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1
Apolonio, Fabianni MagalhÃes. "Stability of adhesive interface different adhesives applied to dentin". Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5181.
Testo completoAbstract (sommario):
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoThere is a general consensus that resin-dentin bonds created by contemporary hydrophilic dentin adhesives deteriorate over time. One way to predict how resin-dentin interface would behave over time is aging the specimens in vitro by immersion in different solutions. The objective of this study was to evaluate the effect of immersion in NaOCl solution on the bond interface created by different adhesive systems. For this, it was used 28 human third molars that had superficial dentin exposed and composite build-ups were built on its surface using one of those adhesives, etch-and-rinse: Scothbond Multi-purpose and Single Bond, or self-etch: Clearfil SE and Adper SE. Specimens were cut into nontrimming dentin-composite beams to microtensile testing. After a period of 24 h in distilled water, sticks from each tooth were divided equally into two groups: control or aged in 10% NaOCl for 1 h. Beams were pulled until failure at crosshead speed of 1 mm/min and bond strength was calculated. Fractured sticks were analyzed and classified in: mixed fracture, cohesive in dentin and cohesive in composite; and expressed in percentage. Data from ÂTBS test were statistically analyzed using Kruskal-Wallis and Games-Howell tests. For comparison between control and aging groups was used the Mann-Whitney test (α=0.05). Two specimens from each adhesive were used to investigate the effect of NaOCl on the interfacial morphological characteristics. For that, specimens were cut in only one direction, dentin-resin discs were fixed in a glass-holder and ground with SiC papers under running water. Slices were treated by Massonâs trichrome acid staining technique to evidence collagen exposed zones and analyzed by optical microscopy. ÂTBS results showed that NaOCl solution significantly reduced bond strength comparing with the control groups for all adhesives tested. Scothbond MP (control: 39,95Â12,72; aged: 26,45Â9,90 MPa) showed the highest values and Adper SE (control: 13,21Â3,15; aged 4,95Â2,49) the lowest in both control and aging groups. Clearfil SE (control : 27,02Â6,84; aged: 16,17Â3,79) and Single Bond (control : 26,66Â8,35; aged: 11,77Â4,28) showed no difference in control groups, but after aging, Clearfil SE showed better results. Microscopic images analysis showed that NaOCl acts efficiently on degradation of collagen fibrils for all adhesive systems. Conclusion: Aging in 10% NaOCl solution reduces bond strength and modifies the interfacial morphological characteristics of the adhesive systems tested.
Hà um consenso geral de que a uniÃo resina-dentina criada pelos adesivos dentinÃrios hidrofÃlicos contemporÃneos se deterioram com o tempo. Uma maneira de prever o comportamento da interface adesiva ao longo do tempo à atravÃs do envelhecimento in vitro por imersÃo em diferentes soluÃÃes. O objetivo deste trabalho foi avaliar o efeito da imersÃo em soluÃÃo de NaOCl na interface de uniÃo criada por diferentes sistemas adesivos. Para isso, foram usados 28 terceiros molares humanos que tiveram a dentina coronÃria exposta e um platà de resina composta confeccionado sobre sua superfÃcie apÃs a aplicaÃÃo de um dos seguintes sistemas adesivos, condicionamento total: Scothbond Multi-uso e Single Bond, ou autocondicionantes: Clearfil SE e Adper SE. Os espÃcimes foram cortados pela tÃcnica nontrimming de obtenÃÃo de palitos para o teste de microtraÃÃo. ApÃs um perÃodo de 24 horas em Ãgua destilada, os palitos de cada dente foram igualmente divididos em dois grupos: controle ou envelhecido em soluÃÃo de NaOCl a 10% por 1 hora. Os espÃcimes foram tracionados atà a ruptura da uniÃo a uma velocidade de 1 mm/min e sua forÃa de uniÃo mensurada. Os palitos fraturados foram analisados e classificados em: fratura mista, coesiva em dentina e coesiva em compÃsito, e os valores expressos em porcentagem. Os dados da resistÃncia de uniÃo foram estatisticamente analisados usando os testes Kruskal-Wallis e Games-Howell. Para comparaÃÃo entre os grupos controle e envelhecido foi usado o teste de Mann-Whitney (α=0.05). Dois espÃcimes de cada adesivo foram usados para investigar o efeito do NaOCl nas caracterÃsticas morfolÃgicas da interface de uniÃo. Para isso, espÃcimes foram cortados ao longo eixo em apenas uma direÃÃo e os discos de dentina-resina foram fixados em lÃmina de vidro e desgastados com lixas de SiC sob refrigeraÃÃo com Ãgua. As lÃminas foram tratadas pela tÃcnica de coloraÃÃo Ãcida de Masson para evidenciar as zonas de colÃgeno exposto e observadas atravÃs de microscopia Ãptica. Os resultados do teste de microtraÃÃo mostraram que a soluÃÃo de NaOCl reduziu significativamente a forÃa de uniÃo em comparaÃÃo aos grupos controle para todos os adesivos testados. Scothbond MU (controle: 39,95Â12,72; envelhecido: 26,45Â9,90 MPa) mostrou os maiores valores de uniÃo e Adper SE (controle: 13,21Â3,15; envelhecido 4,95Â2,49) os menores valores, tanto para o grupo controle quanto envelhecido. Clearfil SE (controle: 27,02Â6,84; envelhecido: 16,17Â3,79) e Single Bond (controle: 26,66Â8,35; envelhecido: 11,77Â4,28) nÃo mostraram diferenÃa estatÃstica nos grupos controle, mas apÃs envelhecimento, Clearfil SE mostrou melhores resultados. A anÃlise das imagens microscÃpicas mostrou que o NaOCl agiu efetivamente na degradaÃÃo das fibras de colÃgeno para todos os sistemas adesivos testados. ConclusÃo: O envelhecimento dos espÃcimes em soluÃÃo de NaOCl a 10% reduziu a resistÃncia de uniÃo e modificou as caracterÃsticas morfolÃgicas da interface adesiva para os sistemas adesivos testados.
2
Su, Ning. "Durability and fatique performance of structural adhesives and adhesive joints". Thesis, University of Dundee, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240601.
Testo completo
3
Risan, Jared. "Method for Compliance Controlled Adhesive Switching and Magnetically Controlled Switchable Adhesives". Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26990.
Testo completoAbstract (sommario):
Adhesives are used in a variety of ways and are so common that they are easily overlooked. Adhesive hooks, tapes, glues, and switchable climbing mechanisms used by insects and lizards are clear examples of how adhesives are beneficial to society and nature. The development of novel switchable adhesives is a research area that is largely incomplete. In fact, very few switchable adhesives exist on the market today; hence their development would tremendously impact the adhesive industry. This thesis studies a mechanism for stiffness controlled switchable adhesion by utilizing a magnetically switchable device. The influence of nanopowder reinforcement on the compliance of polymeric-metallic composite switchable adhesives is investigated. Highly compliant composites are switched by magnetic and mechanical clamping leading to changes in compliance and adhesion. Material characterization is done with lap-shear testing while effects of reinforcement and clamping methods are studied. Ultimately, magnetic switching is consistent with a simple mechanical model.
4
Ren, Dakai. "Moisture-Cure Polyurethane Wood Adhesives: Wood/Adhesive Interactions and Weather Durability". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/29866.
Testo completoAbstract (sommario):
This project addresses two main subjects of moisture-cure polyurethane (PUR) wood adhesives: wood/PUR interactions and structure-property behavior emphasizing on weather durability. For these purposes, one simplified model PUR (MPUR) and three more commercially significant PURs (CPURs) with different hard segment contents were prepared. Separately, an early side project involved the synthesis of a 13C and 15N double-labeled polymeric methylenebis(phenylisocyanate) (pMDI) resin; this was used for the solid-state NMR characterization of isocyanate cure chemistry in wood bondline.
MPUR and a CPUR were employed to investigate whether wood/adhesive interactions influence PUR properties. Wood interactions significantly altered PUR hard/soft domain size distribution (atomic force microscopy, AFM), thermal transition temperatures (dynamic mechanical analyses, DMA), and urethane/urea hydrogen bonds (Fourier transform infrared spectroscopy, FTIR).
The effects of hard segment content on properties of PUR prepolymers, and cured PURs (films and wood composites) were studied. Hard segment content largely influenced the PURs’ molecular weights, viscosity, penetration, thermal transitions, and hard segment hydrogen bonds, but only slightly altered the dry (unweathered) bondline toughness.
