Introduction: Adhesive technology represents a significant advancement among different treatment options of dental caries. Its advantages involve not only highly aesthetic reconstructions, but also ability to preserve hard dental tissues compared to more traditional filling materials such as amalgam, where the material retention was achieved through undercuts. A potential of adhesive technology to arrest progression of an incipient caries has triggered its wider use in dental caries management, potentiated by an ongoing development of new adhesive systems and composite materials that assure an acceptable long-term stability of adhesive reconstructions. Adhesive bonds of dental reconstructions are in the oral cavity constantly challenged by various mechanical, chemical and biological factors. One of the chemical agents with detrimental potential is peroxide bleaching gel used for teeth brightening. Currently bleaching belongs to the most frequent cosmetic dental procedures. The active ingredient of bleaching gels is hydrogen peroxide or its precursors. It is assumed that free oxygen radicals released from peroxides attack double bonds of chromophore molecules captured within the tooth tissues. Because of the high reactivity and nonspecific nature of these oxygen radicals, they may affect also dental...

La toxicité des émissions de formaldéhyde rejetées par les panneaux de particules à base de résines contenant du formaldéhyde motive la recherche de liants alternatifs notamment d’origine naturelle. Ce travail porte sur l’élaboration par thermopressage et la caractérisation physico-mécanique de panneaux de particules sans ou à faibles rejets de formaldéhyde à partir des tiges de kénaf (Hibiscus cannabinus) et de la colle d’os ou de liants végétaux riches en tannins ou en mucilage de plantes tropicales. L’utilisation de ces bioadhésifs a permis d’obtenir des panneaux de bonne résistance en flexion (370 = MOE = 3100 MPa ; 2,01 = MOR = 23 MPa). Un procédé peut être envisagé pour une production de ces panneaux utilisables comme matériaux de construction écologiques / The proven toxicity of lignocellulosic composites based on urea-formaldehyde, phenol-formaldehyde type resins by their formaldehyde emissions cause environmental health problems. A study has been carried out to enhance the development of particleboards of low density with few formaldehyde emissions manufactured with Hibiscus cannabinus core reinforcements and matrix of bone adhesive or tannin material from pod of Parkia biglobosa, stem barks of Pithecellobium dulce and foliar sheath of Sorghum caudatum or mucilaginous material from calyx of Bombax costatum and stem barks of Grewia venusta. Vegetable materials were employed in rough powders or extracts forms, or in mixture with the bone adhesive. The results obtained reveal that bone adhesive was as valuable as the urea formaldehyde resin for manufacturing particleboard with good mechanical properties (MOE: 541 MPa, MOR: 5.23, IB: 0.58 MPa). Tannin and mucilaginous rough materials gave particleboards with bending modulus of elasticity (MOE) ranging from 370 to 400 MPa, bending modulus of rupture (MOR) varying from 2.01 to 3.17 MPa and internal bond (IB) going from 0.06 to 0.28 MPa. Those plant extracts leaded to particleboards with variable mechanical properties (MOE: 484 –1100 MPa, MOR: 2.36 – 5.66 MPa and IB: 0.11 – 0.46 MPa) depending of the nature of the adhesive. Tannin based adhesive gave particleboards more valuable than mucilaginous ones. The association of the bone adhesive with the rough or the extracts of the plants material improved the mechanical characteristics of the panels

Timber-concrete composite (TCC) structures are becoming more popular in several industrial applications as an efficient method for optimizing the structural performance and the cost of construction as well as lowering the emissions of carbon dioxide. TCC floors are more sustainable than pure concrete floors and more resistant to vibrations and excessive deflections than pure wooden floors. The effectiveness of a TCC floor is dependent on the connection between the materials. The stiffness and strength of the composite element increases by having a rigid connection. An example of a rigid connection is an adhesive-bonded connection, however obtaining a connection without slip is difficult considering there will always be certain amount of slippage in the connection. In this thesis adhesive connections are investigated with two different types of adhesive, one called Sikasil SG-500 and the other Sika PS. The application of the adhesives for the test specimen differ. Since Sika PS is a more fluid glue, a different approach was necessary than for the Sikasil SG-500. Five test specimen were tested of each adhesive by performing double shear push out tests and comparing the results to a numerical model, which was performed in ABAQUS. In the numerical model, the adhesive was created as a cohesive element. Furthermore the properties of the modeled adhesive was based on the experimental results for respective adhesive. The experimental results showed that both adhesives managed the estimated shear force in the serviceability limit state and the ultimate limit state and yet remained in the elastic region. Sikasil SG-500 turned out to be more flexible while Sika PS specimen resulted in higher shear strength. The short creep tests (30 minutes of a constant load) showed that the deformation increased more for Sika PS than for Sikasil SG-500. However both adhesives had large deformations after only 30 minutes. There was also a difference in the average longitudinal shear strength, where it resulted in 1.06 MPa for Sikasil SG-500 and 2.02 MPa for Sika PS. This study indicates that Sika PS is more preferable in TCC structures than Sikasil SG-500.

