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Abstract(s)
O presente trabalho teve como principal objetivo o estudo de estruturas têxteis de reforço de base natural visando o desenvolvimento de bioprepregs, através da sua combinação com uma matriz polimérica, ambos com origem biológica. O biocompósito produzido tem como finalidade a aplicação no setor automóvel. A indústria automóvel apresentou um rápido crescimento ao longo dos anos, promovendo a procura por técnicas
de fabrico e materiais mais sustentáveis para produção de materiais compósitos de alto desempenho. A utilização de fibras naturais como estrutura de reforço de materiais préimpregnados tem sido estudada como alternativa às fibras sintéticas mais usadas, apresentando um impacto ambiental reduzido e boa performance mecânica. Neste contexto, para a produção de estruturas pré-impregnadas, os materiais alvos de
estudo foram um tecido 100 % natural, de fibras de cânhamo, e duas matrizes poliméricas: poliamida 11 e polihidroxibutirato. A junção da matriz polimérica com a estrutura de reforço foi realizada por termoconformação. Primeiramente foram testadas diferentes condições de prensagem, nomeadamente temperatura, pressão e tempo de prensagem. Validadas as condições adequadas, avaliou-se o desempenho dos bioprepregs produzidos com diferentes quantidades de polímero adicionado. Por fim, procedeu-se à produção compósita e posterior testagem de desempenho. Ao longo deste estudo foram utilizadas diversas técnicas: DSC, miscroscopia digital, FTIR, medição de porosidade, SEM, resistência mecânica à tração, avaliação da flamabilidade, da solidez à luz e teste ao odor. Relativamente a resultados, as condições de prensagem validadas para o uso da matriz polimérica de poliamida 11 foram 195 ºC, 90 kN e 4 minutos de prensagem, enquanto para a matriz polimérica de polihidroxibutirato foram de 170 ºC, 30 kN e 2 minutos. Para
ambas as matrizes, verificou-se que 50 % de polímero seria a quantidade ideal para a produção de pré-impregnados. Por fim, foi produzido um compósito resultante da agregação de prepregs, obtendo-se um compósito final com as características adequadas à sua aplicação no setor automóvel.
The main objective of this work was to study natural-based textile reinforcement structures for the development of bioprepregs, through their combination with a polymer matrix, both of biological origin. The produced biocomposite is intended for application in the automotive sector. The automotive industry has experienced rapid growth over the years, promoting the search for more sustainable manufacturing techniques and materials to produce high-performance composites. The use of natural fibers as a reinforcement structure for prepregs materials has been studied as an alternative to the most used synthetic fibers, with a reduced environmental impact and good mechanical performance. In this context, to produce prepreg structures, the materials studied were a 100 % natural hemp fiber fabric and two polymeric matrices: polyamide 11 and polyhydroxybutyrate. The combination of the polymer matrix with the reinforcement structure was carried out through the thermoforming technique. Initially, different pressing conditions were tested, namely temperature, pressure and pressing time. Once the appropriate conditions had been validated, the performance of the bioprepregs produced with different amounts of added polymer was evaluated. Finally, the composite was produced and its performance tested. Many techniques were used throughout this study: DSC, digital miscroscopy, FTIR, porosity analysis, SEM, mechanical testing, flammability testing, lightfastness and odor testing. About the results, the validated pressing conditions for the use of the polyamide 11 polymer matrix were 195 ºC, 90 kN and 4 minutes of pressing, while for polyhydroxybutyrate polymer matrix they were 170 ºC, 30 kN and 2 minutes. For both matrices, it was found that 50 % polymer was the ideal amount to produce prepregs. Finally, composite production was achieved, from the aggregation of prepregs, yielding a final composite with the appropriate characteristics for application in the automotive sector.
The main objective of this work was to study natural-based textile reinforcement structures for the development of bioprepregs, through their combination with a polymer matrix, both of biological origin. The produced biocomposite is intended for application in the automotive sector. The automotive industry has experienced rapid growth over the years, promoting the search for more sustainable manufacturing techniques and materials to produce high-performance composites. The use of natural fibers as a reinforcement structure for prepregs materials has been studied as an alternative to the most used synthetic fibers, with a reduced environmental impact and good mechanical performance. In this context, to produce prepreg structures, the materials studied were a 100 % natural hemp fiber fabric and two polymeric matrices: polyamide 11 and polyhydroxybutyrate. The combination of the polymer matrix with the reinforcement structure was carried out through the thermoforming technique. Initially, different pressing conditions were tested, namely temperature, pressure and pressing time. Once the appropriate conditions had been validated, the performance of the bioprepregs produced with different amounts of added polymer was evaluated. Finally, the composite was produced and its performance tested. Many techniques were used throughout this study: DSC, digital miscroscopy, FTIR, porosity analysis, SEM, mechanical testing, flammability testing, lightfastness and odor testing. About the results, the validated pressing conditions for the use of the polyamide 11 polymer matrix were 195 ºC, 90 kN and 4 minutes of pressing, while for polyhydroxybutyrate polymer matrix they were 170 ºC, 30 kN and 2 minutes. For both matrices, it was found that 50 % polymer was the ideal amount to produce prepregs. Finally, composite production was achieved, from the aggregation of prepregs, yielding a final composite with the appropriate characteristics for application in the automotive sector.
Description
Esta Dissertação de Mestrado foi realizada no âmbito do Projeto Integrado be@t –Bioeconomia Têxtil, para Reforço da Bioeconomia Nacional, financiado pelo Fundo Ambiental através da Componente 12 – Promoção da Bioeconomia Sustentável (Investimento TC-C12-I01 – Bioeconomia Sustentável N.º 02/C12-i01.01/2022), dos fundos europeus atribuídos a Portugal pelo Plano de Recuperação e Resiliência (PRR), no âmbito do Mecanismo de Recuperação e Resiliência da União Europeia (UE), enquadrado no Next Generation EU, para o período de 2021-2026.
Keywords
Natural fibers Polymer matrix Bioprepregs Biocomposites Fibras naturais Matriz polimérica Biocompósitos