The wooden multi-storey building industry is facing persistent sound transmission problems at low frequencies. Inserting elastomers within wall-floor junctions is common usage nevertheless no accurate studies have elucidated the real behavior of those nonlinear combined materials yet. Deeper knowledge is needed to create a relevant FE model which will help industry to use those materials efficiently.The nonlinear dynamic behavior of the elastomers inserted in wooden junctions is analyzed while the static load acting on them is varying. The specific situation where those elastomers were tested is a scaled room made of two walls and one floor.An experimental study was conducted on this prototype wooden construction and a numerical analysis was performed on the Finite Element model of it. The frequency response functions of several positions were measured on the physical setup.The study showed that loaded structures (up to 2 times the load of the floor) had a lower damping ratio. Having the structure standing on really stiff or elastic material does not differ when comparing experimental and analytical modal parameters.Those results depict the behavior of elastomers for different load cases and are definitely a step forward for the conception of a reliable FE model.

Valve stem seal leakage is a major source of fugitive emissions, and controlling these emissions can result in added expense in leak detection and repair programs. Elastomeric O-rings can be used as valve stem seals, and O-ring manufacturers recommend lubrication of elastomeric seals to prevent damage and to assure proper sealing. In this research, a metallic coating was applied as a lubricant using a vacuum vapor deposition process to the surface of elastomeric valve stem seals. Valve stem leak measurements were taken to determine if the coated O-rings, alone or with the recommended lubrication, reduced valve stem seal leakage. This research determined that the metallic coating did not reduce valve stem leakage.

<p>Biofouling, the accumulation of biomolecules, cells, organisms and their deposits on submerged and implanted surfaces, is a ubiquitous problem across various human endeavors including maritime operations, medicine, food industries and biotechnology. Since several decades, there have been substantial research efforts towards developing various types of antifouling and fouling release approaches to control bioaccumulation on man-made surfaces. In this work we hypothesized, investigated and developed dynamic change of the surface area and topology of elastomers as a general approach for biofouling management. Further, we combined dynamic surface deformation of elastomers with other existing antifouling and fouling-release approaches to develop multifunctional, pro-active biofouling control strategies. </p><p>This research work was focused on developing fundamental, new and environment-friendly approaches for biofouling management with emphasis on marine model systems and applications, but which also provided fundamental insights into the control of infectious biofilms on biomedical devices. We used different methods (mechanical stretching, electrical-actuation and pneumatic-actuation) to generate dynamic deformation of elastomer surfaces. Our initial studies showed that dynamic surface deformation methods are effective in detaching laboratory grown bacterial biofilms and barnacles. Further systematic studies revealed that a threshold critical surface strain is required to debond a biofilm from the surface, and this critical strain is dependent on the biofilm mechanical properties including adhesion energy, thickness and modulus. To test the dynamic surface deformation approach in natural environment, we conducted field studies (at Beaufort, NC) in natural seawater using pneumatic-actuation of silicone elastomer. The field studies also confirmed that a critical substrate strain is needed to detach natural biofilm accumulated in seawater. Additionally, the results from the field studies suggested that substrate modulus also affect the critical strain needed to debond biofilms. To sum up, both the laboratory and the field studies proved that dynamic surface deformation approach can effectively detach various biofilms and barnacles, and therefore offers a non-toxic and environmental friendly approach for biofouling management.</p><p>Deformable elastomer systems used in our studies are easy to fabricate and can be used as complementary approach for existing commercial strategies for biofouling control. To this end, we aimed towards developed proactive multifunctional surfaces and proposed two different approaches: (i) modification of elastomers with antifouling polymers to produce multifunctional, and (ii) incorporation of silicone-oil additives into the elastomer to enhance fouling-release performance.</p><p>In approach (i), we modified poly(vinylmethylsiloxane) elastomer surfaces with zwitterionic polymers using thiol-ene click chemistry and controlled free radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionalities. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. In approach (ii), we incorporated silicone-oil additives in deformable elastomer and studied synergistic effect of silicone-oils and surface strain on barnacle detachment. We hypothesized that incorporation of silicone-oil additive reduces the amount of surface strain needed to detach barnacles. Our experimental results supported the above hypothesis and suggested that surface-action of silicone-oils plays a major role in decreasing the strain needed to detach barnacles. Further, we also examined the effect of change in substrate modulus and showed that stiffer substrates require lower amount of strain to detach barnacles.</p><p>In summary, this study shows that (1) dynamic surface deformation can be used as an effective, environmental friendly approach for biofouling control (2) stretchable elastomer surfaces modified with anti-fouling polymers provides a pro-active, dual-mode approach for biofouling control, and (3) incorporation of silicone-oils additives into stretchable elastomers improves the fouling-release performance of dynamic surface deformation technology. Dynamic surface deformation by itself and as a supplementary approach can be utilized biofouling management in biomedical, industrial and marine applications.</p> / Dissertation

