Manufacturing and mechanical characterisation of polypropylene/elium composites

• Main Author: Lim, Adrian Chee Yean
• Other Authors: Leong Kah Fai
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Materials::Composite materials; Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/149236
• Institution: Nanyang Technological University

Innegra™ is a thermoplastic fibre made from polyolefin polypropylene used in the manufacturing of composites. Innegra™ is extremely lightweight and possesses good impact resistance as well as vibration damping properties. Innegra’s unique characteristics provides a new avenue of development for fibre reinforced polymer composites. Poly(methyl methacrylate) (PMMA) resin, also known as Elium®, is a liquid thermoplastic resin with similar mechanical properties to that of thermosetting using epoxy. This final year project seeks to compare and understand the mechanical properties between different composite systems consisting of Innegra™ /epoxy (PPEP) and Innegra™ / Elium® (PPEL). Laminate samples are made for each composite system to characterize their properties using six different mechanical characterisation tests: flexure test, tensile test, impact test, mode I fracture toughness test, dynamic mechanical analysis (DMA) test and vibration test. The test results are then analysed to understand the failure mechanics of Innegra™ /epoxy and Innegra/Elium® composites. The mechanical characterisation of PPEL composites is significant as combining Innegra™ and Elium® as a composite could potentially lead to the development of a composite system with exceptional impact resistance and damping properties, which could be used in applications where high impact and vibration damping is needed, such as sporting goods like bike helmets, bike frames, tennis rackets and for automotive, military/protective and other industrial applications. It was found that PPEL composites exhibited similar maximum tensile stress and flexural modulus compared to PPEP composites when tested in tension and flexure respectively. However, PPEL composites exhibited 14.3% higher tensile strain and 14.2% higher flexural strength compared to PPEP composites. PPEP composites were found to have 13% higher mode I fracture toughness compared to PPEL composites. When tested under impact, PPEL composites exhibited lower peak force values and higher absorbed energy at higher impact energies compared to PPEP composites. The damping properties of PPEL were found to be higher than PPEP composites through mode I fracture toughness and vibration tests, with a 20% higher structural damping capability compared to PPEP composites obtained from the vibration test. Microstructural observation of failed tensile, flexure and mode I fracture toughness test specimens showed more plastic deformation of the matrix in PPEL composites compared to PPEP due to Elium®’s more viscoelastic nature.