Call number: LD2668 .T4 1985 L43 / Master of Science

The behaviour of spot welded joints is to be studied in shear mode by using the end notched flexure (ENF) specimen. The specimen counts on several spot welds spaced with the same gap along the entire length except for the notch. Different configurations of the test specimen spacing gap and spot diameter are to be preliminary designed in software PTC-CREO 2.0 in order to obtain accurate results. The results obtained from the software are to be compared with the experimental analysis performed by means of a servo-hydraulic testing machine. Both the virtual and the experimental results will be used to extract the stress-shear displacement relation around the first spot weld which is in contact with the notch, that is, the corresponding cohesive law. In addition, a comparison between adhesive and spot weld behaviours will be carried out by means of analytical equations in order to prove an existing equalisation between each other. Despite assuming several sources of error and after facing some problems related to the experimental work, accurate convergences between experimental and theoretical results were not accomplished in any of the three tests performed in lab. Due to the plastic deformation of the specimens in lab, the cohesive law was possible to be extracted only from the theoretical analysis, but not from the experimental one. In its place, the load-shear displacement was extracted. Some alternatives to solve this issue and to improve the performance of the tests are given at the end of this paper.

Master of Science / Department of Grain Science & Industry / Xiuzhi Susan Sun / Bio-based protein adhesives derived from renewable resources, especially soy protein are becoming more significant due to the concerns about environment and health related issues and the limit of petroleum recourses. However, the relatively poor water resistance of soy-based protein adhesives limits its wide applications. The goal of this study was to improve the water resistance performance of soy-based protein adhesives by chemical modification. The specific objectives are 1) to modify soy protein with calcium carbonate (CaCO[subscript]3) and sodium bisulfite (NaHSO[subscript]3) as the denaturing agents; 2) to investigate the effects of calcium carbonate (CaCO[subscript]3) concentrations, curing time and curing temperatures on adhesion performance of the modified soy-based protein adhesives. In this study, the co-effects of NaHSO[subscript]3 and CaCO[subscript]3 on adhesion properties of soy protein adhesives were investigated. NaHSO[subscript]3 was added to soy flour slurry at constant concentration 6g/L, while concentration of CaCO[subscript]3 was chosen in the range of 0 to 23g/L. Soy protein adhesives modified with 4g/L and 16g/L CaCO[subscript]3 were selected to characterize the adhesion performance on 3 ply yellow pine plywood using the Response Surface Method (RSM). The effects of curing temperature and curing time on the adhesion properties were also studied. The major findings are 1) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 modified soy protein adhesives (MSPA) had better adhesion performance (both dry and wet) than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA; 2) Higher temperature (170°C) resulted in higher wet shear adhesion strengths; 3) Longer hot press time had positive impact on wet adhesion shear strength; and 4) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA showed better adhesion shear strength after 2 weeks storage than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA. In general, 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA, under longer hot press time and higher temperature would lead to a better adhesion performance.