O objetivo do presente trabalho foi quantificar, in vitro e in vivo, a endotoxina bacteriana (LPS) aderida a ligaduras ortodônticas elastoméricas estéticas de poliuretano e de silicone, empregando o teste Limulus Amebocyte Lysate (LAL). Para o estudo in vitro foram utilizadas quatro tipos de ligaduras elastoméricas estéticas: Sani-Ties (poliuretano) e Sili-Ties (silicone), da GAC, e Mini Single Case Ligature Stick (poliuretano) e Synergy&reg; Low-friction ligatures (silicone), da Rock Mountain, sendo 5 contaminadas com solução de endotoxina (controle positivo) e 5 não-contaminadas (controle negativo). Réplicas feitas de fio de amarrilho torcido e de aço inox fundido, de mesmo tamanho e formato das ligaduras elastoméricas, contaminadas ou não com endotoxina, foram usadas como controle. A quantificação de endotoxina foi realizada por meio do teste LAL (Kit QCL-1000&trade;), sendo os resultados expressos em unidades de endotoxina (UE/mL). No estudo in vivo, 20 pacientes de ambos os gêneros, com faixa etária entre 15 e 30 anos, que iniciaram tratamento com aparelho ortodôntico fixo na Faculdade de Odontologia de Ribeirão Preto - Universidade de São Paulo receberam, randomicamente, em quadrantes alternados, os mesmos quatro tipos de ligaduras elastoméricas utilizadas no estudo in vitro, sendo uma ligadura de cada marca inserida nos caninos superiores e inferiores (13, 23, 33 e 43), aleatoriamente. Vinte e um dias após, as ligaduras foram removidas e processadas para quantificação da endotoxina bacteriana, utilizando também o Kit QCL-1000&trade;. Todos os dados obtidos foram submetidos à análise estatística apropriada de acordo com a distribuição dos dados, por meio dos testes de Kruskal-Wallis e pós-teste de Dunn (estudo in vitro) e ANOVA de medidas repetidas e pós-teste de Tukey (estudo in vivo). Todas as análises foram efetuadas por meio do programa Graph Pad Prism 4.0, com nível de significância de 5%. De acordo com os resultados obtidos, observou-se que a endotoxina bacteriana aderiu-se a todos os materiais testados. No estudo in vitro, o grupo GAC silicone foi o que apresentou menor mediana de contaminação (1,15 UE/mL), com relação aos outros grupos (p<0,0001), os quais não apresentaram diferença estatisticamente significante quando comparados entre si (p>0,05). No estudo in vivo, de maneira semelhante ao observado no estudo in vitro, o grupo GAC silicone foi o que apresentou menor média de contaminação (0,577±0,017 UE/mL), com diferença estatisticamente significante (p<0,001) em comparação aos demais grupos. Pôde-se concluir, que a endotoxina bacteriana apresentou afinidade pelas ligaduras elastoméricas estéticas à base de silicone e poliuretano testadas. As ligaduras de silicone da marca GAC foram as que apresentaram menor quantidade de endotoxina aderida às suas superfícies / The objective of this study was to quantify, in vitro and in vivo, bacterial endotoxin (LPS) attached to esthetic elastomeric orthodontic ligatures made of polyurethane and silicone using the Limulus Amebocyte Lysate test (LAL). For the in vitro study, were used four types of aesthetic elastomeric ligatures: Sani-Ties (polyurethane) and Sili-Ties (silicone) - GAC, and Mini Single Case Ligature Stick (polyurethane) and Synergy&reg; Low-friction ligatures (silicone) - Rock Mountain; 5 of each were contaminated with endotoxin solution (positive control) and 5 non-contaminated (negative control). Replicas made of twisted wire ligatures and of cast stainless steel, of the same size and shape than the elastomeric ligatures, contaminated or not with endotoxin, were used as control. Endotoxin quantification was performed using the LAL test (QCL-1000&trade; kit), the results being expressed in EU/mL. In the in vivo study, 20 patients of both genders, with ages ranging from 15 to 30 years old, who started treatment with a fixed orthodontic appliance at the School of Dentistry of Ribeirão Preto - University of São Paulo, received randomly the same four types of elastomeric ligatures used in the in vitro study, being a ligature of each brand inserted in the upper and lower canines (UR3, UL3, LR3, LL3), randomly. Twenty-one days later, ligatures were removed and processed for quantification of bacterial endotoxin, using the same test as the in vitro study. All data were submitted to appropriate statistical analysis according to the data distribution, using KruskalWallis tests and Dunn post-test (in vitro study) and ANOVA of repeated measurements and Tukey\'s post-test (in vivo study). All analyzes were performed using the Graph Pad Prism 4.0 program, with a significance level of 5%. According to the results obtained, it was observed that the bacterial endotoxin attached to all materials tested. In the in vitro study, the GAC silicone group had the lowest median contamination (1.15 EU/mL), in relation to the other groups (p<0.0001), which did not present a statistically significant difference when compared to each other (p>0.05). In the in vivo study, similar to that observed in the in vitro study, the GAC silicone group had the lowest mean contamination (0.577 ± 0.017 EU/mL), with a statistically significant difference (p< 0.001) compared to the others groups. It could be concluded that bacterial endotoxin exhibited affinity for the tested silicone and polyurethane aesthetic elastomeric ligatures. The silicone ligatures of GAC brand were the ones that presented less amount of endotoxin attached to their surfaces

