière visible ou solaire. Notre objectif consiste à développer des systèmes dont la sensibilité spectrale s'étend vers de grandes longueurs d'onde. Les molécules étudiées au cours de ce travail semblent être très favorables en tant que photoamorceurs ou co-amorceurs pour la polymérisation radicalaire ainsi que pour la polymérisation cationique. La plupart de ces structures se sont montrées plus efficaces que les références utilisées. Le travail de cette thèse s'articule autour de deux grandes parties : La première partie relative à la polymérisation radicalaire contient également une étude bibliographique et se divise en trois chapitres. La deuxième partie relative à la polymérisation cationique se divise en sept chapitres. Une annexe sera donnée à la fin de ce manuscrit et regroupe les différentes techniques expérimentales.
21
Zubkova, Ekaterina. "Posouzení vlivu uzavíracích nátěrů a lakovaných povrchů na trvanlivost betonových výrobků". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372230.
Testo completoAbstract (sommario):
This diploma thesis is focused on studying the influence of different types of surface treatments on vibropressed product. The main goal is to characterize surface treatments consisting of application of surface coatings that are hardened by infrared or ultraviolet radiation. Theoretical part gives specifications already known methods for surface finishing. Briefly describes selected types of prefabricated concrete parts and specificate the requirements for these products. It also describes used test methods. The experimental part was aimed at establishing the effectiveness of changing properties concrete products by adding coatings on their surface. This was achieved by testing the properties of concrete paving blocks with modified surfaces and testing of reference blocks that did not have any surface treatment followed by mutual comparison of the results.
22
Martin, Arnaud. "Optimisation de fibres de carbone pour leur application à des composites hautes-performances à matrice organique polymérisés par voie radicalaire sous rayonnement". Thesis, Reims, 2014. http://www.theses.fr/2014REIMS037.
Testo completoAbstract (sommario):
La polymérisation amorcée sous rayonnement ionisant est un procédé hors-autoclave prometteur pour la fabrication de structures de matériaux composites à hautes performances. Les faisceaux d’électrons en particulier peuvent amorcer les processus de polymérisation radicalaire de monomères à base acrylate. Cependant, les matériaux composites obtenus présentent une faiblesse au niveau des propriétés transverses et en particulier dans le sens perpendiculaire aux fibres de carbone. L’objectif de ce projet de recherche vise à améliorer les performances transverses de ces composites par le biais d’une modification de la surface des fibres de carbone. Cet objectif doit être atteint en premier lieu par la réalisation d’une étude de l’influence de la chimie présente à la surface des fibres de carbone sur la polymérisation amorcée sous rayonnement ionisant des matrices de ces composites. Nous avons cherché à comprendre comment la polymérisation intervenant à l’interface fibre / matrice pouvait être influencée et ainsi proposer une solution de modification de surface permettant de diminuer ou de contrer les effets inhibiteurs identifiés et quantifiés. Ensuite, l’objectif doit être atteint par la formulation et la mise au point à l’échelle laboratoire et pré-industrielle de solutions d’ensimage de fibres de carbone afin de permettre l’amélioration de la qualité de l’interface fibre / matrice par la création d’une interphase chimique et en particulier par la création d’une chimie covalente. Nous avons mis au point deux familles de formulations d’ensimage dont une s’est avérée compatible avec les procédures industrielles de traitement d’ensimage sur fibre de carbone. Finalement, la mise en émulsion à base aqueuse de ces formulations a permis d’améliorer le niveau d’industrialisation de la solution de modification de surface et la réalisation de matériaux démonstrateurs a démontré l’amélioration des performancesPolymerization under high energy radiation is a promising alternative to autoclave processing for manufacturing high-performance composite materials. Electron beam can initiate free radical polymerization processes of acrylate-based matrix. However, the comparison with state-of-the-art thermally cured composites reveals the lower transverse mechanical properties of radiation-cured composites. The aim of this project was to improve the transverse mechanical properties of these radiation-cured composites by a surface modification of carbon fiber. We have investigated several points related to these issues, and particularly we have inquired about the influence of the chemistry present at the surface of the carbon fiber on the polymerization step initiated under irradiation curing. We tried to have a better understand on their influence on the polymerization and on the curing process based on radiation-induced free radical chemistry. Then, the next step deals with the formulation of a surface modification treatment applied by sizing in order to improve the interface quality with the creation of an interphase and even better a covalent link between the fiber and the matrix. We worked on the compatibility of this formulation with the industrial process and we propose aqueous and non-aqueous-based emulsion processes to apply the surface treatment. Finally, demonstrator materials were manufactured and the mechanical properties in the fiber transverse direction were measured. The obtained results illustrate the efficiency of our surface modification solution on the mechanical performance of acrylate-based radiation cured composites
23
CHEN, WEi-LIANG, e 陳維良. "Studies of UV-Radiation Curing Acrylate Resins". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/33394366156658709525.