Three accelerated weathering procedures were developed to evaluate CPUR bondline weather durability through mode-I fracture testing. Both hard segment content and weathering conditions were found to significantly influence the bondline weather durability. Among these weathering procedures, only one (VPSS) was able to effectively distinguish weather durability of PUR adhesives, and therefore it was selected for detailed structure-weather durability studies. PUR weather durability was found to correlate with its moisture sensitivity and hard segment softening temperature; both were provided by water-submersion DMA. Much attention was directed to the investigation of weather-induced PUR molecular changes. FTIR studies provided evidences of post-cure, hydrolytic degradation, and variation of urethane/urea hydrogen bonds. DMA presented weathering effects on PUR thermal properties. Special efforts have been made to correlate these analytical results with PUR weather durability.
A 13C and 15N double-labeled pMDI resin was synthesized and used for solid-state NMR characterization of isocyanate cure chemistry in wood bondline, particularly to detect the evidence of urethane formation. Rotational echo double resonance (REDOR) NMR clearly revealed the formation of urethane linkages, but largely overestimated their content.Ph. D.
5
Su, Bin. "Electrical, thermomechanical and reliability modeling of electrically conductive adhesives". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/10425.
Testo completoAbstract (sommario):
The first part of the dissertation focuses on understanding and modeling the conduction mechanism of conductive adhesives. The contact resistance is measured between silver rods with different coating materials, and the relationship between tunnel resistivity and contact pressure is obtained based on the experimental results. Three dimensional microstructure models and resistor networks are built to simulate electrical conduction in conductive adhesives. The bulk resistivity of conductive adhesives is calculated from the computer-simulated model. The effects of the geometric properties of filler particles, such as size, shape and distribution, on electrical conductivity are studied by the method of factorial design.
The second part of the dissertation evaluates the reliability and investigates the failure mechanism of conductive adhesives subjected to fatigue loading, moisture conditioning and drop impacts. In fatigue tests it is found that electrical conduction failure occurs prior to mechanical failure. The experimental data show that electrical fatigue life can be described well by the power law equation. The electrical failure of conductive adhesives in fatigue is due to the impaired epoxy-silver interfacial adhesion. Moisture uptake in conductive adhesives is measured after moisture conditioning and moisture recovery. The fatigue life of conductive adhesives is significantly shortened after moisture conditioning and moisture recovery. The moisture accelerates the debonding of silver flakes from epoxy resin, which results in a reduced fatigue life. Drop tests are performed on test vehicles with conductive adhesive joints. The electrical conduction failure happens at the same time as joint breakage. The drop failure life is found to be correlated with the strain energy caused by the drop impact, and a power law life model is proposed for drop tests. The fracture is found to be interfacial between the conductive adhesive joints and components/substrates.
This research provides a comprehensive understanding of the conduction mechanism of conductive adhesives. The computer-simulated modeling approach presents a useful design tool for the conductive adhesive industry. The reliability tests and proposed failure mechanisms are helpful to prevent failure of conductive adhesives in electronic packages. Moreover, the fatigue and impact life models provide tools in product design and failure prediction of conductive adhesives.
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Kon, Haruhiko. "Characterization of adhesively bonded joints using bulk adhesive properties". Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-01242009-063346/.
Testo completo
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Soldado, Cañadas Piedad. "Propiedades físico-químicas, adaptación interfacial, biocompatibilidad y citotoxicidad de algunos cementos endodóncicos". Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663909.
Testo completoAbstract (sommario):
OBJETIVOS: Evaluar las propiedades físico-químicas y adaptación interfacial de los siguientes cementos endodóncicos: Endo-CPM Sealer, Activ GP Sealer, Sealepex y AH Plus. Cuantificar in vivo la respuesta de los tejidos apicales y periapicales de dientes de perro con vitalidad pulpar después de la obturación del conducto radicular con RealSeal XT y Sealapex Xpress. Estudiar la citotoxicidad in vitro, en cultivos celulares de RealSeal XT y Sealapex Xpress. Considerar la biocompatibilidad in vivo, en tejido subcutáneo de ratones, de RealSeal XT y Sealapex Xpress. MATERIAL Y MÉTODOS: Para evaluar las propiedades físico- químicas y la adaptación interfacial se realizaron los siguientes análisis: radiopacidad, variación de pH y solubilidad usando muestras de cada material y microscopía electrónica de barrido en conductos de incisivos bovinos obturados para evaluar la adaptación interfacial. Los datos se analizaron mediante pruebas paramétricas y no paramétricas (α=0,05). Para evaluar la respuesta apical y periapical de Sealapex Xpress y RealSeal XT se utilizaron 38 conductos radiculares de premolares de perro con pulpa vital. Posteriormente, se hizo un análisis histopatológico e inmunohistoquímico de los tejidos. Los datos se analizaron mediante la prueba U no paramétrica de Mann-Whitney (a=0,05). La citotoxicidad se evaluó observando la viabilidad celular con ensayo MTT (one-way ANOVA), prueba de azul de tripano (Mann- Whitney) y apoptosis celular tras el contacto con Sealapex Xpress y RealSeal XT. Para el estudio subcutáneo, se implantaron tubos de polietileno rellenos de Sealapex Xpress o RealSeal XT en 70 ratones BALB/c. Se realizó un estudio descriptivo del tejido peritubular y se evaluaron la proliferación y el edema angioblástico (prueba exacta de Fisher), además de medir el espesor (µm) de tejido granulomatoso reaccionario y recuento de neutrófilos (Kruskal-Wallis y Dunn's post test; Mann-Whitney) (α=0,05). RESULTADOS: La radiopacidad de todos los cementos endodóncicos evaluados estaban de acuerdo con los requisitos de ANSI / ADA. Endo-CPM Sealer presentó los valores más bajos de radiopacidad y AH Plus fue el cemento más radiopaco (p=0,0001). A excepción de Activ GP, que mostró valor de pH ácido, todos los demás cementos tuvieron una naturaleza química básica y liberaron iones hidroxilo. Con respecto a la solubilidad, todos los materiales cumplieron con las recomendaciones ANSI / ADA, sin diferencias estadísticamente significativas entre los cementos endodóncicos (p=0,0834). AH Plus presentó la mejor adaptación a las paredes del conducto en el tercio medio (p=0,0023) y apical (p=0,0012), mientras que los cementos Activ GP y Endo-CPM Sealer tuvieron una adaptación pobre a las paredes del conducto. Se observó un sellado biológico completo en el 50% y 22,7% de las muestras de los grupos Sealapex Xpress / gutapercha y RealSeal XT / Resilon, respectivamente. Se observó sellado biológico parcial en el 25% y 54,6% y ausencia de sellado en el 25% y 22,7% de las muestras de los grupos Sealepex Xpress / gutapercha y RealSeal XT / Resilon, respectivamente. La viabilidad celular mostró un efecto dosis- dependiente. En cuanto a la proliferación angioblástica y el edema, se observaron diferencias entre los cementos a los 7 y a los 63 días (p<0,05). Ambos cementos endodóncicos estimularon respuestas tisulares favorables. CONCLUSIONES: Todos los cementos endodóncicos, a excepción de Activ GP, fueron alcalinos y todos cumplieron con los requisitos ANSI / ADA de radiopacidad y solubilidad. La adaptación interfacial a las paredes del conducto radicular bovino del AH Plus fue superior a los demás. Sealapex Xpress y RealSeal XT mostraron biocompatibilidad tisular in vivo y permitieron el sellado del foramen apical mediante la deposición de tejido mineralizado. Tanto Sealapex Xpress como RealSeal XT mostraron un efecto tóxico dosis-dependiente. El cemento Sealapex Xpress fue menos citotóxico y más biocompatible que RealSeal XT.OBJECTIVES: to evaluate the physicochemical properties and interfacial adaptation to canal walls of Endo- CPM Sealer, Sealapex, Activ GP and AH Plus sealer and evaluate the response of apical and periapical tissues of dogs’ teeth with pulp vitality after root canal filling with the endodontic sealers Sealapex Xpress and RealSeal XT and the in vitro cytotoxicity and in vivo biocompatibility of this two sealers on the subcutaneous connective tissue of mice. METHODOLOGY: The following analyses were performed: radiopacity, pH variation and solubility using samples of each material and scanning electron microscopy of root-filled bovine incisors to evaluate the interfacial adaptation. Data were analyzed by the parametric and nonparametric tests (α=0,05). Thirty-eight root canals with vital pulp from dogs’ premolars were used. After instrumentation, the canals were filled with Sealapex Xpress and gutta-percha or Real Seal XT and Resilon cones. The teeth with surrounding tissues were subjected to histotechnical processing. Hematoxylin-eosin– stained sections were examined by conventional light microscopy for a quantitative histopathologic analysis, according to a scoring system. The subsequent sections were evaluated by immunohistochemistry for identification of mineralization markers. Data were analyzed by nonparametric Mann-Whitney U test (a = 0,05). The cytotoxicity was assessed by cell viability using the MTT assay (one-way ANOVA), trypan blue test (Mann-Whitney) and cell apoptosis by flow cytometer. For the subcutaneous study, polyethylene tubes filled with the sealers were implanted in 70 BALB/c mice. Angioblastic proliferation and edema (Fisher’s exact test) were evaluated, besides thickness measurement (µm) of the reactionary granulomatous tissue and neutrophil counts (Kruskal-Wallis and Dunn’s post test; Mann-Whitney) (α = 0,05). RESULTS: All materials were in accordance with the ANSI/ADA requirements for radiopacity. Endo-CPM Sealer presented the lowest radiopacity values and AH Plus was the most radiopaque sealer (p=0,0001). Except for ActiV GP, which was acidic, all other sealers had basic chemical nature and released hydroxyl ions. Regarding solubility, all materials met the ANSI/ADA recommendations, with no statistically significant difference between the sealers (p=0,0834). AH Plus presented the best adaptation to canal walls in the middle (p=0,0023) and apical (p=0,0012) thirds, while the sealers Activ GP and Endo-CPM Sealer had poor adaptation to the canal walls. Complete biological sealing was observed in 50% and 22,7% of the specimens of groups SX/GP and RS/R, respectively. Partial biological sealing was observed in 25% and 54,6% and absence of sealing in 25% and 22,7% of the specimens of groups SX/GP and RS/R, respectively. There were no significant differences (P > ,05) between the groups for the scores attributed to the histopathologic parameters. Positive staining for osteopontin, alkaline phosphatase, and RUNX2 was observed in both groups, especially in the periodontal ligament. MTT assay, trypan blue and analysis of apoptotic cells showed a dose-dependent direct effect: the more diluted the sealer, the less cytotoxic. Regarding the angioblastic proliferation and edema, difference between the sealers at 7 and 63 days occurred (p < 0,05). Both endodontic sealers initially promoted perimaterial tissue reaction as a foreign body granuloma and thus stimulated favorable tissue responses. CONCLUSIONS: All sealers, except for ActiV GP, were alkaline and all of them fulfilled the ANSI/ADA requirements for radiopacity and solubility. Regarding the interfacial adaptation, AH Plus was superior to the others considering the adaptation to the bovine root canal walls. Sealapex Xpress and RealSeal XT feature tissue compatibility in vivo and allow for sealing of apical opening by deposition of mineralized tissue. Both sealers showed a dose-dependent effect and promoted satisfactory subcutaneous tissue response; the sealer Sealapex Xpress was less cytotoxic and more biocompatible than RealSeal XT.