O objetivo deste trabalho foi avaliar diferentes materiais de cobertura (sistemas adesivos e selantes de superfície) quanto à alteração de cor e rugosidade quando aplicados sobre a superfície da resina composta. Noventa corpos de prova foram confeccionados em resina composta Z350 XT, A2E (3M Oral Care) com o auxílio de molde em Teflon (5x5x3mm). Após sua confecção, os corpos de prova foram imersos e mantidos em água deionizada durante 24h em estufa a 370C. Em seguida, os corpos de prova foram polidos, lavados em cuba ultrassônica e então distribuídos aleatoriamente nos grupos experimentais (n=10): 1) CTRL - somente polimento ; 2) SB - Adper SingleBond II (3M Oral Care); 3) US - Single Bond Universal (3M Oral Care); 4) CF - Clearfil SE (Kuraray); 5) APS - Ambar APS (FGM); 6) BF - Bioforty (Biodinâmica); 7) FF - Fortify (Bisco); 8) PS - PermaSeal (Ultradent); 9) GC - G CoatPlus (GC). Os corpos de prova foram avaliados quanto à alteração de cor em um Espectrofotômetro e quanto à rugosidade em um Perfilômetro óptico. Após as leituras iniciais, os corpos de prova foram imersos em vinho tinto e as medidas de ?E (alterac?a?o de cor) e Ra (rugosidade) foram analisadas nos tempos 24h, 72h e 168h. Os dados foram submetidos à análise de variância (ANOVA), testes de Tukey e teste de correlação de Pearson (p< 0,05). Não houve estabilidade de cor em nenhum dos grupos experimentais, inclusive no controle. Os selantes de superfície: BF, FF e PS e o sistema adesivo SB apresentaram a menor alteração em 24h e semelhante ao CTRL. O sistema adesivo APS apresentou a maior alteração de ?E em todos os tempos testados e diferença estatística em relação aos demais grupos (p<0,05). Em até 72h a alteração de cor ocorreu em maior intensidade, com tendência estabilizar-se em 168h para todos os grupos experimentais. Na aplicação imediata, os selantes de superfície e o sistema adesivo APS apresentaram a maior lisura superficial. Após 168h, o selante de superfície GC apresentou o menor valor de rugosidade e todos os demais materiais apresentaram-se semelhantes ao CTRL. Não houve correlação entre alteração de cor e rugosidade. / The purpose of this work was to evaluate different surface treatments (adhesive systems and surface sealants) regarding color change and roughness when applied on the surface of the composite resin. Ninety test specimens were made of composite resin Z350 XT, A2E (3M Oral Care) with the aid of Teflon mold (5x5x3mm). After the preparation of the specimens, they were immersed and kept in deionized water for 24 hours in an oven at 37°C. Then, the specimens were polished, washed in ultrasonic bath and then distributed randomly in the experimental groups, (n=10): 1) CTRL - only the polishing procedure; 2) SB - Adper SingleBond II (3M Oral Care); 3) US - Single Bond Universal (3M Oral Care); 4) CF - Clearfil SE the \"Bond\" bottle (Kuraray); 5) APS-Amber APS (FGM); 6) BF - Bioforty (Biodynamic); 7) FF - Fortify (Bisco); 8) PS - PermaSeal (Ultradent); 9) GC - G CoatPlus (GC). The specimens were analyzed regarding color alterations with a spectrophotometer and roughness changes with an optical profilometer. After the initial readings, the specimens were immersed in red wine and the measurements of ?E (color change) and Ra (roughness) were analyzed after 24h, 72h and 168h. Data were submitted to analysis of variance (ANOVA), Tukey\'s tests and Pearson correlation tests (p<0.05). Color stability was not observed in any of the analyses groups, including the control group. The surface sealants BF, FF and PS and the adhesive system SB presented the smallest alterations in 24h and similar to the CTRL. The adhesive system APS presented the highest ?E alterations in all times tested and it was statistically different from other groups (p<0.05). Within 72h the color change occurs at higher intensity, with a tendency to stabilize in 168h for all experimental groups. In the immediate application, the surface sealants and the adhesive system APS showed the highest superficial smoothness. After 168h, the surface sealant GC presented the lowest roughness value and all the other materials behaved similarly to the CTRL. There was no correlation between color and roughness changes.