L'ajout de charges (agrégat de taille submicronique) dans une matrice élastomère apporte des propriétés physiques qualitativement différentes de celles de la matrice pure : module complexe dépendant de la température, forts effets non linéaires, forte dissipation... Ces propriétés sont liées à la nature de la matrice et des charges, à leur fraction volumique, et enfin à la force des interactions charge / matrice. Nous présentons d'abord les différents systèmes et la caractérisation de leurs propriétés mécaniques, de façon à clarifier le rôle des différents paramètres.La cristallisation sous traction du caoutchouc naturel a un effet important sur ses propriétés mécaniques. Nous l'avons donc mesurée quantitativement dans chacune des formulations. Nous montrons que le taux de cristallisation à la rupture est toujours de l'ordre de 13%. La nature de l'interface silice / matrice a un effet sur les propriétés mécaniques mais pas sur la cristallisation. Nous avons ensuite étudié le comportement en traction simple d'échantillons pré-entaillés. Nous montrons que la plus grande résistance à la propagation d'entaille du caoutchouc naturel renforcé est corrélée à la présence d'instabilités de propagation (rotation d'entaille). Les mécanismes physiques à l'origine de la rotation d'entaille ne sont pas compris. Nous décrivons la dynamique de propagation des rotations à différentes échelles, et les caractéristiques des rotations.La combinaison de la cristallisation induite et de la présence des charges induit dans le matériau une très grande anisotropie qui pourrait être à l'origine des rotations. / The subject of this PhD thesis is the resistance to tear of reinforced elastomers. The general context of this work is related to the performances of reinforced elastomers, specifically silica reinforced natural rubber, as regards various usage properties : wear of tyre tread, fatigue and tear resistance of tyre flanks, etc. Wear and fatigue mechanisms are very complex. This PhD thesis is a first step towards understanding these mechanisms. We focussed on the parameters which control ultimate properties (resistance to failure, resistance to tear propagation) of uniaxially stretched samples. Reinforced elastomers are nanocomposite materials made of an elastomer matrix in which submicrometric filler particles or aggregates are dispersed. Adding fillers considerably enhances usage properties, specifically ultimate properties. Mechanical and physical properties qualitatively different from those of the pure elastomer matrix are induced: a strongly temperature dependent complex modulus, strong non linear effects (Payne effect), large dissipation, hysteresis, plasticity and long time recovery (Mullins effect). The material parameters which have an influence on the properties are: the nature of the elastomer matrix (natural or synthetic rubber) and of the reinforcing fillers (carbon black or silica), the volume fraction and dispersion state of the fillers, the nature and strength of interactions at filler-matrix interfaces.This work is an experimental study of the resistance to failure and to tearing of uniaxially stretched samples. The various systems which have been studied are presented first. Their mechanical properties have been characterized in the various regimes of strain amplitude. The various samples have been compared systematically in order to clarify the effect of the various material parameters.Natural rubber crystallizes under strain. This phenomenon is very sensitive to the formulation of the various materials and has a tremendous effect on mechanical and ultimate properties. Thus, we have measured quantitatively the amount of crystallinity induced as a function of the applied strain during elongation cycles and up to sample failure. The influence of the nature and volume fraction of the fillers and of the matrix-filler interfaces has been studied. The crystallinity is close to 13% in all studied materials. In samples filled with silica, the nature of the filler-matrix interactions (covalent coupling vs no coupling) has very little influence on crystallization, whereas it modifies strongly the mechanical properties.Then we have studied the resistance to failure of uniaxially stretched pre-notched test samples. Within a macroscopic approach, we have related the ultimate property (energy density at break) to the various tear propagation modes which are observed. We have studied the effect of temperature and drawing speed. It has been shown that the higher resistance to failure of reinforced natural rubber is related to the appearance of spectacular instabilities of the propagation direction (the so-called ‘tear rotation’). The appearance of tear rotation is specific to pre-notched reinforced natural rubber samples. The physical mechanisms responsible for tear rotation are not yet fully understood. The combination of reinforcement due to fillers and of strain-induced crystallization may lead to a strong anisotropy of the elastic material constant of the material in front of the tear tip, and this might be the driving force for tear rotation. The rotation length has been identified as an important parameter which correlates well to the ultimate properties. The tear propagation is described at various scales. The typical length scales associated to tear rotation which are observed have been related to the material properties.