8
Xu, Botao. "Fracture mechanisms and failure criteria of adhesive joints and toughened epoxy adhesives". Thesis, Queen Mary, University of London, 2010. http://qmro.qmul.ac.uk/xmlui/handle/123456789/371.
Testo completoAbstract (sommario):
Adhesive bonded applications are used widely in industry because of significant advantages such as uniform stress distribution, and the ability to join different materials. However most epoxy structural adhesives are brittle at room temperature and it is required to improve their toughness. The objective of this work was to understand the fracture of adhesive joints, failure criteria and rubber toughening mechanisms via a series of experiments and FEA modelling. Double lap joints (DLJ) bonded by commercial AV119 adhesive were studied. It was found that local strain and failure path were controlled by adhesive thickness. In order to model adhesive joints accurately and efficiently, systematic fracture tests were implemented to determine the fracture criteria. Mode-I, mode-II and mixed mode fracture energy release rates were obtained by Fixed Arm Peel, 4-point End Notched Flexure (ENF) and Mixed Mode Bending (MMB) tests. Numerical analysis was applied to determine the parameters of the Drucker-Prager material model and Cohesive Zone Model (CZM). The 3D FEA results showed good agreement with experimental results of DLJ and MMB. FEA results successfully demonstrated bonding strength, stress and strain distribution and plastic deformation; and further details were found using sub models. The rubber toughening mechanism was studied by modelling different face-centred micromodels. The stress distributions ahead of the crack tip in global DLJ models were extracted and used as the loading condition for the micromodels, so that a relationship between macromodel and micromodel has been established. It is found that Von Mises and hydrostatic stress play very important roles in the toughening mechanisms and also predicted that rubber particles with multi-layer structure have more potential to toughen epoxy resin than simple rubber particles.
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Deplace, Fanny. "Waterborne nanostructured adhesives". Paris 6, 2008. http://www.theses.fr/2008PA066035.
Testo completoAbstract (sommario):
Nous avons étudié les propriétés d’adhésifs préparés à partir de particules de latex nanostructurées. Une méthodologie basée sur deux critères rhéologiques a été proposée pour optimiser les performances adhésives. Elle nous a permis d’identifier des stratégies applicables dans le cas particulier de PSA préparés à partir de particules de latex ayant une morphologie cœur-écorce. Une stratégie intéressante est l’activation d’une réaction de réticulation interparticule pendant le séchage du latex. Nous avons montré l’effet remarquable de cette réaction de réticulation sur les propriétés en grandes déformations. Ces propriétés sont assez bien décrites par un modèle non-linéaire combinant le modèle de Maxwell sur convecté et le modèle de Gent. Les meilleurs résultats d’adhésion sont obtenus pour des PSA préparés à partir de particules de latex ayant une fine écorce réticulée et un cœur mou et caractérisés par un net ramollissement à déformations intermédiaires suivi d’un rhéodurcissement. Dans un registre plus industriel, des performances adhésives prometteuses ont été obtenues avec des PSA préparés à partir de latex tackifiés in situ synthétisés par polymérisation en miniémulsion.
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Manterola, Najera Julen. "Development of advanced methods to characterise the fracture behaviour of flexible bonded joints". Doctoral thesis, Universitat de Girona, 2020. http://hdl.handle.net/10803/672807.
Testo completoAbstract (sommario):
Advanced joining technologies such as bonded joints play an important role to develop more efficient and durable structures. The present Thesis gives a step forward and proposes different solutions to characterise the fracture behaviour of flexible bonded joints for laboratory and industrial activities. Unlike in laboratory practices, thick and tough adhesives are applied in industrial activities. Moreover, bonded joints have multiple geometries and non-visible cracks may appear, while bonded joints are subjected to service environment. Four different subjects have been addressed to bring both fields closer: the effect of interface dimensions on the fracture behaviour, the effect of sustained loads on durability studies, the development of a new durability test for bonded joints, and the application of acoustic emissions technique for crack growth monitoring. Experimental and numerical works converge in different methods showing a great potential to be used in future projects with an industrial application.Las tecnologías de unión avanzadas como las uniones adhesivas tienen un papel relevante en el desarrollo de estructuras eficientes y duraderas. La presente Tesis propone diferentes soluciones para caracterizar el comportamiento a fractura de uniones adhesivas flexibles para actividades de laboratorio e industriales. A diferencia del laboratorio, los adhesivos que se aplican en la industria son tenaces y de gran espesor. Además, tienen múltiples geometrías, están expuestas a condiciones de servicio y se agrietan tras procesos no visibles. Se han abordado los siguientes temas para acercar la actividad de laboratorio al industrial: el efecto de la geometría de la interfaz en el comportamiento a fractura, el efecto de cargas sostenidas en estudios de durabilidad, el desarrollo de un nuevo ensayo de durabilidad y la aplicación de emisiones acústicas como técnica no destructiva para monitorizar grietas. El trabajo experimental y numérico desarrolla diferentes métodos con potencial para utilizarse en proyectos industriales.
Programa de Doctorat en Tecnologia
11
Puthenparambil, Abhilash. "Effect of bonding pressure on reliability of anisotropic conductive adhesives [sic] joints in a silicon-to-flex-substrate interconnction". Diss., Online access via UMI:, 2006.
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Dietrich, Jan [Verfasser]. "Functional adhesives and functionally graded adhesives in fiber metal laminates / Jan Dietrich". Paderborn : Universitätsbibliothek, 2020. http://d-nb.info/1217325867/34.
Testo completo
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Nasiri, Anahita. "The Use of Lignin in Pressure Sensitive Adhesives and Starch-Based Adhesives". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39853.
Testo completoAbstract (sommario):
After cellulose, lignin is the second most abundant natural polymer in the world. It has multiple functional groups, providing great potential for polymer production. In this project, we explored the use of this renewable and valuable resource in two different adhesive applications to displace petroleum-based additives, thereby providing a more sustainable and “green” product. In this regard, two types of lignin, water-soluble (Amalin LPH) and non-water-soluble lignin (Amalin HPH) provided by the British Columbia Research Institute (BCRI) were used.