A degradação do adesivo e colágeno é considerada uma das principais causas de falhas nos processos adesivos à dentina. A completa infiltração de resinas hidrofóbas facilitada pelo etanol, associada à presença de inibidores de metaloproteinases presentes na dentina, poderia construir a união ideal, resistente à hidrólise e atividades enzimáticas. Este estudo examinou os benefícios do uso combinado de clorexidina como inibidor de metaloproteinases e etanol, na durabilidade de uniões resina-dentina. Foram utilizados 48 terceiros molares hígidos para obter superfícies planas de dentina que foram condicionadas com ácido fosfórico a 32% por 15 segundos, lavadas por 30 segundos, e secas com papel absorvente. Imediatamente após, uma das seguintes soluções foi aplicada por 30 segundos: água (A); etanol (E); solução aquosa de clorexidina a 1% (CA); solução alcoólica de clorexidina a 1% (CE). O excesso foi removido com papel absorvente e um dos adesivos, All Bond 3 (AB3) ou Excite (EX), foi aplicado à superfície sob agitação por 15 segundos, seguido por um jato de ar por igual tempo, e fotoativado por 20 segundos. Uma coroa de aproximadamente 4 mm foi construída incrementalmente em resina composta e os dentes foram armazenados por 24 horas em água destilada à 370C. A seguir foram cortados em paralelogramos para o teste de microtração. Um terço dos corpos de prova foi ensaiado imediatamente e os demais permaneceram armazenados por 6 ou 15 meses. Os efeitos dos tratamentos e períodos de armazenagem foram analisados para cada adesivo. Os resultados não demonstraram interação entre os fatores para ambos os adesivos. AB3 foi significantemente afetado pela armazenagem, mas não pelos tratamentos. EX foi significantemente afetado pelo tratamento, mas não pela armazenagem. Concluiu-se que o uso de clorexidina/etanol não melhorou a estabilidade da união após 15 meses. AB3 quando tratado com A ou CA, e EX com todos os tratamentos não foram afetados pela armazenagem. / Both adhesive and collagen degradation have been regarded as major causes of resin-dentin bonds failures over time. Complete infiltration of hydrophobic resins facilitated by ethanol, and the presence of MMPs inhibitors within the hybrid layer would build the ideal interface, resistant to hydrolysis and enzymatic activities. This study examined the benefits of the adjunctive use of chlorhexidine and ethanol on the durability of resin dentin bonds. Forty-eight flat dentin surfaces were etched (32% phosphoric acid), rinsed (30s) and blot-dried with absorbent paper. The surfaces were re-wetted with either water (Water); 1% chlorhexidine diacetate in water (CHX/Water); 100% ethanol (Ethanol); and 1% chlorhexidine diacetate in ethanol (CHX/Ethanol) solutions for 30s. They were then bonded with All Bond 3 (AB3, Bisco) or Excite (EX, Ivoclar- Vivadent) using a smooth, continuous rubbing application (15s), followed by 15s gentle air dry. The adhesives were light-cured (20s) and resin build-ups constructed incrementally for the microtensile method. Bonded beams were obtained and tested after 24-hours, 6-months, and 15- months water storage at 370C. Effects of treatment and testing periods were analyzed (ANOVA, Holm-Sidak, p<0.05) for each adhesive. There were no interactions between factors for both adhesives. AB3 was significantly affected by storage, but not by treatments. Excite was significantly affected by treatments, but not by storage. Adjunctive use of ethanol/chlorhexidine did not improve bond stability after 15 months. AB3 treated either with ethanol or CHX/ethanol resulted in reduced bond strengths after 15 months. AB3 treated with water or CHX/water and all treatments for Excite were not affected by storage.