Os elásticos ortodônticos intermaxilares são dispositivos auxiliares importantes para o tratamento ortodôntico. Os objetivos dessa pesquisa foram: comparar a intensidade de força dos elásticos informada pelos fabricantes com a força após estiramento de três vezes o diâmetro interno e avaliar o decaimento de força dos elásticos ortodônticos de várias empresas comerciais (Uniden, Morelli, Orthometric, Aditek, Rocky Mountain, TP Orthodontics e GAC Dentsply) de quatro tamanhos diferentes de diâmetro interno (1/8\"; 3/16\"; 1/4\" e 5/16\") com intensidade de força leve e média. Para esta pesquisa foi desenvolvido um dispositivo para simular os movimentos mandíbulo-maxilar durante a fala. Os elásticos foram submetidos a teste dinâmico e estático, por um período de 24 horas. Durante o teste, os elásticos, foram estirados ao comprimento de três vezes o diâmetro interno, de acordo com o índice de extensão padrão informado pelos fabricantes. Em seguida, iniciou-se o teste dinâmico, no qual, os elásticos eram alongados por mais 11mm correspondendo a distância maxilo-mandibular durante a fala, a uma frequência de 5 Hz. Esse ciclo repetiu-se por 10 minutos a cada hora durante 10 horas. Em três períodos os elásticos não participaram de nenhum teste, ou seja, foram removidos do dispositivo, simulando os horários das refeições. Completando assim o tempo de 12 horas do período diurno. Nos períodos restantes, 12 horas, os elásticos permaneceram em teste estático, ou seja, mantiveram estirados a 3 vezes o diâmetro interno, correspondendo ao período noturno do paciente no qual não apresenta movimento mandibulares significativos. As leituras das tensões-força geradas pelos elásticos foram realizadas por meio de um dispositivo de leitura de força modificada para mensurar elásticos quando estirados a distância de três vezes o lúmen. A leitura ocorreu a cada ciclo durante as primeiras 12 horas, uma inicial e a última ocorreu 24 horas após o início do teste, totalizando 14 leituras. Em função das características da amostra o teste estatístico utilizado foi o teste t de Student, ANOVA e teste Scott-Knott. A maior parte dos elásticos apresentaram diferença entre a força encontrada nesta pesquisa e a força informada pelo fabricante. Os elásticos com diâmetro interno de 1/8\" apresentaram ruptura durante os testes. Nos elásticos com diâmetro 3/16\" de intensidade de força leve, as empresas com melhores desempenhos foram: Morelli, Aditek, Uniden, GAC Dentsply, Orthometric, Rocky Mountain e TP Orthodontics. Nos elásticos com mesmo diâmetro, porém com intensidade de força média, a empresa com menor decaimento de força foi a Uniden, seguido por Morelli, GAC Dentsply, Rocky Mountain, Aditek, Orthometric, TP Orthodontics. Nos elásticos 1/4\" com intensidade de força leve, as empresas com menores decaimentos de forças formaram: Uniden, GAC Dentsply, Morelli, Rocky Mountain, TP Orthodontics, Aditek e Orthometric. Os elásticos 1/4\" com intensidade de força média, as empresas com menores decaimentos de forças foram: Uniden, seguido por Rocky Mountain, Morelli, Aditek, TP Orthodontics, GAC Dentsply e Orthometric. Os elásticos 5/16\" com intensidade de força leve, os elásticos da empresa Uniden apresentaram menores decaimentos de forças, seguido por GAC Dentsply, Aditek, Morelli, Rocky Mountain, Orthometric e TP Orthodontics. Nos elásticos 5/16\" de intensidade de força média, as empresas com menores decaimentos de forças foram: Uniden, Rocky Mountain, Morelli, GAC Dentsply, Aditek, Orthometric e TP Orthodontics. Em seguida à análise dos resultados, conclui-se que o maior decaimento de força dos elásticos ocorreram na primeira hora de teste, em média 12,78%, em seguida, a esse período, ocorre um decaimento de menor intensidade de força, em média de 6,95%, durante o período de 24 horas. Sendo indicado as trocas dos elásticos diariamente. / Intermaxillary latex orthodontic elastics are important auxiliary devices for orthodontic treatment. This study aimed to assess force decay of several commercial brands (Uniden, Morelli, Orthometric, Aditek, Rocky Mountain, TP Orthodontics, and GAC Dentsply) and four sizes (1/8\"; 3/16\"; 1/4\"; and 5/16\") with low and median force intensity. A device that simulates mandibular and maxillary speech movement of patients was developed for this research. The elastics were simultaneously subjected to dynamic and static tests for 24 hours. During the static test, the elastics were stretched three times the distance of the inner diameter, as recommended by the manufacturers. Next, the dynamic test began, where the elastics were stretched by an additional 11 mm, which corresponds to the maxillary and mandibular distance during speech, at a 5 Hz rate. This cycle was repeated for 10 minutes every 10 hours. In three periods, the elastics did not participate of any test, meaning they were removed from the device to simulate meal times; thus, the 12-hour daytime was completed. Over the 12 hours remaining, the elastics were maintained in static test, meaning they were stretched three times the inner diameter, which corresponds to the night time of the patient, who did not present significant mandibular movements. Force readings were performed at each cycle over the first 12 hours, and the last reading was performed 24 hours after the beginning of the test. Due to the characteristic of the