In the first case, lignin was added to a pressure-sensitive adhesive (PSA) formulation via in-situ seeded semi-batch emulsion polymerization. It was seen that lignin does not readily take part in the polymerization reaction; rather, its presence results in reaction inhibition. Therefore, Amalin LPH lignin was modified via acrylation to overcome this issue. In another modification approach, maleic anhydride was used to produce maleated Amalin HPH lignin. Both the acrylated and maleated lignins were used in butyl acrylate/methyl methacrylate emulsion copolymerizations to produce PSA films. A series of controlled experiments with different lignin loadings was conducted. Adhesive properties of the PSA films were measured and compared with the corresponding acrylic base case formulation. The incorporation of lignin in the PSA formulation was a “green” solution to conventional PSA production and led to a simultaneous increase in tack and shear strength. Further characterization of the latex films via transmission electron microscopy (TEM) showed that lignin was successfully incorporated into the polymer particles. It also showed that the use of maleated lignin at a higher concentration led to a core-shell morphology.
In the second application, unmodified Amalin LPH lignin was used to create a starch-based adhesive through the Stein-Hall process, a two-step process involving a “carrier” portion and a “slurry” portion. Several formulations with lignin loadings up to 35 wt% distributed in varying ratios in the carrier and slurry portions were prepared. It was shown that the addition of lignin to the starch-based adhesive formulation increases the water-resistance of the adhesive. Therefore, lignin addition is a solution for a common issue in starch-based adhesives, their lack of water-resistance due to the high affinity of starch toward water. Lignin incorporation solely in the slurry portion significantly increased the strength of the glued joints in a paper board adhesive test.
The use of lignin as a renewable replacement of petroleum-based components in two different adhesive formulations was demonstrated successfully. This research strongly suggests that lignin can be used as a high value-added property modifier in adhesive applications.
14
Tanguy, Francois. "Debonding mechanisms of soft adhesives : toward adhesives with a gradient in viscoelasticity". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-01021169.
Testo completoAbstract (sommario):
During the debonding of a soft adhesive (as are Pressure Sensitive Adhesives or PSA), complex mechanisms enter in competition at the interface and in the bulk of the adhesive film. In order to optimize these adhesives, it is crucial to understand the transitions between the different debonding modes. We studied these transitions using model materials and carried out a quantitative analysis of debonding experiments with a new image analysis method. We also modeled the mechanical behavior of our materials under uniaxial deformation by using a 2-modes Phan-Thien and Tanner (PTT) viscoelastic model. These studies showed the strong heterogeneity of the debonding mechanisms where process at the interface and in the bulk are in competition. To obtain more efficient PSA, we optimized their properties by introducing a gradient in the viscoelastic properties of the film along their thickness. Bi-layer optimized systems showed interesting properties on surfaces with high or low adhesion. Finally, adhesives with a continuous gradient were realized and characterized by the diffusion of a cross-linker in a polymer film followed by an activation of the cross-linking reaction at a given time
15
Tanguy, Francois. "Debonding mechanisms of soft adhesives : toward adhesives with a gradient in viscoelasticity". Electronic Thesis or Diss., Paris 6, 2014. http://www.theses.fr/2014PA066079.
Testo completoAbstract (sommario):
Lors du décollement d'un adhésif mou (tels que les adhésifs sensibles à la pression, dits PSA), des mécanismes complexes entrent en jeu à l'interface et dans l'épaisseur du film d'adhésif. Afin d¿optimiser ces adhésifs, il convient de maîtriser les transitions entre les différents modes de décollement. Nous avons étudié ces transitons grâce à des matériaux modèles. Nous avons réalisé une analyse quantitative d'expériences de décollement, en nous appuyant notamment sur une nouvelle technique d'analyse d'image. Nous avons également modélisé le comportement mécanique de nos matériaux en traction uniaxiale grâce à un modèle viscoélastique de Phan-Thien et Tanner (PTT) à deux modes. Ces études ont montré la forte hétérogénéité des mécanismes de décollement où des processus à l'interface et dans l'épaisseur de l'adhésif sont en compétition. Pour obtenir des PSA plus efficaces, nous avons donc optimisé leurs propriétés en introduisant un gradient dans les propriétés viscoélastiques du film selon leur épaisseur. Des systèmes bi-couches optimisés montrent d¿intéressantes propriétés, sur surface de forte ou de faible adhésion. Enfin, des adhésifs à gradient continu ont été réalisés et caractérisés via la diffusion d'un réticulant dans un film de polymère puis activation à un instant précis de la réaction de réticulationDuring the debonding of a soft adhesive (as are Pressure Sensitive Adhesives or PSA), complex mechanisms enter in competition at the interface and in the bulk of the adhesive film. In order to optimize these adhesives, it is crucial to understand the transitions between the different debonding modes. We studied these transitions using model materials and carried out a quantitative analysis of debonding experiments with a new image analysis method. We also modeled the mechanical behavior of our materials under uniaxial deformation by using a 2-modes Phan-Thien and Tanner (PTT) viscoelastic model. These studies showed the strong heterogeneity of the debonding mechanisms where process at the interface and in the bulk are in competition. To obtain more efficient PSA, we optimized their properties by introducing a gradient in the viscoelastic properties of the film along their thickness. Bi-layer optimized systems showed interesting properties on surfaces with high or low adhesion. Finally, adhesives with a continuous gradient were realized and characterized by the diffusion of a cross-linker in a polymer film followed by an activation of the cross-linking reaction at a given time
16
Tilley, Eve Rochelle. "Structural polymers for adhesives". Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417728.
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17
Su, Bin. "Electrical, thermomechanical and reliability modeling of electrically conductive adhesives". Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-12192005-124641/.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Qu, Jianmin, Committee Chair ; Baldwin, Daniel, Committee Member ; Wong, C. P., Committee Member ; Sitaraman, Suresh, Committee Member ; Jacob, Karl, Committee Member.
18
Leijonmarck, Simon. "Electrically Induced Debonding of Adhesives". Licentiate thesis, KTH, Tillämpad elektrokemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-27742.
Testo completoAbstract (sommario):
Electrically induced adhesive debonding is a process where an adhesive can be debonded at command with help of an applied voltage. To make this process function, the adhesive is bonded between two metal substrates. In this study an epoxy adhesive is adhered between two aluminium foils forming a laminate structure. The adhesive is made ionically conductive by an addition of an ionic liquid before the curing. This arrangement forms an electrochemical cell, where the metal substrates act as the electrodes while the ionically conductive adhesive acts as the electrolyte. When a voltage is applied over the laminate, a current passes due to electrochemical reactions at the electrode interfaces and ionic transport in the adhesive. This type of material can potentially be used in a wide range of applications. This includes making adhesive joints in automotives to both reduce the total weight but also to simplify the disassembly after end-of-life, enabling an inexpensive recycling process. Another potenital use for debondable adhesives is within consumer packaging. Here it could be possible to pack and transport goods using less packaging material as well as making the handling easier. The aim of this study was to increase the understanding about the processes leading to debonding. This knowledge is important in the development of new types of debonding adhesives. In this study, the commercial laminate Sinuate® was used as a model system. The experiments were focused on the electrochemical behavior and were performed mainly using galvanostatic polarization and electrochemical impedance spectroscopy. Information about the chemistry of debonding was collected with techniques such as scanning electron microscopy (SEM), mass spectrometry (MS) and Raman spectroscopy. The debonding did always take place at the anodic interface, separating the adhesive and the anode aluminium foil. It was found that the total cell resistance increased drastically during polarization, and that essentially all of this increase originated within the anodic half of the laminate. Examining the resistance behavior with EIS, it was found that the increase in total resistance was reversible. The anodic electrochemical reaction during polarization was determined to consist mainly of an oxidation of aluminium, while the major reaction at the cathodic interface was reduction of water into hydrogen. The debonding process, which took place at the anodic interface, could be related to reaction products formed in the polarization process. These products grew out from the anodic aluminium surface into the adhesive. A debonding mechanism is proposed where these products induce an increase in the adhesive volume, causing stresses at the interface which ultimately result in debonding.Elektriskt framkallad delaminering är en process som gör att en limfog kan fås att släppa på kommando med hjälp av en pålagd elektrisk spänning. För att processen ska fungera måste limmet vara bundet till två metallytor. I den här studien används ett epoxylim, bundet mellan två folier av aluminium, vilket bildar en laminatstruktur. Limmet gjordes jonledande genom en tillsats av en jonvätska innan härdningen. Detta laminat bildar en elektrokemisk cell, där metallytorna agerar som elektroder och limmet som elektrolyt. När en elektrisk spänning läggs över laminatet, uppstår en elektrisk ström till följd av elektrokemiska reaktioner vid elektrodytorna och jontransport i limmet. Dessa material skulle kunna användas inom ett brett spektrum av användningsområden. Exempel på detta är användandet av limmade fogar i fordon, vilket skulle både minska fordonens vikt och underlätta demonteringen efter livscykelns slut. En förenklad demontering skulle resultera i en billig återvinningsprocess. Andra exempel på användningsområden för elektriskt släppbara limmer är konsumentförpackningar. Inom detta område skulle varor kunna packas med mindre mängd förpackningsmaterial och hanteringen under transport och uppackning skulle kunna förenklas. Målet med det här arbetet var att öka förståelsen kring processerna som leder till delaminering. Dessa kunskaper är viktiga för utvecklande av nya sorter av elektriskt släppande limmer. Det kommersiella laminatet Sinuate® användes som ett modellsystem. Experimenten fokuserades kring elektrokemin och utfördes främst med galvanostatisk polarisering och elektrokemisk impedansspektroskopi (EIS). Information om släpprocessens kemi inhämtades med tekniker som svepelektronmikroskopi (SEM), masspektrometri (MS) och Raman-spektroskopi. Det upptäcktes att delamineringen alltid skedde i det anodiska gränsskiktet, på så sätt att aluminiumfolien och limytan separerades. Polarisationsprocessen ledde till en drastisk ökning av den totala cellresistansen och större delen av denna härrörde sig från den anodiska delen av laminatet. Denna ökning i resistans fanns vara reversibel genom att använda EIS. Den elektrokemiska reaktionen vid anoden bestod till största delen av en oxidation av aluminium, medan den katodiska reaktionen bestod av en reduktion av vatten till vätgas. Processerna som ledde till släpp i det anodiska gränsskitet kunde härledas till SEM-resultaten, där reaktionsprodukter observerades. Dessa produkter växte ut från aluminiumytan och in i limmet. En släppmekanism föreslås, där de bildade produkterna orsakar en volymsökning i limmet, vilket leder till spänningar i gränsskiktet som i sin tur gör att limmet släpper.