Testo completoAbstract (sommario):
碩士東海大學
化學工程學系
94
As a rule, polymers start to polymerize by thermal heating; however, UV curable resins make use of the suitable wave band in UV instead of heating to cure the resins from liquid state to solid state. The advantage of using UV is due to a rapid reaction and a short period in process. UV curable resins represent the value in practice just as the resins must be completely cured in a short time. This research utilized acrylate resins, DR-1 and T5-A, which are cured by the UV-A wave band in UV. In consequence, the result shows that DR-1 is better reacted with a shorter period. In addition, we also chose glass, silver, gold, silicon, and aluminum foil as a substrate, and we found that acrylate resins can be cured by aluminum foil and glass in a shorter time. Oxygen has a great impact on curing resins. In the existence of oxygen, it needs to take a long time for the whole process. Therefore, adding nitrogen during UV irradiating can contribute to reduce the amount of oxygen and take less time for curing resins.
24
Zilic, Elvis, University of Western Sydney, College of Health and Science e School of Natural Sciences. "Radiation curing and grafting of charge transfer complexes". 2008. http://handle.uws.edu.au:8081/1959.7/19385.
Testo completoAbstract (sommario):
Charge transfer (CT) complexes have been used in a number of radiation polymerisation processes including grafting and curing. The complexes studied include donor (D) monomers like vinyl ethers and vinyl acetate (VA) with acceptor (A) monomers such as maleic anhydride (MA). Both UV and EB have been utilised as radiation sources. The complexes are directly grafted to these substrates in the presence of radiation. The complexes yield novel copolymers when radiation cured with concurrent grafting improving the properties of the finished product. The term cure grafting has been proposed for this concurrent grafting process. Studies in basic photografting work to complement the cure grafting have been proposed. The role of solvent in grafting is discussed, particularly the effect of aromatics in photografting to naturally occurring trunk polymers like wool and cellulose. The effect of the double bond molar ratio (DBMR) of the DA components in grafting is examined. The ultraviolet (UV) conditions for gel formation during photografting, hence the importance of homopolymer yields in these processes is reported. A plausible mechanism to explain the results from this photografting work is proposed. The significance of these photografting studies in the related field of curing, especially in UV and ionising radiation (EB) systems, is discussed. EB curing and cure grafting of charge transfer (CT) monomer complexes is investigated. The EB results are compared with UV curing and cure grafting of the same complexes. The work has been extended to include EB/UV curing and cure grafting of thiolene systems. The significance of these results in the potential commercial application of these complexes is discussed. Variables affecting the UV/EB curing and cure grafting of thiolenes on cellulose have been studied. These include effect of varying the type of olefin, increasing the functionality of the thiol, use of acrylate monomers and oligomers in hybrid systems, altering the surface structure of the cellulose and finally the role of air in these processes particularly with EB. Photopolymerisation of the thiol-enes in bulk has also been investigated. The thesis content is based on the published work of 14 research papers over the course of the project.Doctor of Philosophy (PhD)
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Luo, Tzyy-Jye, e 羅子傑. "Reactive Blending of PU with Organometallic Compounds by UV- Radiation Curing". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/04203109547489375944.