sample, the statistical tests used were Student t test, ANOVA, and Scott-Knott test. Most of the elastics presented difference between the force found in this research and the one informed by the manufacturer. The 1/8\" (3.2 mm) elastics showed rupture during tests. In the 3/16\" (4.8 mm) elastics with low force intensity, the best-performing brands were Morelli, Aditek, Uniden, GAC Dentsply, Orthometric, Rocky Mountain, and TP Orthodontics over 24 hours of testing. In elastics with the same diameter but median force intensity, the brand with less force decay was Uniden, followed by Morelli, GAC Dentsply, Rocky Mountain, Aditek, Orthometric, and TP Orthodontics. In the 1/4\" elastics with light force intensity, the brands with less force decay were Uniden, GAC Dentsply, Morelli, Rocky Mountain, TP Orthodontics, Aditek, and Orthometric. In the 1/4\" elastics with medium force intensity, the brand with less force decay was, again, Uniden, followed by Rocky Mountain, Morelli, Aditek, TP Orthodontics, GAC Dentsply, and Orthometric. In the 5/16\" (7.9 mm) elastics with light force intensity, the brand Uniden presented better performance, followed by GAC Dentsply, Aditek, Morelli, Rocky Mountain, Orthometric, and TP Orthodontics. In the 5/16\" elastics with median force intensity, the brands with less force decay were Uniden, Rocky Mountain, Morelli, GAC Dentsply, Aditek, Orthometric, and TP Orthodontics. After the analysis of results, it was concluded that the greatest force decay of elastics occurred in the first hour of testing with 12.78% in average; after this period, there was a reduced force decay of 6.95% in average, over 24 hours. Daily changes of elastics are recommended.

A reciclagem de diversos tipos de materiais tem adquirido importância nos últimos anos. Problemas ambientais graves como o acúmulo de rejeitos e a poluição atmosférica, causados pelo crescente consumo de materiais poliméricos, incentivam estudos para o desenvolvimento de diferentes formas de reaproveitamento. Entretanto, a reciclagem de polímeros elastômeros tem demonstrado grande complexidade, pois o material depois de vulcanizado não pode ser remoldado pelo simples aquecimento. A desvulcanização por microondas é uma técnica promissora para contornar este problema, uma vez que possibilita restituir a capacidade de moldagem dos elastômeros. Neste trabalho foi feito um estudo sobre a desvulcanização por micro-ondas em processo contínuo e em batelada do elastômero estireno-butadieno (SBR) com diferentes quantidades de negro de fumo e em diferentes condições de processamento, de modo a avaliar os processos de desvulcanização e esclarecer melhor os fenômenos e reações químicas envolvidas. A eficiência dos diferentes sistemas de desvulcanização adotados foi avaliada por meio de análises termogravimétricas (TG), dinâmico-mecânicas (DMA), calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho (FTIR), espectrometria de ressonância magnética nuclear (RMN), densidade de ligação cruzada e teor de gel. A desvulcanização foi mais efetiva no elastômero SBR com maiores teores de negro de fumo, empregando o sistema de desvulcanização em batelada com uma única fonte de radiação, enquanto que a desvulcanização contínua não apresentou resultados relevantes para o sistema adotado. O material desvulcanizado demonstrou mudanças químicas e físicas consideráveis na sua estrutura. Assim, a reciclagem de elastômeros utilizando a energia das micro-ondas torna-se possível e provoca mudanças estruturais no material para borracha com altos teores de negro de fumo utilizando o sistema batelada. / The recycling of several materials has acquired importance in the last few years. Serious environmental problems as the increase in waste material and air pollution, caused by the growing consumption of polymeric material, stimulate works to development of distinct ways of reclamations. However, the recycling of elastomers has demonstrated more complexity than other polymeric materials because, after vulcanized, the material can not be remolded by simple heating. The microwave devulcanization is a promissory technique to solve this problem, in as it makes it possible to replace the remold capacity of elastomers. In this work it was studied the devulcanization by microwave in continuous and batch processes of styrene-butadiene rubber (SBR) with different amount of carbon black (CB) and in different process conditions, to evaluate the devulcanization process and to clarify the involved phenomena and chemical. The efficiency of distinct devulcanization systems was evaluated through thermogravimetric analyses (TG), dynamic-mechanical analysis (DMA), differential scattering calorimetric (DSC), Fourier transformed infrared (FTIR), nuclear magnetic resonance (NMR), crosslink density and gel content analysis. The devulcanization was more effective in SBR elastomer with higher amount of carbon black, used the batch systems devulcanization with a single source of radiation, whereas the continuous devulcanization did not show relevant results to the adopted system. The devulcanized material exhibited considerable chemical and physical alteration in its structure. Thus, the elastomers recycling using the microwave energy is possible and generates structural modification in the material for rubber with high amount of carbon black in batch system.