Esta pesquisa avaliou o efeito de diferentes técnicas de limpeza aplicadas na superfície de esmalte intacto, na resistência adesiva de resina composta usando sistemas adesivos self etch. Coroas dentais foram cortadas e obtidos 90 fragmentos (n=10), cujas superfícies de esmalte permaneceram em contacto com saliva humana fresca por 1 hora, recebendo a seguir de acordo com o grupo, limpeza com uma das seguintes técnicas: pasta de pedra pomes/água seguida de detergente aniônico Tergensol (PP), jato de bicarbonato de sódio (B), ou spray ar/água (C). Após limpeza, um dos sistemas adesivos foi aplicado: Clearfil SE Bond (CF), Adper Prompt (AD) ou Scotchbond Multi-Purpose (SB), realizando-se um bloco de resina composta Z250 de 4 ou 5 mm sobre o adhesivo dental. Após 24 horas de armazenagem, os corpos de prova foram cortados em maquina Labcut, originando palitos com área adesiva de aproximadamente 1 mm 2 . Cada palito foi adaptado em um dispositivo de tração, para serem realizados os testes de resistência adesiva. A análise estadística, considerando a cada palito como unidade amostral, e os tipos de fraturas apresentadas, mostrou ausência de diferença entre os sistemas adesivos usados. Entre as técnicas de limpeza testadas, valores de RMT foram superiores para a técnica de PP, não se encontrando diferenças estatisticamente significantes entre B e C. A análise ao MEV da interface esmalte/resina confirmou os resultados estatísticos encontrados e permitiu observar que a interação resina adhesiva/esmalte ocorre de maneira diferente entre os sistemas self etch e all etch. Concluiu-se que, a técnica PP constitui uma opção adequada de limpeza de superfícies de esmalte liso intacto e que a técnica de bicarbonato pode afetar a resistência adesiva destas superfícies. / This study evaluated the effect of different cleaning techniques in the adhesive bond strength of self-etching bonding systems to unground enamel after being in contact with human saliva. Ninety enamel fragments were obtained from dental crowns (n = 10) and the enamel surface of each fragment were kept in contact with fresh human saliva for 1 hour. Next, they received the cleaning treatment according to the group as follows: pumice and water paste followed by anionic detergent - Tergensol (PP), sodium bicarbonate jet (B), or air/water spray (control group - C). After cleaning procedures, one of the bonding systems was applied: Clearfil SE Bond (CF), Adper Prompt (AD), or Scothbond Multi-Purpose (SB), and a Z250 composite resin bloc with 4 or 5 mm was built above the dental adhesive. After 24 hours of storage, the specimens were sectioned to obtain sticks with cross sectional areas of approximately 1 mm². The sticks were submitted to microtensile test in an Instron testing machine. Statistical analysis of the results, considering each stick as a sample unit and the fracture kinds presented, showed no statistical significant difference in mean shear bond strength among the bonding systems used. Regarding to the cleaning techniques, shear bond strength values were superior for PP and there was no significant statistical difference between B and C. The interface enamel/dentin SEM analysis corroborated the statistical results I was concluded that PP method is appropriate for cleaning unground enamel surface after salivary contact, improving bond strength of all etch and self etch adhesive systems, and that cleaning with sodium bicarbonate jet may affect the bonding strength of these surfaces.

Para caracterizar a linha adesiva e a penetração do adesivo em de vigas de madeira lamelada colada (MLC), quatro espécies de madeira de reflorestamento Pinus sp, Schizolobium amazonicum (Paricá), Lyptus® e Tectona grandis (Teca) e quatro adesivos diferentes: (i) Purbond HB S390: adesivo à base de poliuretano; (ii) Jowapur 686.60: adesivo à base de poliuretano; (iii) Cascophen: adesivo à base de resina fenol-resorcinol e (iv) Melamina (MUF): adesivo à base de folmaldeído, foram utilizados na preparação de peças de madeira lamelada colada (MLC), seguindo instruções dos fabricantes dos adesivos. De cada viga, foram cortadas duas lâminas para analisar as características da adesão por meio de técnicas de microscopia, usando-se corpos de prova com dimensões adequadas a cada técnica utilizada. As linhas adesivas e as regiões de interfase foram submetidas à observação por microscopia óptica com luz polarizada, microscopia de fluorescência, microscopia eletrônica de varredura, microscopia confocal e microtomografia de raios X. Os adesivos Purbond HB S390 e Jowapur 686.60, apresentaram bolhas de ar na linha de cola após a cura, que podem ser relacionadas com comportamentos observados no cisalhamento das amostras, e o segundo ainda apresentou cristais e evidencias de tensão residual. Os adesivos MUF e Cascophen não apresentaram evidencias da presença