Testo completoAbstract (sommario):
碩士淡江大學
化學學系
86
Metallic ion coordinated PU can be formulated by an ion exchange of carboxylic group containing PU with metallic salt. Furthermore,organic/inorganic hybrids are obtained from UV- radiation curing of UV-curable PU system with zinc salt of acrylate containing borate ester (BZN) or acrylate containing borate ester (BHA) in various ratios, respectively.BHA is prepared from boric acid with 2-hydroxyethyl methacrylate(HEMA); BZN is prepared from acrylate containing boric acid (BHA-2)with zinc chloride. BHA-2 is obtained from boric acid with HEMA in1/2 ratio. The UV-curable PU system is synthesized from the additionof HEMA into NCO-terminated PU prepolymer. The UV-PU curing systemwith BZN or with BHA is irradiated with UV light from a medium pressure mercury lamp light source. The resulted UV-cured PU organic/inorganic hybrids are evaluated by TGA/FT- IR,DMA, Cone Calorimeter.
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Nwabuzor, Augustine Ogom Okoli Okenwa. "Development of the RIDFT process incorporation of ultraviolet light curing process /". 2004. http://etd.lib.fsu.edu/theses/available/etd-04202004-035547.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Florida State University, 2004.Advisor: Dr. Okenwa Okoli, Florida State University, College of Engineering, Dept. of Industrial & Manufacturing Engineering. Title and description from dissertation home page (viewed 6/16/04). Includes bibliographical references.
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MacPherson, Meoghan Elizabeth. "Photo-Curing Through Single Apertures: The Phenomenon and Its Influence On Polymerization". Thesis, 2013. http://hdl.handle.net/1805/3900.
Testo completoAbstract (sommario):
Indiana University-Purdue University Indianapolis (IUPUI)Reduction of the polymerization shrinkage stress inherent of dimethacrylate-based resin composites has been a work in progress since the phenomenon was first described by Dr. Rafael L. Bowen in 1967. Contemporary efforts to modify the composites or the curing protocols for polymerization have proven a challenging task with controversial results. Influenced by existing mathematical models relating exposure, curing time and depth of cure of resin composites, a novel method for the reduction of polymerization shrinkage stress is proposed. By polymerizing through a single aperture mask, a dental light curing unit is transformed from a planar light source to a point light source, and a fully cured, three-dimensional “bullet” shaped curing front is predicted for the cured resin below. So long as the edges of the bullet do not touch the cavity walls or floor, the shrinkage stress of the bullet is not transferred. Follow-up with an unmasked curing unit then fully polymerizes the restoration. By reducing the volume of uncured composite in contact with the cavity walls and floor, shrinkage stress of the restoration is also reduced. The objective of the present study was to demonstrate this curing phenomenon with a model resin composite using masks with aperture diameters of 0.5, 0.4, and 0.25 mm and curing times of 10, 20, 30, and 40 seconds. The resulting curing front was evaluated quantitatively and qualitatively. From this, mathematical models of the curing front were derived. Selected combinations of aperture mask and curing time were then investigated to evaluate the influence of this phenomenon on the degree of conversion, Knoop hardness, and polymerization shrinkage stress of the same model resin composite. Group differences were analyzed using a one-way ANOVA at 5% significance.
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VOTRUBOVÁ, Jitka. "Proč nezemřela paní Curieová na akutní nemoc z ozáření?" Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-364554.
Testo completoAbstract (sommario):
This thesis deals with the scientific achievements of the inspirational scientist Marie Curie Sklodowska as well as with the issue of acute iradiation sickness. Two goals were set in the work. The first objective was to map the life and scientific work of Mrs. Curie. The second objective was to describe the causes and consequences of acute illness from radiation. At the beginning the theoretical part describes the life of Marie Curie Sklodowska. Her difficult beginnings at the University of Paris and her great achievements- discovering the elements of polonium and radium. Further, the work deals with acute radiation sickness together with basics of radiobiology. In the practical part, I tried to find an answer to this question. Why Mrs. Curie did not die from acute radiation sickness? I have gained a lot of information by studying literature, professional articles and internet resources. Most of the facts were obtained from foreign professional journals because there are not many sources in the Czech language. Thanks to this information, I could deal with this person more detailed. At the same time, in the case of toxic polonium-210, an estimated fatal dose for adults was calculated. In addition, calculations were made of how much Marie Curie Sklodowska would have to isolate and incorporate in order to die for the consequences of acute radiation sickness. For better clarity, the results are summarized in the tables. Safety precautions and health problems associated with work with radioactive elements would not be neglected. Marie Curie Sklodowska probably was not able to create a clean polonium, and therefore probably did not even accept this direct contact, which would be able to cause her death.