Fibre orientation of novel dynamically sheet formed discontinuous natural fibre PLA composites

This paper describes work carried out to fabricate and to assess the fibre orientation in PLA reinforced by aligned discontinuous harakeke and hemp fibre mats produced using a dynamic sheet former (DSF). These mats were combined with PLA sheets to make composites with fibre contents of 5-40 wt% using a hot press. It was found that the fibre orientation factors (Kθ) for both harakeke and hemp fibre composites were higher than those values seen in the literature for composites prepared using injection moulding and hot pressed using randomly oriented fibre mats, but slightly lower than the highest values obtained with aligned fibre nonwoven preform composites utilising more processing stages. The highest Kθ values for harakeke and hemp fibres in this work were found to be 0.58 and 0.44 respectively. Kθ decreased, reflecting increased fibre misalignment as fibre content increased, believed to be due to fibre agglomeration and the higher pressure required during processing.