Optimisation of the twin-screw compounding process for short fibre biocomposites

Short plant fibre reinforced thermoplastic composites are rapidly emerging as a sustainable material alternative for filled and unfilled thermoplastics as well as a wood replacement. Twinscrew extrusion is one of the key processes used both in the compounding stage and in the production stage for this family of bio-composites. Despite the importance of the twin-screw extruder in the processing of plant fibre composites, the majority of research effort in this field has been focused on fibre treatment processes and property characterisation whereas the actual extrusion process has received little attention. Understanding the twin-screw compounding process is one of key steps on the route to a commercial plant fibre reinforced thermoplastic composite. As part of CRC-ACS Project P1.1 “Plant fibre bio-composites”, the twin-screw compounding process has been studied from various angles and key aspects such as the effects of feeding location, screw configuration and feeding strategies have been investigated. This paper summarises the key findings from this research and explains how the results can be used in the production of cost competitive, sustainable short plant fibre thermoplastic composites