Multi jet fusion printing of polyimide fibre-reinforced polyamide 12 composites

• Main Author: Lim, Hao Wen
• Other Authors: Zhou Kun
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Manufacturing; Engineering::Materials::Composite materials
• Online Access: https://hdl.handle.net/10356/168359
• Institution: Nanyang Technological University

With the ever-growing popularity of additive manufacturing (AM) and its technological advancements, more industries are trying to implement this technology into their business. AM not only grants industries quick and fast prototyping, with the promising development of material options, AM is also potentially used commercially in the Aerospace and Automotive industry. Among the existing methods of AM, Multi- jet Fusion printing (MJF) is a fast-growing technique that offers high production speeds and low production costs. To address the market demand for MJF-printed parts with high mechanical strength in various industries, this final year project study developed a new type of short-chopped polyimide fibre (PI) reinforced polyamide (PA) 12 composites for the first time and demonstrated the largely enhanced mechanical performance of MJF-printed PI/PA12 composite parts. The effects of the MJF printing parameters, the PI fibre concentration, and the post-annealing process effects on the fracture morphology, mechanical properties and crystallization behaviours of the PA12 matrix were systematically investigated. It was demonstrated that the MJF-printed PI/PA12 composite parts exhibited significant improvements in both tensile and flexural performance simultaneously. After a post- annealing process, the mechanical properties of the composite parts were further improved. Specifically, the tensile strength and modulus were increased by 43% and 42%, and the flexural strength and modulus were increased by 39% and 46%, compared to the neat PA12 parts. Meanwhile, the inclusion of the lightweight PI fibres endowed the PI/PA12 composites with an ultra-high specific tensile strength of 67.6 I kN·m/kg and specific flexural strength of 93.7 kN·m/kg, which were superior to most fibre-reinforced PA12 composites printed by MJF. The newly developed PI/PA12 composites will expand the library of high- performance powder feedstocks suitable for MJF and thereby broaden the application space of MJF in fields requiring high-performance materials. Beyond MJF, this work also provides new insights into enhancing the mechanical properties of parts printed by other powder bed fusion techniques.