Este estudo avaliou a dureza Shore A, alteração de cor, recuperação elástica e resistência ao rasgamento de um silicone experimental (Ortho Pauher - O), quando comparado a um silicone usado em reabilitações faciais (MDX 4-4210 - MDX), quando submetidos à pigmentação e envelhecimento e ainda, analisou a micro estrutura desses materiais. Para análise da alteração de cor e dureza foram obtidos 160 espécimes circulares (80/material); para os ensaios de recuperação elástica foram obtidos 200 espécimes cilíndricos (100/material) e para o ensaio de resistência ao rasgamento, foram confeccionados 200 espécimes em forma de calça (100/material). Metade dos espécimes recebeu pigmentação intrínseca e a outra metade, pigmentação intrínseca e extrínseca, por meio da adição de pó de maquiagem. Em seguida, foram distribuídos aleatoriamente em três grupos de envelhecimento: 1 termociclagem (T), 2 - luz ultravioleta (UV) e 3 - luz natural (LN). O envelhecimento simulou um período de uso de um ano. Como controle (C), os espécimes foram mantidos em um recipiente fechado e na ausência total de luz por um ano. Para as análises micro estruturais, três espécimes de cada grupo foram submetidos à Microscopia Eletrônica de Varredura (MEV), Espectroscopia no Infravermelho (EI), Calorimetria Exploratória Diferencial (DSC) e Termogravimetria (TG). Os dados foram submetidos à Análise de variância e Teste Complementar de Tukey (p<0,05). Os resultados das análises micro estruturais foram apresentados em tabelas e gráficos. Para alteração de cor, não houve diferença entre os materiais e pigmentação. Os envelhecimentos por UV, LN e T promoveram a maior alteração. O MDX apresentou alterações em função da PIE, T e UV e o Ortho Pauher, em função da PI/UV e PIE/T e UV. Para a dureza, o silicone Ortho e a PI apresentaram as maiores alterações, bem como a LN e a UV. Ambos os materiais variaram em função das pigmentações e envelhecimento. Para resistência ao rasgamento houve diferença para todos os fatores e para a interação. O silicone O e a PI promoveram as menores médias. O MDX sofreu alteração em função da pigmentação e do envelhecimento. Na recuperação elástica, o material M apresentou a maior média, bem como o grupo PIE. Para o envelhecimento, a UV resultou em menor recuperação e os maiores valores foram encontrados no C e LN. Os dois materiais variaram em função da pigmentação e envelhecimento. As análises micro estruturais demonstraram que a polimerização dos materiais foi completa e que os pigmentos adicionados, nas proporções utilizadas, não influenciaram na estabilidade dos materiais. O resultado do estudo sugere que as alterações encontradas nas propriedades físico-mecânicas, em função da exposição às diferentes pigmentações e envelhecimento não representam diferenças estruturais importantes e que o silicone experimental merece estudos com vistas em sua aplicabilidade clínica e que o silicone experimental precisa ser estudado com vistas em sua aplicabilidade clínica. / This study evaluated the color change, Shore A hardness, tear resistance and elastic recovery of an experimental silicone (Ortho Pauher - O), compared to a silicone used in facial rehabilitation (MDX 4-4210 - MDX), when submitted to pigmentation and accelerated aging and also examined the microstructure of these materials. To analyze the color change and hardness, we were obtained 160 circular specimens (80/material); for the elastic recovery, 200 cylindrical specimens were obtained (100/material) and for the tear strength, 200 specimens were fabricated in the form of pants (100/material). Half of the samples received intrinsic pigmentation and the other half received intrinsic and extrinsic pigmentation, also by applying makeup powder. Subsequently, the specimens were randomly distributed into three groups of aging: 1 - thermocycling (T), 2 - ultraviolet light (UV) and 3 - natural light (NL). All of the aging steps simulated a period of 1-year. As a control (C), the specimens were kept in a closed container in total absence of light for 1-year. For the micro structural