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Exposé aux intempéries, le bois est sujet à des dégradations esthétiques et subit des variations dimensionnelles dues aux alternances de périodes sèches et humides. Son utilisation en extérieur nécessite donc l’application d’une finition (peinture, lasure) pour le protéger. Le revêtement doit être assez souple pour suivre les variations du bois tout en étant assez dur pour résister à de potentiels impacts (grêle). Les performances mécaniques du revêtement jouent donc un rôle primordial dans sa durée de vie. Pourtant, actuellement en Europe, les performances des revêtements sont principalement évaluées à travers des tests de vieillissement suivis d’évaluations visuelles, de mesures de couleur et de brillance et de mesures d’adhérence. L’objectif de ce travail est de mettre en place une méthodologie approfondie d’évaluation des performances des revêtements afin de mieux comprendre les phénomènes régissant le vieillissement des revêtements. La finalité de ce projet est le développement industriel de revêtements innovants sur bois pour un emploi extérieur avec de bonnes performances tout au long de leur durée de service. A travers notre étude, les performances de revêtements traditionnels ont été évaluées avec les tests obligatoires dans la série de norme EN 927 ainsi qu’avec d’autres méthodes (destructives et non destructives) permettant d’avoir une connaissance approfondie de leurs propriétés physico-mécaniques. Ainsi, des mesures de dureté pendulaire, d’extensibilité du revêtement par indentation ou encore des tests de traction sur films libres ont été réalisés. Le pendule de Persoz a particulièrement été investigué comme un outil permettant d’avoir une approche simple et rapide des propriétés mécaniques du revêtement. Ce travail a démontré un lien entre la dureté pendulaire et les performances des revêtements. Les tests de traction de films libres ont permis d’étayer ces résultats en démontrant une corrélation entre la dureté pendulaire et certaines propriétés mécaniques. Enfin, l’étude des variations de dureté pendulaire au cours du vieillissement a permis de mieux comprendre l’apparition des dégradations et a conduit à l’établissement de seuils de performance. Ces résultats ont permis la sélection et l’élaboration de nouvelles formulations photopolymérisables adaptées à une utilisation extérieure. Celles-ci sont constituées d’un mélange de monomères polyfonctionnels (ou diluants réactifs) et d’oligomère(s) combiné(s) à un photoamorceur. Ces différents constituants ont été sélectionnés permettant le développement d’une formulation avec de bonnes performances au vieillissement / Wood used outdoors is subject to aesthetic damages and to dimensional variations due to alternation of dry and wet periods. Therefore, a protection with a coating is recommended. Coatings need to be soft enough to follow variations of wood and at the same time hard enough to be able to withstand possible damages (impact). Hence, mechanical properties of coatings play a major role in their service life. However in Europe, coating performances are mainly assessed through weathering tests followed by visual assessments, color and gloss measurements and adherence tests. The aim of this work is to develop a thorough methodology to assess coating performances in order to better understand the resistance of coatings to weathering. The final objective of this project is an industrial development of innovating wood coatings for outdoors with good performances to weathering during their service life. Through our study, performances of commercial coating were assessed using conventional standardized tests from the EN 927 series but also with other methods in order to gain an extensive understanding of their physic-mechanical properties. Hence, damping and indentation tests on coated wood were investigated as well as tensile tests on free films. Persoz pendulum was particularly used as a tool to approach easily and quickly mechanical properties of coatings. This work established a link between damping test results and coating performances exposed to artificial and natural weathering. Tensile tests on free films have supported these results as a good correlation between damping hardness and some mechanical properties was found. Last but not least, the analysis of damping hardness variations versus weathering time has lead to a better understanding in the development of damages and to the establishment of performance specifications. These results allowed us to select and formulate new UV-curing formulations for outdoors. They are made of a mixture of monomers and oligomers combined with photoinitiators. At this stage, the methodology developed to assess performances has allowed the selection of the best constituents to ensure good performances to weathering

