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Abstract(s)
Os materiais compósitos de matriz termoplástica vêm criar novos desafios de engenharia ao nível dos processos de fabrico quando comparados com os de matriz termoendurecível. Pelas suas propriedades mecânicas, tempos de ciclo e por questões ambientais torna-se útil estudar e evoluir o universo dos compósitos na direção dos termoplásticos. A evolução da utilização destes materiais na última década tem sido notória, fruto do conhecimento e investigação que tem vindo a ser realizada. A elevada viscosidade dos termoplásticos quando comparados com os termoendurecíveis traz novos desafios ao nível do fabrico, pela dificuldade de impregnação das fibras pela matriz. Com a evolução da tecnologia e conhecimento dos materiais vão-se implementando melhorias de forma a viabilizar a utilização destes compósitos. Nesta dissertação produziu-se pré-impregnados de matriz termoplástica por um processo inovador de deposição de polímero em pó sobre as fibras, que dá origem ao towpreg. Seguidamente transformou-se o towpreg pelo processo de pultrusão dando origem a perfis em compósito de matriz termoplástica, e estudou-se os efeitos da transformação por compressão a quente nesses mesmos perfis. Os perfis compósitos fabricados por pultrusão e compressão a quente foram sujeitos a ensaios de calcinação, flexão e corte interlaminar para conhecer os teores de fibra e a qualidade da consolidação. Pelos resultados obtidos tornou-se notório que por compressão a quente existia uma melhoria significativa da consolidação, especialmente por ser possível diminuir o teor em vazios. De forma a aumentar a produtividade no fabrico destes compósitos, trabalhou-se com fibras de elevado Tex e velocidades elevadas no processo de pultrusão.
The use of thermoplastic matrix composites creates new engineering challenges concerning the manufacturing process when compared with the thermoset composites. Due to its mechanical proprieties, cycle of manufacture times and environmental issues, it becomes useful to study and evolve the universe of composites in the direction of thermoplastics. In the last decade, the evolution regarding the use of these materials has been notorious due to the knowledge and investigation that has been carried out. The high viscosity of the thermoplastics when compared with the thermoset polymers, brings new challenges in the processing of composites, especially in the process of impregnating the fibers in the matrix. With the evolution of technology and knowledge, improvements have been implemented to make feasible the use of these composites. In this dissertation, thermoplastic matrix prepregs were produced by a ground-breaking process of powder deposition in fibers, which created towpreg. The towpreg was then transformed by pultrusion, resulting in a thermoplastic matrix composite profile, then those profiles were transformed by hot compression moulding and the effects of these processes were studied. The composites manufactured by pultrusion and compression moulding were then tested with a series of calcination, bending and interlaminar tests to know the fibre content and the quality of consolidation. From the results obtained, it became apparent that by hot compression moulding there was significant improvement of the consolidation, especially since it is possible to decrease the void content. To increase the rate of production of these composites, we worked with high Tex fibres and higher speeds in pultrusion process.
The use of thermoplastic matrix composites creates new engineering challenges concerning the manufacturing process when compared with the thermoset composites. Due to its mechanical proprieties, cycle of manufacture times and environmental issues, it becomes useful to study and evolve the universe of composites in the direction of thermoplastics. In the last decade, the evolution regarding the use of these materials has been notorious due to the knowledge and investigation that has been carried out. The high viscosity of the thermoplastics when compared with the thermoset polymers, brings new challenges in the processing of composites, especially in the process of impregnating the fibers in the matrix. With the evolution of technology and knowledge, improvements have been implemented to make feasible the use of these composites. In this dissertation, thermoplastic matrix prepregs were produced by a ground-breaking process of powder deposition in fibers, which created towpreg. The towpreg was then transformed by pultrusion, resulting in a thermoplastic matrix composite profile, then those profiles were transformed by hot compression moulding and the effects of these processes were studied. The composites manufactured by pultrusion and compression moulding were then tested with a series of calcination, bending and interlaminar tests to know the fibre content and the quality of consolidation. From the results obtained, it became apparent that by hot compression moulding there was significant improvement of the consolidation, especially since it is possible to decrease the void content. To increase the rate of production of these composites, we worked with high Tex fibres and higher speeds in pultrusion process.
Description
Keywords
Materiais Compósitos Matriz Termoplástica Fibra de Carbono Polipropileno Préimpregnado Pultrusão Compressão a quente Perfil Compósito Laminado Compósito Termoplástico Composite Materials Thermoplastic Matrix Carbon Fibre Fibre Polypropylene Prepreg Pultrusion Hot Compression Moulding Composite Profile Thermoplastic Composite Laminate