analysis, three specimens of each group were subjected to Scanning Electron Microscopy (SEM), Infrared Spectroscopy (EI), Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG). For statistical analysis tests were used ANOVA and Tukeys test (p<0.05). For the micro structural analysis, the results were presented in tables and graphs. For color change, there was no difference between the materials and pigmentation. The UV, LN and T aging, promoted the greatest change. MDX was altered in function of the IEP, T and UV and Ortho Pauher, according to the PI/UV and IEP/T and UV. For hardness, Ortho Pauher silicone and IP showed the greatest changes, as well as the LN and UV. Both materials varied depending on the pigmentation and aging. For tear strength, difference was found for all factors and interaction. The Silicone Ortho Pauher and IP promoted the lowest averages. The MDX was altered depending of the pigmentation and aging. In the elastic recovery, the material M and the PIE group showed the highest average. For aging, UV resulted in lower recovery and higher values were found in the C and LN. The two materials were changed according to pigmentation and aging. The micro structural analyzes showed that the polymerization was completed and the material and the pigments added, in the proportions used, do not influence the stability of the materials. The study results suggest that the changes found in physical-mechanical properties, depending on exposure to different pigmentation and aging, do not represent important structural alterations and the experimental silicone needs to be studied with a view to its clinical applicability.

Diante da necessidade de produzir uma vedação com maior vida útil frente as condições de descompressão explosiva de CO2 incorporou-se quantidades diferentes de MWCNT (multiwalled carbono nanotubes) curtos e longos (0,25 phr e 1 phr) e com graus de funcionalidade de grupos oxigenados variando entre 0% e 7,5% em elastômeros fluorados. A incorporação foi realizada utilizando-se o processo de mistura em cilindro aberto (Copê) e as mantas de borracha obtidas foram termoprensadas e submetidas a doses de irradiação de 5, 10 e 20 kGy em ar atmosférico. Analisaram-se os nanocompósitos e os MWCNT por análises térmicas, difrações de raios-X e micrografias. A partir dos nanocompósitos também foram confeccionados corpos de prova para ensaios mecânicos, análises dinâmico-mecânicas, ensaios de dessorção. Os resultados indicaram em geral aumento dos módulos a 100% e secante a 15% nas amostras com adição de 1 phr, mas pouca mudança da temperatura de transição vítrea foi observada, indicando pouca alteração da mobilidade das cadeias. As micrografias apontaram algumas extremidades de MWCNT soltas da matriz polimérica após o processo de preparação da amostra. Os resultados apontaram melhora na dessorção dos nanocompósitos após a incorporação dos MWCNT. / Faced with the need to produce a gasket with longer useful life against the explosive decompression conditions of CO2, it was incorporated different amounts of short and long MWCNT (0.25 phr and 1 phr) and degrees of oxygenated groups functionality ranging between 0% and 7.5% in fluorinated elastomers. The incorporation was performed using the open mill with two rolls (COPE) and rubber blankets were obtained thermopressed and subjected to radiation doses of 5, 10 and 20 kGy in air atmosphere. Nanocomposites and MWCNT were analyzed by thermal analysis, X-ray diffraction and SEM micrographs. From the nanocomposites were also prepared specimens for mechanical testing, dynamic mechanical analysis, desorption tests. The results indicated, in generally, an increase of modules to 100% and secant to 15% in the samples with the addition of 1 phr, however little change in the glass transition temperature was observed, indicating little variation of mobility of the chains. The micrographs showed some free ends of MWCNT the polymer matrix after sample preparation process. The results pointed improvement on dessorpotion of nanocomposites after the incorporation of MWCNT.