Em 2012 foram gastos em torno de 80 bilhões de dólares com problemas relacionados à corrosão de materiais metálicos, entre eles custos diretos e indiretos em manutenções corretivas e preventivas. Esse elevado valor evidencia a importância de se trabalhar na proteção contra a corrosão. Há diversas maneiras de se mitigar os danos causados pelo fenômeno da corrosão em materiais metálicos, sendo uma delas o pré-tratamento dessas superfícies com camadas de conversão. O objetivo do presente trabalho é estudar o comportamento de um dos materiais mais utilizados na indústria automobilística, o aço galvannealed, depois de submetido a um pré-tratamento de superfície baseado na aplicação de um filme fino de sulfossilano seguido de pintura com tintas industriais. O desempenho do filme de silano foi comparado a um dos processos de pré-tratamento mais usuais do mercado brasileiro, que é a fosfatização. Após o desengraxe e limpeza do substrato com solução alcalina, o mesmo foi imerso por 15 minutos em uma solução de água e álcool (50/50 m/m) contendo 3% do silano bis-1,2-[trietoxisililpropil] tetrasulfeto (BTESPT), aditivada com 50 ppm de íons de Ce (IV). Depois de curar por 40 minutos a 150°C, obteve-se o filme de sulfossilano. Após o preparo dos corpos de prova com a aplicação do pré-tratamento, foi aplicada uma camada de revestimento orgânico tinta de fundo alquídica e tinta epóxi base água e o sistema secou ao ar por 15 dias. A avaliação desses sistemas teve como base testes eletroquímicos para avaliação de desempenho do filme e do revestimento orgânico, como as medidas de espectroscopia de impedância eletroquímica. Também foram feitos ensaios acelerados de corrosão com exposição dos corpos de prova recobertos em câmara de névoa salina (salt spray test) e imersão em água deionizada, além de medidas de aderência e flexibilidade dos revestimentos aplicados. Os resultados obtidos permitem afirmar que o filme de silano produzido a partir de BTESPT aditivado com íons de Ce (IV), aplicado sobre aço galvannealed, confere excelente proteção contra corrosão, mesmo quando comparado ao pré-tratamento mais comum de mercado a fosfatização tendo apresentado bom desempenho em todos os testes realizados, com destaque para os ensaios de impedância eletroquímica, exposição à névoa salina e imersão em água deionizada. / In 2012 around 80 billion dollars were spent with matters related to corrosion, including direct and indirect costs regarding corrective and preventive maintenance. The amount spent highlights the importance of working on the protection against corrosion. There are several ways to mitigate the damage caused by corrosion phenomenum in metals; one of them is the surface pretreatment with conversion layers. The objective of the present work is to study the behavior of galvannealed steel, one of the most used materials in automotive industry, after being pretreated with a thin layer of sulfursilane and coated with industrial paints. The performance of the silane film was compared to one of the most usual pretreatments in place, which is phosphatizing. After degreasing and cleaning the substrate with alkaline solution, the specimen was immersed for 15 minutes in a water/alcohol solution (50/50 w/w) containing 3% of bis-1,2-[triethoxysilylpropyl]tetrasulfide (BTESPT), dopped with 50 ppm of Ce (IV) ions. After curing for 40 minutes at 150ºC, the sulforsilane film was obtained. The organic coatings alkyd primer and waterborne epoxy coatings were applied over the silane and phosphate pretreatments and the systems dried for 15 days. Electrochemical impedance spectroscopy was used to evaluate the performance of the pretreatment layers combined with organic coatings. Accelerated corrosion tests, such as salt spray test and immersion in deionized water, were also performed, along with physical tests like adhesion and flexibility. Based on the results, it is possible to affirm that the silane thin film obtained from BTESPT dopped with Ce (IV) ions and applied over galvannealed steel offers excellent protection against corrosion, even if compared to the most common pretreatment currently in place phosphate conversion layer. It performed well in all tests carried out, especially the electrochemical impedance spectroscopy, salt spray test and immersion in deionized water.