QC 20101222
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Khosravi, Sara. "Protein-Based Adhesives for Particleboards". Licentiate thesis, KTH, Ytbehandlingsteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33750.
Testo completoAbstract (sommario):
The main objective of this study was to elucidate the possibilities to use wheat gluten (WG) as a binder for particleboards, as well as soy protein isolate (SPI). The focus was on the effect of the adhesive formulation and the processing conditions, while the press parameters were kept constant. Some aspects of the dispersion and the preparation of the dispersions that were investigated are: the time (1, 3 or 5h) to prepare the dispersion, the temperature (room temperature, 50 or 80°C) during the preparation of the dispersions and the effect of storing (1, 2.5 or 4 days) the dispersions. Furthermore, the utilization of green particles versus dried particles was examined. The concentration (12, 16, 20 or 24%) of WG dispersion and the process for applying it to the particles was studied. Two application methods were evaluated, in application method 1 (appl. 1) all the dispersion was added to the particles in one step before the particles were dried. When application method 2 (appl. 2) was employed the dispersion was added in two steps, some of the dispersion was added before the drying and some after the drying. The considered board properties were internal bond (IB), thickness swelling (TS) and water absorption (ABS). The results show that in the case of SPI dispersion the temperature seems to not be of significant importance and it appears as if longer time to prepare the dispersion is beneficial. On the other hand for WG dispersion it looks as if a lower temperature is preferable for the preparation of the dispersion and that the time to prepare the dispersion is of no importance. Furthermore, storing the dispersions for more than one day before it was used as an adhesive for particleboards (PB) resulted in poorer boards. According to this study it is beneficial to use dried particles instead of green particles. Additionally, the results show that the interaction between the concentration of WG dispersion and how it is applied is a significant factor, considering the IB value. However, in general the two step process (appl. 2) is preferable.Huvudsyftet med den här studien var att undersöka möjligheterna att använda vetegluten (WG) som bindemedel för spånskivor, även sojaproteinisolat (SPI) har undersökts. Fokus låg på effekten av formuleringen av bindemedlet och processbetingelserna, medan pressparametrarna hålls konstanta. En del parametrar som studerades med avseende på tillverkning av dispersionerna var: tiden (1, 3 eller 5 h) att bereda dem, vid vilken temperatur (rumstemperatur, 50 eller 80°C) de preparerades och effekten av att lagra (1, 2,5 eller 4 dagar) dispersionerna. Vidare, undersöktes användning av råspån kontra torkat spån. Koncentrationen (12, 16, 20 eller 24 %) för WG-dispersionerna och processen för belimning med dessa dispersioner utvärderades. Två applikationsmetoder testades, i applikationsmetod 1 tillsattes hela mängden dispersion i ett steg till spånet innan det torkades. I applikationsmetod 2 tillsattes dispersionen i två steg en del tillsattes innan torkning och resten tillsattes efter torkning. Skivegenskaperna som utvärderades var, tvärdrag (IB), svällning (TS) och absorption (ABS). Resultaten visade att det kan vara fördelaktigt att tillreda SPI-dispersioner under en längre tid och det verkar inte som att temperaturen är en viktig parameter. Däremot förefaller det som att lägre temperatur är gynnsamt när en WG-dispersion ska blandas och att tiden inte är av signifikant betydelse. Vidare, förefaller det som att lagring längre än en dag av dispersionerna har en negativ effekt på deras förmåga som bindemedel för spånskivor. Enligt den här studien är det fördelaktigt med avseende på skivegenskaper att använda torkat spån istället för råspån. Resultaten visar att samverkan mellan koncentration och applikationsmetod kan vara en signifikant faktor, med avseende på IB-värdena. Dock verkar det överlag som att tvåstegsbelimningen är fördelaktig.
QC 20110518
20
Knox, Esther M. "Marine applications for structural adhesives". Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241876.
Testo completo
21
Tredwell, S. "The durability of phenolic adhesives". Thesis, De Montfort University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371422.
Testo completo
22
Fior, Valerie F. "A beam test for adhesives". Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43969.
Testo completoAbstract (sommario):
The strength of materials solution for a new bonded cantilever beam test specimen to determine adhesive shear properties is reviewed and discussed. A parametric analysis for the adhesive shear stress and for the end deflection reveals the specimen dimensions required for reliable bonded adhesive shear properties determination. Recommendations are provided for conducting reproducible tests. A pure and quasi-uniform shear test for stiff adhesives is proposed.
Analytical solutions are compared with Finite Element solutions from VISTA and NOVA for the stresses in the adhesive. It appears that the assumption of pure shear is nearly valid even for very stiff and/or very thick adhesives. In order to increase the end point deformations for stiff adhesives, a modified specimen is proposed. Three-dimensional effects through the thickness of the adhesive layer are studied with the program ABAQUS.
Experiments were performed using the two methods derived from theory and good correlation between theory and experiment were obtained with some restrictions. For both methods, experimental results underlined the need for defining proper specimen geometry prior to testing. Simple numerical codes are proposed to facilitate this purpose.Master of Science
23
Bott, Richard H. "Characterization of modified polyimide adhesives". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53914.
Testo completoAbstract (sommario):
An addition polyisoimide prepolymer was modified through the incorporation of metal particles. The response of this metal/polymer composite to mechanical vibrations and the passage of electric current was measured. Model aluminum conductor bar joints containing this material were assembled and exposed to elevated temperatures for extended periods of time while the electrical properties of the composites were monitored. In the most favorable systems, no thermal degradation of the electrical properties was observed. Dynamic mechanical behavior of the metal/polymer composites indicated good adhesion between particles and the matrix and also a broadening of the glass transition region as well as a post Tg dispersion in the temperature spectrum. The adhesive properties of these metal/polymer composites to aluminum were studied and found to be influenced by the loading level of the metal in the composite.
Chemical reactions occurring during the cure of a neat resin sample of the polyisoimide prepolymer were monitored using infrared spectrometry and differential scanning calorimetry. Both the crosslinking and isomerization reactions were found to be apparently first order with the isomerization having a lower activation energy than the crosslinking. Linear, high molecular weight, thermoplastic polyimides and poly(imide-siloxane) homo- and copolymers prepared by bulk and solution thermal imidization were investigated as structural adhesives for titanium. The solution thermal imidization procedure was found to result in favorable adhesive characteristics while the presence of siloxane segments in the polymer backbone improved the resistance of stressed specimens to moisture. Aluminum-sec-butoxide used as a primer was also found to improve the moisture durability of bonds prepared with these materials.Ph. D.
24
Rusanen, Outi. "Adhesives in micromechanical sensor packaging /". Espoo : Technical research centre of Finland, 2000. http://catalogue.bnf.fr/ark:/12148/cb409218404.
Testo completo
25
Schmitz, John F. "Enzyme modified soy flour adhesives". [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3369888.
