Properties of coir fibre/polylactic acid composites based on amylase processing

Abstract

The objective of this study was to investigate the impact of amylase treatment on the properties of polylactic acid (PLA) composite, using coir fiber. The coir fiber was treated with a 5% amylase solution and the modified coir/PLA composite was produced via hot pressing. The mechanical properties, water absorption and moisture absorption properties, and microstructure of the composites were analyzed. The findings revealed that the addition of amylase-treated coir fiber significantly enhanced the strength and stiffness of the composite. Specifically, the tensile strength, bending strength, and impact strength increased by 5 times, 3.6 times, and 2 times, respectively. Furthermore, the composite’s fracture mode changed from pure tensile to shear and tensile mixed fracture. The water absorption performance of the coir fiber composite increased by an average of 29.58% after amylase treatment, which improved the composite’s ability to withstand humidity. Lastly, the microstructure of the composite material was discussed. The enzyme decomposed the starch in the fiber, removing impurities and increasing the surface area, providing more sites for binding to polylactic acid and improving the interface compatibility between the two substances. The results are significant for developing new and sustainable bio-based composites.