Orientador: Osvaldir Pereira Taranto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T09:03:35Z (GMT). No. of bitstreams: 1 Silva_MarcioWagnerda_M.pdf: 1218438 bytes, checksum: eceeeda826d1358b20dfb5259a2bbf6f (MD5) Previous issue date: 2006 / Resumo: O processo de recobrimento de microgrânulos em Leito Fluidizado Pulsado-Rotativo (LFPR) foi investigado através da realização de experimentos de revestimento de celulose microcristalina (MICROCEL). Foi analisada e discutida a influência da carga de partículas, freqüência de pulsação da corrente gasosa, vazão de suspensão, pressão de atomização e temperatura de secagem sobre a eficiência de recobrimento, crescimento relativo em massa e índice de aglomerados. O principal objetivo do desenvolvimento do trabalho foi avaliar o desempenho e o comportamento do processo de recobrimento de microgrânulos em um equipamento de leito fluidizado com alimentação pulsada da corrente gasosa, frente a um equipamento de leito fluidizado convencional, cujo comportamento é amplamente descrito na literatura. Para a investigação do processo de recobrimento foi utilizada uma suspensão polimérica à base de Eudragitâ, e partículas de MICROCEL com diâmetro na faixa de 0,25 a 0,42 mm. O crescimento relativo médio das partículas foi de 3,63 %. Os experimentos foram realizados segundo técnicas de planejamento experimental, em que as análises dos resultados experimentais obtidos foram realizadas através da Metodologia da Superfície de Resposta. A análise dos efeitos das variáveis sobre as variáveis de resposta do processo foram utilizadas na construção de um modelo empírico, visando, quando possível, a predição do comportamento do processo. A análise dos modelos obtidos foi realizada através da análise de variância (ANOVA). As variáveis independentes analisadas foram: vazão de suspensão (Ws), pressão de atomização (Pat), temperatura do ar (Tar), carga de partículas no leito (M) e freqüência de pulsação (f). Todas a variáveis operacionais foram avaliadas em três diferentes níveis. Os resultados obtidos indicam que o leito fluidizado pulsado-rotativo é um equipamento adequado ao processo de recobrimento de microgrânulos, para as condições avaliadas, com grandes vantagens em relação ao equipamento de leito fluidizado convencional, destacando-se a redução na formação de aglomerados / Abstract: The coating process of microgranules in a Rotative-Pulsed Fluidized Bed was investigated through the accomplishment of microcrystalline cellulose (MICROCEL) coating experiments. The influence of particle load, gaseous stream pulsation frequency, suspension flow rate, pressure of atomization and drying temperature on the coating efficiency, relative growth and agglomeration index were analyzed and argued. The main objective of this work development was the evaluation of the performance and the behavior of microgranule coating process in fluidized bed equipment with beaten feeding of the gaseous stream, front a conventional fluidized bed equipment, which behavior is widely described in literature. For the inquiry of the coating process, a polymeric suspension of EudragitÒ and MICROCEL particles with diameter range of 0.25 ¿ 0.42 mm were used. The average relative growth of particles was of 3.63 %. The experiments were carried out according experimental planning techniques, where the obtained experimental results analyses had been carried through the Response Surface Methodology. The analysis of the effect of the independent variable on the process answer variables had been used in the construction of an empirical model, aiming to predict the process behavior, when possible. The analysis of the obtained models was carried out using the variance analysis (ANOVA). The independent variable used had been: suspension flow rate (Ws), atomization pressure (Pat), air temperature (Tar), bed particle load (m) and pulsation frequency (f). Results obtained shown that Rotative-Pulsed Fluidized Bed is an adequate equipment to be used in microgranules coating process in the evaluated operational conditions showing great advantages when compared to conventional fluidized bed, highlighting the agglomerate formation reduction / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

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