Testo completo
26
Doody, Paul David. "The rheology and strength of hot melt adhesives". Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/aee7101d-7aef-41a0-a6a1-32d9877f92d1/1.
Testo completoAbstract (sommario):
Various properties of the components and adhesives were modelled. The compatibility of the components were successfully incorporated into an extended Fox equation to predict the glass transition temperature. The peel strength of the adhesive was modelled in terms of the rheological properties of elastic moduli and loss tangent values at different temperatures. A second model based upon the value of the loss tangent at room temperature was also broadly successful but deviations from predicted behaviour were observed which were attributable to failure of the adhesive joints by a mode not included in the model. The modulus of the adhesive was modelled on the basis of an extended mixture rule in which the extent of compatibility was identified by a parameter n. The value of n varied as a function of adhesive composition and temperature, indicating that the behaviour of the adhesives changed subtly as the compatibility of the phases changed. The value of the parameter could not be directly related to the morphology of the adhesive phases. Fourteen commercially available poly(ethylene-co-vinyl acetate) (EVA) copolymer samples were selected in which there was a systematic change in the melt index, amount of vinyl acetate, and degree of crystallinity. Various hot melt adhesives were made using these copolymers and a standard amount of wax and resin. The materials were examined using differential scanning calorimetry (DSC), oscillatory rheometry (both controlled strain and controlled stress), and transient (creep) rheometry. The adhesives were also investigated using a variety of industrial tests which included peel adhesion and tensile testing at four different rates, open and setting time, shear and peel stress resistance at elevated temperatures, and viscosity determination over a wide range of temperatures. Detailed thermal analysis and characterisation have provided a range of accurate and systematic data on all of the materials and in particular showed that the components of the adhesive did not merely act as a mechanical mixture but had a distinct compatibility. The controlled stress technique was found to more discriminatory than the controlled strain, due to the more precisely controlled heating and cooling of the sample during loading and evaluation. Other key differences between the techniques are attributable to the different thermal histories imposed upon the semi-crystalline adhesive components. Detailed analysis of the complex rheological curves showed several key factors. One of the most important was the modulus crossover temperature Tx which was shown to correlate well with the softening point of the adhesive, its open time, and the heat resistance under shear as determined by the shear adhesion failure temperature (SAFT). It was possible to construct a linear relationship between Tx and SAFT which allowed prediction of this key adhesive parameter. There was no significant relationship established between the softening point of an adhesive and its heat resistance, open time, or critical thermal characteristics, and the use of the softening point as a useful indicator of adhesive performance is contested. The open time was shown to be clearly influenced by the properties of the copolymer. The relationship between open time and melt index is complex and two competing mechanisms are thought responsible. These are the inability to fully wet the substrate for high molecular weights and resistance to complete substrate penetration by capillary effects for adhesives formulated with low molecular weight polymers. Both of these effects cause a reduction in open time. The cloud points of the adhesives were independent of the molecular weight but strongly affected by composition. Degree of crystallinity was also an influence at higher molecular weights. Cloud point correlated slightly with the onset of crystallisation as determined by DSC however differences are extremely small and the method was not deemed robust enough for widespread industrial application. Various properties of the components and adhesives were modelled. The compatibility of the components were successfully incorporated into an extended Fox equation to predict the glass transition temperature. The peel strength of the adhesive was modelled in terms of the rheological properties of elastic moduli and loss tangent values at different temperatures. A second model based upon the value of the loss tangent at room temperature was also broadly successful but deviations from predicted behaviour were observed which were attributable to failure of the adhesive joints by a mode not included in the model. The modulus of the adhesive was modelled on the basis of an extended mixture rule in which the extent of compatibility was identified by a parameter n. The value of n varied as a function of adhesive composition and temperature, indicating that the behaviour of the adhesives changed subtly as the compatibility of the phases changed. The value of the parameter could not be directly related to the morphology of the adhesive phases.
27
Glavas, Lidija. "Starch and Protein based Wood Adhesives". Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31486.
Testo completoAbstract (sommario):
Different native starches, modified starches and plant proteins were evaluated as wood adhesives. They were combined with different synthetic polymers in order to achieve improved adhesive properties. The study was divided into two parts: development of starch based adhesive formulations and evaluation of an existing protein based adhesive. Eight different starches and two different plant proteins were used in the first part. Starch 1 and starch 2 as well as protein 1 and protein 2 were some of the used materials. These materials were dispersed in synthetic polymers such as poly (vinyl acetate) (PVAc), styrene-butadiene rubber (SBR), poly (vinyl alcohol) (PVA), poly (acrylic acid) (PAA) and poly (ethylene-co-vinyl acetate) (EVA). Five different cross-linking agents were also tested. In the second part of the study, protein 2 was used as a renewable material. It was dispersed in dispersing media 2 and filler 1 was used. In an effort to increase the amount of renewable material in the adhesive composition, six different renewable fillers were examined. Lower pressing temperatures as well as lower amounts of cross-linking agent 1 were evaluated in order to observe their influence on the adhesive properties of the protein based adhesive. All formulations were characterized by measurement of viscosity, solid content and pH. The adhesive properties of some of the formulations in both parts of the study were characterized according to SS-EN 204:2001 and EN 14257 (WATT 91). The best results, of the starch based formulations, were obtained when starch 1 and protein 2 were dispersed in dispersing media 2 or dispersing media 7. These formulations in combination with cross-linking agents were classified as D2 and passed the criteria for heat resistance (WATT 91). However, the results were comparable with the reference sample. It was possible to replace filler 1, totally or partly, in the protein based adhesive with renewable fillers. Protein based adhesive formulations with filler 2 and filler 4, amongst others, showed improvement of the adhesive properties. These formulations passed D3 and D4 – wet criteria and almost passed D4 – boiling criteria. The amount of renewable material in the protein based adhesive was increased from ~32 % to ~56 % in the formulations that obtained the best adhesive properties. The amount of non-petrochemical material was ~67 % in all new formulations as well as in the reference sample. By decreasing the pressing temperature from 110 °C to 90 °C or by decreasing the amount of cross-linking agent 1 from 15 % to 5 %, a protein based system that passes D3 criteria can be obtained.
28
Karlsson, Patrik. "Determination of viscoelastic properties of adhesives". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35521.
Testo completoAbstract (sommario):
A research project at Linnaeus University focuses on optimizing theadhesives joints between wood and glass, with the aim of obtain stiffcomponents that can act as a load and stabilizing elements and still betransparent. But there is, however, still a lack of knowledge regarding theadhesive materials which need to be further investigated. This thesis focused on testing six different adhesives in relaxation and todetermine the viscosity (η) and modulus of elastic (MOE, E). Viscosity andMOE are then used in combination in a standard linear solid model (SLS)describing the viscoelasticity mathematically. Figures and tables are used topresent the results and the evaluation. The so determined parameters can beused in e.g. finite element models for the design of load bearing timber glasscomposites.
29
Graves, Colin G. "Electrically conductive adhesives based on polythiophene". Thesis, Anglia Ruskin University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410803.
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30
Luckyram, Jeenarainsingh. "Fatigue and fracture of structural adhesives". Thesis, University of Dundee, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240139.
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31
Zhang, Hong Sheng. "Polymerised acrylates for use in adhesives". Thesis, City University London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306054.
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Jain, Dharamdeep. "Humidity Driven Performance of Biological Adhesives". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510053266807976.
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33
Mylonakis, Andreas Wei Yen. ""Biodegradable polymer adhesives, hybrids and anomaterials" /". Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2911.
Testo completo
34
Ellison, Matthew M. "Metal/polymer interactions in polyimide adhesives". Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-08282003-155323/.
Testo completo
35
Browne, Gloria Joyce 1951. "Volatile organic emissions from carpet adhesives". Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/291538.
Testo completoAbstract (sommario):
In this study volatile organic compounds (VOCs) emitted during carpet installations employing water-based adhesives were characterized. The potential impacts of 4 adhesives on indoor air quality were evaluated. Headspace sampling and analysis by gas chromatography/mass spectrometry were used to qualitate VOC emissions. Adhesives and carpet/adhesive composite samples were prepared for quantitative analysis of VOC emissions by gas chromatography with flame ionization detection. Volatiles were concentrated using a monitoring device and collected on charcoal adsorption tubes. Sampling intervals ranged from 30 minutes to 21 days. The adhesives emitted primarily aromatic, alicyclic and aliphatic compounds as toluene, m-xylene, 1,2-dimethylcyclohexane, alpha-pinene, 2-methylheptane, octane, nonane, decane and undecane. Emission profiles depended on performance characteristics and manufacturer. A carpet boundary layer slowed VOC decay by acting as a sink. Potential overexposure within 24 hours to specific and total VOCs was indicated for one of the adhesives. This study suggests that water-based carpet adhesives are a potential source of indoor air pollutants.
