Sustainable PLA/EFB Biocomposites Advanced with Green Plasticisers Enhancing Mechanical and Structural Integrity

Polylactic acid (PLA), a widely used biodegradable thermoplastic polymer, offers high stiffness but suffers from inherent limitations such as brittleness, low impact resistance, and poor thermal stability, restricting its deployment for use in structural and dynamic load applications. Empty fruit bunch (EFB) fibres are used as natural reinforcements due to their high cellulose content and stability. However, the hydrophilic nature of EFB and the stiffness of PLA frequently result in poor interfacial bonding and low tensile strength. To address these shortcomings, plasticisers, including xylitol (XY), sorbitol (SORB), and propylene glycol (PG), are incorporated in the PLA/EFB matrix, which can improve the resistance to impact, elongation, and tensile strength. This study aims to investigate the synergistic effects of XY, SORB, and PG plasticisers on the strength and structure of PLA/EFB composites, including tensile (ASTM D638), flexural (ASTM D790), and Shore D hardness (ASTM D2240) testing performance, alongside morphological analysis using scanning electron microscopy (SEM). Fifteen PLA/EFB composite formulations (PLA 55-70 wt%, EFB 30-40 wt%) with various plasticisers (XY, SORB, PG) at 5-15 wt% were tested to evaluate their effect on mechanical properties. Blend 12, PLA/EFB/XY/SORB (60:30:5:5 wt%) composite proved to be the most effective, with tensile strength of 25.852 MPa, flexural strength of 2.871 MPa, and Shore D hardness of 74.8. SEM morphology verified improved fibre dispersion and matrix adherence. These biocomposites exhibit potential for applications in pipeline coatings, agricultural films, car interiors, and eco-friendly packaging.