Wear resistance of injection moulded PLA-talc engineered bio-composites: Effect of material design, thermal history and shear stresses during melt processing

PLA/Talc bio-composites are very promising materials for the fabrication of food and drug containers, packaging items, medical devices, consumer electronics as well as car components. In this work, wear resistance of PLA/talc bio-composites was investigated. Different types of formulations were analysed and, in particular, different compatibilization strategies of the hydrophilic talc with the hydrophobic PLA were studied. Specifically, micro-lamellar talc was pre-treated by 3-aminopropyltriethoxysilane (Ameo), (3-glycidoxypropyl)trimethoxysilane (Glymo), and commercially available tri-isocyanates, namely, Bayhydur 3100 and Desmodur 3900 featuring respectively hydrophilic and hydrophobic behaviour, to increase affinity with PLA. Similarly, long-range dispersing agents, namely MA (Maleic Anhydride) and GMA (Glycidyl Methacrylate) – modified PLA, were reactively extruded together with the PLA to improve compatibility with talc. The resulting formulations were found to be very easy to process and they were injection moulded to get flat substrates. Wear resistance of the injection moulded substrates were examined against a spherical steel counterpart by dry-sliding linear reciprocating tribological tests. The tribological tests were performed along two sliding directions oriented parallel and normal (anti-parallel) with respect to the flow lines of the injection moulded substrates. The bio-composites exhibited anisotropic wear response along the two sliding directions, with the compatibilization strategy playing a pivotal role.