36
Özmen, Nilgül. "Lignin based adhesives for particleboard production". Thesis, Bangor University, 2000. https://research.bangor.ac.uk/portal/en/theses/lignin-based-adhesives-for-particleboard-production(38b5f43f-c055-4156-b03c-492391d66d59).html.
Testo completoAbstract (sommario):
The purpose of this study was to utilise lignin as a partial substitute for phenol in PF resins. To achieve this, initially brown rot lignin was produced by a bioconversion technique. During the course of the study, it became clear that the production of brown rot lignin had a limited success. Since brown rot lignin could not be obtained in sufficient quantity and purity by a bioconversion method, other alternative lignin production methods, as well as commercially available lignin, were chosen; namely production of lignin from black liquor and Alcell® (organosolv) lignin. Before performing production of resin formulations, the lignin sources were characterised in terms of reactivity and physical properties of lignins. Both lignins had a similar reactivity, but organosolv lignin was found to be more pure, with a low ash content. Since isolation of lignin from black liquor in laboratory conditions is more complex and requires more time, it was decided to use organosolv lignin for subsequent production of lignin-based reSIns. The lignin was introduced to the resin in two different ways. The first method was the replacing of a certain percentage of phenol with lignin (as supplied) directly into resins. In the second method, lignin was modified prior to resin manufacture by phenolation. Different degrees of phenol substitution (from 5% to 60%) were tried for the production of lignin-based resins. Bond qualities of lignin-phenol-formaldehyde (LPF) , phenolated-ligninformaldehyde, commercial phenol-formaldehyde (PF _com) and laboratory made phenol-formaldehyde (PF _made) resins were assessed by using an Automatic Bonding Evaluation System (ABES), prior to production of particleboards, in order to eliminate some of the poor quality resins. The effect of press temperature and time on bond strength appeared to be highly significant, as the lignin substitution levels increased. Up to 30% phenol substitution was achieved without sacrificing bond strength. The bond strength values of phenolated-lignin-formaldehyde resins were similar to commercial phenol-formaldehyde and laboratory made phenolformaldehyde resins, but better than the LPF resins. It was apparent that resins containing a high level of lignin substitution gave the poorest bond strength values. From these results, some of the resins were eliminated, prior to particleboard production. In order to evaluate the quality of lignin-based resins, particleboards were produced and mechanical and physical tests performed. Effect of press platen temperature (140°C, 160°C, 180°C) and press cycle time (5 min, 8 min, IS min) on the mechanical properties of particleboard, produced by using lignin-based resins, were investigated. It was found that particleboards bonded with up to 30% lignin content resins gave similar mechanical and physical properties to commercial phenolformaldehyde resin, as long as a sufficient heating regime and time were applied.
37
Butkus, Lawrence M. "Environmental durability of adhesively bonded joints". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/19008.
Testo completo
38
Siu, Frederick Y. K. "Studies of microwaves applications for adhesive, weld joint and NDT technique". Swinburne Research Bank, 2007. http://hdl.handle.net/1959.3/36854.
Testo completoAbstract (sommario):
Thesis (MEng) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2007.A thesis submitted for fulfillment of the requirement for the degree of Master of Engineering, Industrial Research Institute, Swinburne University of Technology - 2007. Typescript. Includes bibliographical references (p. 168-193).
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Miletic, Vesna. "Micro-Raman spectroscopic studies on the adhesive-dentine interface and the degree of conversion of dental adhesives". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4415.
Testo completoAbstract (sommario):
A series of studies on monomer to polymer conversion in adhesive systems was undertaken using micro-Raman spectroscopy. A database of micro-Raman spectra was compiled for identification of tooth tissues and materials. The degree of conversion was assessed as a function of time and light source. Linear and two-dimensional micro- Raman characterisations of the adhesive-dentine and resin-based composite-adhesivedentine interfaces were performed. The degree of monomer to polymer conversion of adhesive systems was correlated with the amount of eluted monomers obtained by highperformance liquid chromatography. The degree of conversion varied significantly depending on adhesive chemical composition, curing time and light source. It was impossible to specify one curing time applicable to all adhesive systems, due to differences in conversion kinetics. In general, conventional halogen light-curing units at twenty seconds curing time produced similar or higher degree of conversion in adhesive systems compared to high-power LED units at ten seconds. Significantly higher monomer conversion was found in the adhesive layer compared to the hybrid layer in both etch-and-rinse and self-etch systems. Etch-and-rinse adhesive systems formed thicker hybrid layers compared to self-etch systems. Micro-Raman spectroscopy gave a more precise indication of dentine demineralisation and adhesive penetration than scanning electron microscopy and indicated that the hybrid layer is a gradual transitional zone between the adhesive layer and un-affected dentine. The absolute amount and weight percent of eluted monomers varied in all tested adhesive systems. In most adhesive systems, more than 90% of eluted monomers were detected within the first one hour of immersion. Overall, no correlation was found between the degree of conversion and the amount of eluted monomers.
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Paris, Jesse Loren. "Carboxymethylcellulose Acetate Butyrate Water-Dispersions as Renewable Wood Adhesives". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/34644.
Testo completoAbstract (sommario):
Two commercial carboxymethylcellulose acetate butyrate (CMCAB) polymers, high and low molecular weight (MW) forms, were analyzed in this study. High-solids water-borne dispersions of these polymers were studied as renewable wood adhesives. Neat polymer analyses revealed that the apart from MW, the CMCAB systems had different acid values, and that the high MW system was compromised with gel particle contaminants. Formulation of the polymer into water-dispersions was optimized for this study, and proved the â direct methodâ , in which all formulation components were mixed at once in a sealed vessel, was the most efficient preparation technique. Applying this method, 4 high-solids water dispersions were prepared and evaluated with viscometry, differential scanning calorimetry, dynamic mechanical analysis, light and fluorescence microscopy, and mode I fracture testing.
Thermal analyses showed that the polymer glass transition temperature significantly increased when bonded to wood. CMCAB dispersions produced fairly brittle adhesive-joints; however, it is believed toughness can likely be improved with further formulation optimization. Lastly, dispersion viscosity, film formation, adhesive penetration and joint-performance were all dependent on the formulation solvents, and moreover, these properties appeared to correlate with each other.Master of Science
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Degrandi, Elise. "LATEX HYBRIDES URETHANE/ACRYLIQUE POUR APPLICATIONS ADHESIVES". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00465348.
Testo completoAbstract (sommario):
Cette thèse a pour objet l'étude de films adhésifs obtenus par le séchage de particules de latex hybrides uréthane/acrylique. Ces latex ont été préparés par polymérisation en miniémulsion pour assurer une incorporation homogène du polyuréthane dans chaque particule. L'étude de la morphologie des particules et des films a montré que le greffage du polyuréthane sur le réseau acrylique est essentiel pour éviter une séparation de phase à l'échelle du film, néfaste pour les propriétés macroscopiques. Les propriétés mécaniques de ces films hybrides sont contrôlés par deux paramètres indépendants : La fraction massique de polyuréthane affecte la viscoélasticité linéaire de ces films adhésifs alors que le taux de greffage du polyuréthane modifie le comportement en grandes déformations en modifiant la maille du réseau réticulé. En modifiant le taux de greffage, il est possible de maintenir un niveau d'adhérence satisfaisant par rapport à un film d'acrylique pur tout en augmentant la cohésion dans le matériau et donc la résistance au cisaillement. Cette méthode de synthèse par miniémulsion peut être transposée vers un processus plus industriel et l'effet des paramètres moléculaires reste globalement le même. L'effet du greffage apparaît toujours comme essentiel sur la déformabilité maximale des films adhésifs mais les conditions de synthèse augmentent fortement la densité de points de réticulation dans le matériau, ce qui diminue leur adhérence mais augmente leur résistance au cisaillement. Nous avons enfin mis au point un test de fluage en traction, permettant d'appréhender la résistance mécanique des adhésifs dans le temps.
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Bihari, Kathleen L. "Analysis of Thermal Conductivity in Composite Adhesives". NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010808-130536.