de nenhum desses elementos. Os resultados das técnicas de microscopia mostraram que a penetração do adesivo resultante em cada caso, ocorreu nos vasos, no lúmen dos traqueídes e ao longo dos raios e está ligada à densidade das madeiras. As técnicas microscópicas mostraram-se complementares com informações características de cada uma delas. O tingimento das amostras facilitou a visualização das imagens na microscopia ótica, sendo útil na análise de tensão residual, formação de cristais e bolhas no adesivo, porém a técnica não permitiu a determinação de penetração de adesivo na interfase. A microscopia de fluorescência permitiu a visualização de todas as fases da linha adesiva, a profundidade da penetração grosseira e a identificação de bolhas. Porem os resultados têm pouco foco, baixa resolução e necessitam do uso de sonda fluorescente. A fluorescência confocal também permitiu identificação de todas as fases da região adesiva, profundidade de penetração grosseira e celular, com alta resolução e contraste de cores, porém gerou sombras nas regiões de irregularidade da superfície da amostra. A microscopia eletrônica de varredura permitiu a determinação precisa da espessura da linha adesiva na fase pura, a visualização do preenchimento de alguns lúmens, mas a escala de tons de cinza pode gerar dúvidas na diferenciação do adesivo e madeira. A micro CT permitiu determinar a penetração em três dimensões, com alta resolução, porém necessita de contraste adicionado ao adesivo para ensaio em madeiras de alta densidade. A partir desse estudo identificou-se a necessidade do uso das técnicas microscópicas como complemento nos estudos de ligações adesivas em MLC. Os resultados do presente trabalho indicam que as técnicas microscópicas devam passar a fazer parte das normas para testes de qualidade de MLC. / Four species of reforestation species Pinus sp, Schizolobium amazonicum (Paricá), Lyptus® e Tectona grandis (Teca) and four different adhesives (i) Purbond HB S390: poliurethane based adhesive; (ii) Jowapur 686.60: poliurethane based adhesive; (iii) Cascophen: phenol-resorcinol resin based adhesive and (iv) Melamine (MUF): formaldehyde based adhesive were used in the assembling of glulam beans, according to the adhesive manufacturer\'s instructions. In order to characterize the glue line and the penetration of the adhesive in the preparation of the beans. Two slices were cut from each bean to evaluate the adhesion characteristics by microscopy techniques, using specimens appropriate for each technique. Thus, the glue lines and interphase regions were submitted to polarized light optical microscopy, fluorescence microscopy, scanning electron microscopy, confocal microscopy and X-ray microtomography. Purbond HB S390 and Jowapur 686.60 adhesives presented air bubbles in the glue line after cure, that can be related with shear tests, while the second also presented crystals and evidences of residual tension. MUF and Cascophen do not presented evidences of the presence of any of these elements. The results from the microscopic techniques revealed details of the penetration of the adhesives in each case and occurred in the vessels, lumen of the tracheid and along of the radius and is deeply related to the density of each wood. Microscopic techniques reveled to be complimentary with characteristic information from each one of them. Dyeing of the samples make easier the observation of optical microscopy images being useful in the analysis of residual tension, presence of bubbles and crystals in the adhesive. However, this technique did not allowed the determination of the characteristics of penetration in the samples. Fluorescence microscopy allowed observing of all phases of the glue line, coarse penetration deepness and identification of bubbles, but the results has poor focus and low resolution and requires fluorescent probe. Confocal fluorescence microscopy also allowed the identification of all phases in the glue line, coarse and cell penetration deepness observation, with high resolution and color contrast, however it generated shade in the irregular regions of the sample surface. Scanning electron microscopy permitted the precise determination of the glue line thickness in the pure phase, visualization of the fulfilling of some lumens, but the grey scale can generate doubts concerning the differentiation of the adhesive and wood in the images. X-ray microtomography allowed determining the 3D penetration profile, with high resolution, however it needed that contrast in introduced in the adhesive when testing high density woods. Thus, from this work it was verified the need of using microscopic techniques as complementary tool in studding adhesion in glulam beans. The results of this work point that the microscopic techniques should be part of the standards for gluelam quality testing.