Este estudo avaliou a dureza Shore A, alteração de cor, recuperação elástica e resistência ao rasgamento de um silicone experimental (Ortho Pauher - O), quando comparado a um silicone usado em reabilitações faciais (MDX 4-4210 - MDX), quando submetidos à pigmentação e envelhecimento e ainda, analisou a micro estrutura desses materiais. Para análise da alteração de cor e dureza foram obtidos 160 espécimes circulares (80/material); para os ensaios de recuperação elástica foram obtidos 200 espécimes cilíndricos (100/material) e para o ensaio de resistência ao rasgamento, foram confeccionados 200 espécimes em forma de calça (100/material). Metade dos espécimes recebeu pigmentação intrínseca e a outra metade, pigmentação intrínseca e extrínseca, por meio da adição de pó de maquiagem. Em seguida, foram distribuídos aleatoriamente em três grupos de envelhecimento: 1 termociclagem (T), 2 - luz ultravioleta (UV) e 3 - luz natural (LN). O envelhecimento simulou um período de uso de um ano. Como controle (C), os espécimes foram mantidos em um recipiente fechado e na ausência total de luz por um ano. Para as análises micro estruturais, três espécimes de cada grupo foram submetidos à Microscopia Eletrônica de Varredura (MEV), Espectroscopia no Infravermelho (EI), Calorimetria Exploratória Diferencial (DSC) e Termogravimetria (TG). Os dados foram submetidos à Análise de variância e Teste Complementar de Tukey (p<0,05). Os resultados das análises micro estruturais foram apresentados em tabelas e gráficos. Para alteração de cor, não houve diferença entre os materiais e pigmentação. Os envelhecimentos por UV, LN e T promoveram a maior alteração. O MDX apresentou alterações em função da PIE, T e UV e o Ortho Pauher, em função da PI/UV e PIE/T e UV. Para a dureza, o silicone Ortho e a PI apresentaram as maiores alterações, bem como a LN e a UV. Ambos os materiais variaram em função das pigmentações e envelhecimento. Para resistência ao rasgamento houve diferença para todos os fatores e para a interação. O silicone O e a PI promoveram as menores médias. O MDX sofreu alteração em função da pigmentação e do envelhecimento. Na recuperação elástica, o material M apresentou a maior média, bem como o grupo PIE. Para o envelhecimento, a UV resultou em menor recuperação e os maiores valores foram encontrados no C e LN. Os dois materiais variaram em função da pigmentação e envelhecimento. As análises micro estruturais demonstraram que a polimerização dos materiais foi completa e que os pigmentos adicionados, nas proporções utilizadas, não influenciaram na estabilidade dos materiais. O resultado do estudo sugere que as alterações encontradas nas propriedades físico-mecânicas, em função da exposição às diferentes pigmentações e envelhecimento não representam diferenças estruturais importantes e que o silicone experimental merece estudos com vistas em sua aplicabilidade clínica e que o silicone experimental precisa ser estudado com vistas em sua aplicabilidade clínica. / This study evaluated the color change, Shore A hardness, tear resistance and elastic recovery of an experimental silicone (Ortho Pauher - O), compared to a silicone used in facial rehabilitation (MDX 4-4210 - MDX), when submitted to pigmentation and accelerated aging and also examined the microstructure of these materials. To analyze the color change and hardness, we were obtained 160 circular specimens (80/material); for the elastic recovery, 200 cylindrical specimens were obtained (100/material) and for the tear strength, 200 specimens were fabricated in the form of pants (100/material). Half of the samples received intrinsic pigmentation and the other half received intrinsic and extrinsic pigmentation, also by applying makeup powder. Subsequently, the specimens were randomly distributed into three groups of aging: 1 - thermocycling (T), 2 - ultraviolet light (UV) and 3 - natural light (NL). All of the aging steps simulated a period of 1-year. As a control (C), the specimens were kept in a closed container in total absence of light for 1-year. For the micro structural analysis, three specimens of each group were subjected to Scanning Electron Microscopy (SEM), Infrared Spectroscopy (EI), Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG). For statistical analysis tests were used ANOVA and Tukeys test (p<0.05). For the micro structural analysis, the results were presented in tables and graphs. For color change, there was no difference between the materials and pigmentation. The UV, LN and T aging, promoted the greatest change. MDX was altered in function of the IEP, T and UV and Ortho Pauher, according to the PI/UV and IEP/T and UV. For hardness, Ortho Pauher silicone and IP showed the greatest changes, as well as the LN and UV. Both materials varied depending on the pigmentation and aging. For tear strength, difference was found for all factors and interaction. The Silicone Ortho Pauher and IP promoted the lowest averages. The MDX was altered depending of the pigmentation and aging. In the elastic recovery, the material M and the PIE group showed the highest average. For aging, UV resulted in lower recovery and higher values were found in the C and LN. The two materials were changed according to pigmentation and aging. The micro structural analyzes showed that the polymerization was completed and the material and the pigments added, in the proportions used, do not influence the stability of the materials. The study results suggest that the changes found in physical-mechanical properties, depending on exposure to different pigmentation and aging, do not represent important structural alterations and the experimental silicone needs to be studied with a view to its clinical applicability.