Testo completoAbstract (sommario):
BIHARI, KATHLEEN LOUISE. Analysis of Thermal Conductivity in Composite Adhesives (Under the direction of H. Thomas Banks). Thermally conductive composite adhesives are desirable in many industrial applications, including computers, microelectronics, machinery and appliances. These composite adhesives are formed when a filler particle of high conductivity is added to a base adhesive. Typically, adhesives are poor thermal conductors. Experimentally only small improvements in the thermal properties of the composite adhesives over the base adhesives have been observed. A thorough understanding of heat transfer through a composite adhesive would aid in the design of a thermally conductive composite adhesive that has the desired thermal properties.In this work, we study design methodologies for thermally conductive composite adhesives. We present a three dimensional model for heat transfer through a composite adhesive based on its composition and on the experimental method for measuring its thermal properties. For proof of concept, we reduce our model to a two dimensional model. We present numerical solutions to our two dimensional model based on a composite silicone and investigate the effect of the particle geometry on the heat flow through this composite. We also present homogenization theory as a tool for computing the ``effective thermal conductivity" of a composite material.We prove existence, uniqueness and continuous dependence theorems for our two dimensional model. We formulate a parameter estimation problem for the two dimensional model and present numerical results. We first estimate the thermal conductivity parameters as constants, and then use a probability based approach to estimate the parameters as realizations of random variables. A theoretical framework for the probability based approach is outlined.Based on the results of the parameter estimation problem, we are led to formally derive sensitivity equations for our system. We investigate the sensitivity of our composite silicone with respect to the thermal conductivity of both the base silicone polymer and the filler particles. Numerical results of this investigation are also presented.
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Lu, Daoqiang. "Fundamental understanding of electrically conductive adhesives (ECA's)". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19911.
Testo completo
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Naldrett, Michael James. "Cement and other adhesives in the barnacle". Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306213.
Testo completo
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Miles, A. L. "The geometric modification of high temperature adhesives". Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311365.
Testo completo
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Zheng, Jun. "Studies of PF Resole / Isocyanate Hybrid Adhesives". Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/25960.
Testo completoAbstract (sommario):
Phenol-formaldehyde (PF) resole and polymeric diphenylmethane diisocyanate (PMDI) are two commonly used exterior thermosetting adhesives in the wood-based composites industry. There is an interest in combining these two adhesives in order to benefit from their positive attributes while also neutralizing some of the negative ones. Although this novel adhesive system has been reportedly utilized in some limited cases, a fundamental understanding is lacking. This research serves this purpose by investigating some of the important aspects of this novel adhesive system.
The adhesive rheological and viscometric properties were investigated with an advanced rheometer. The resole/PMDI blends exhibited non-Newtonian flow behavior. The blend viscosity and stability were dependent on the blend ratio, mixing rate and time. The adhesive penetration into wood was found to be dependent on the blend ratio and correlated with the blend viscosity. By using dynamic mechanical analysis, the blend cure speed was found to increase with the PMDI content. Mode I fracture testing of resole/PMDI hybrid adhesive bonded wood specimens indicated the dependence of bondline fracture energy on the blend ratio. The 75/25 PF/PMDI blend exhibited a high fracture energy with a fast cure speed and processable viscosity. Exposure to water-boil weathering severely deteriorated the fracture energies of the hybrid adhesive bondlines.
More detailed chemistry and morphological studies were performed with cross-polarization nuclear magnetic resonance and 13C, 15N-doubly labeled PMDI. A spectral decomposition method was used to obtain information regarding chemical species concentration and relaxation behavior of the contributing components within the major nitrogen resonance. Different urethane concentrations were present in the cured blend bondlines. Water-boil weathering and thermal treatment at elevated temperatures (e.g. > 200°C) caused reduced urethane concentrations in the bondline. Solid-state relaxation parameters revealed a heterogeneous structure in the non-weathered blends. Water boil weathering caused a more uniform relaxation behavior in the blend bondline.
By conducting this research, more fundamental information regarding the PF/PMDI hybrid adhesives will become available. This information will aid in the evaluation of, and improve the potential use of PF/PMDI hybrid adhesives for wood-based composites.Ph. D.
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Riedlinger, Darren Andrew. "Characterization of PF Resol/Isocyanate Hybrid Adhesives". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31366.
Testo completoAbstract (sommario):
Water-based resol phenol formaldehyde, PF, and organic polymeric methylenebis(phenylisocyanate), pMDI, are the two primary choices for the manufacture of exterior grade wood-based composites. This work addresses simple physical blends of pMDI dispersed in PF as a possible hybrid wood adhesive. Part one of this study examined the morphology of hybrid blends prepared using commercially available PF and pMDI. It was found that the blend components rapidly reacted such that the dispersed pMDI droplets became encased in a polymeric membrane. The phase separation created during liquid/liquid blending appeared to have been preserved in the cured, solid-state. However, substantial interdiffusion and copolymerization between blend components also appeared to have occurred according to measured cure rates, dynamic mechanical analysis, and atomic force microscopy. In the second part of this study a series of PF resins was synthesized employing the so-called â split-cookâ method, and by using a range of formaldehyde/phenol and NaOH/phenol mole ratios. These neat PF resins were subjected to the following analyses: 1) steady-state flow viscometry, 2) free formaldehyde titration, 3) non-volatile solids determination, 4) size exclusion chromatography, 5) quantitative solution-state 13C nuclear magnetic resonance, NMR, 6) differential scanning calorimetry, 7) parallel-plate oscillatory cure rheology, and 8) dielectric spectroscopy. The neat PF analytical results were unremarkable with one exception; NMR revealed that the formaldehyde/phenol mole ratio in one resin substantially differed from the target mole ratio. The neat PF resins were subsequently used to prepare of series of PF/pMDI blends in a ratio of 75 parts PF solids to 25 parts pMDI solids. The resulting PF/pMDI blends were subjected to the following analyses: 1) differential scanning calorimetry, 2) parallel-plate oscillatory cure rheology, and 3) dielectric spectroscopy. Similar to what was inferred in part one of this study, both differential scanning calorimetry (DSC) and oscillation cure rheology demonstrated that cure of the PF continuous phase was substantially altered and accelerated by pMDI. However within actual wood bondlines, dielectric analysis detected little variation in cure speed between any of the formulations, both hybrid and neat PF. Furthermore, the modulated DSC curing experiments detected some latent reactivity in the hybrid system, both during initial isothermal curing and subsequent thermal scanning. The latent reactivity may suggest that a significant diffusion barrier existed between blend components, preventing complete reaction of hybrid blends even after thermal scanning up to 200 °C. Part three of this work examined the bonded wood mode-I fracture performance of hybrid resins as a function of the resol formaldehyde/phenol ratio and also the alkali content. A moderate increase in unweathered fracture toughness was observed for hybrid formulations relative to neat PF. Following accelerated weathering, the durability of the hybrid blends was promising: weathered hybrid toughness was equivalent to that of weathered neat PF. While the resol F/P ratio and alkali content both influenced hybrid fracture toughness, statistical modeling revealed interaction between these variables that complicated result interpretation: the influence of hybrid alkali content depended heavily on each formulationâ s specific F/P ratio, and vice versa.Master of Science
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Yang, Xing. "Organic Fillers in Phenol-Formaldehyde Wood Adhesives". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64999.
Testo completoAbstract (sommario):
Veneer-based structural wood composites are typically manufactured using phenol-formaldehyde resols (PF) that are formulated with wheat flour extender and organic filler. Considering that this technology is several decades old, it is surprising to learn that many aspects of the formulation have not been the subject of detailed analysis and scientific publication. The effort described here is part of a university/industry research cooperation with a focus on how the organic fillers impact the properties of the formulated adhesives and adhesive bond performance. The fillers studied in this work are derived from walnut shell (Juglans regia), alder bark (Alnus rubra), and corn cob (furfural production) residue.
Alder bark and walnut shell exhibited chemical compositions that are typical for lignocellulosic materials, whereas corn cob residue was distinctly different owing to the high pressure steam digestion used in its preparation. Also, all fillers had low surface energies with dominant dispersive effects. Surface energy of corn cob residue was a little higher than alder bark and walnut shell, which were very similar.
All fillers reduced PF surface tension with effects greatest in alder bark and walnut shell. Surface tension reductions roughly correlated to the chemical compositions of the fillers, and probably resulted from the release of surface active compounds extracted from the fillers in the alkaline PF medium.
It was shown that viscoelastic network structures formed within the adhesive formulations as a function of shear history, filler type, and filler particle size. Relative to alder bark and walnut shell, the unique behavior of corn cob residue was discussed with respect to chemical composition.
Alder bark and walnut shell exhibited similar effects with a decrease of adhesive activation energy. However, corn cob reside caused much higher adhesive activation energy.
Alder bark exhibited significant particle size effects on fracture energy and bondline thickness, but no clear size effects on penetration. Regarding corn cob residue and walnut shell, particle size effects on fracture energy were statistically significant, but magnitude of the difference was rather small. Classified corn cob residue fillers all resulted in a similar bondline thickness (statistically no difference) that was different walnut shell.Ph. D.
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Ge, Liehui. "Synthetic Gecko Adhesives and Adhesion in Geckos". University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1294161826.
Testo completo
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Blandini, Lucio. "Structural use of adhesives in glass shells". Beuren Stuttgart Grauer, 2005. http://d-nb.info/989872211/04.
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