PINEAPPLE LEAF FIBRE/POLY (3-HYDROXYBUTYRATE-CO-3-HYDROXY VALERATE) DEGRADABLE COMPOSITE: MORPHOLOGY AND FAILURE PREDICTION OF MECHANICAL STRENGTH USING WEIBULL ANALYSIS

Abstract

This study investigates the mechanical properties and failure behaviour of biodegradable composites made with pineapple leaf fibre (PALF) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as the matrix. The study focuses on the effect of varying fibre loadings and their failure behaviour. The PALF was treated with a 5% NaOH solution, and the PALF/PHBV composites were prepared using solvent casting, followed by compression moulding. Flexural tests showed that increasing PALF content significantly improves both flexural strength and modulus, with the highest values observed at 40 wt.% PALF, reaching 108.36 (±8.53) MPa and 6.39 (± 0.71), respectively. Morphology analysis through scanning electron microscopy (SEM) revealed better stress transfer and fibre-matrix adhesion at higher loadings, although some fibre pull-out and debonding were observed. Statistical analysis using a two-parameter Weibull distribution demonstrates that higher fibre content enhances mechanical strength and has a lower Weibull modulus than neat PHBV. This indicates greater variability of the composite strength, possibly caused by uneven stress distribution and poor matrix/fibre interface bonding. The study concludes that optimising fibre content is crucial for maximising the mechanical performance of PALF/PHBV composites. These findings contribute to the advancement of sustainable materials, highlighting the potential of the materials in developing high-performance bio-composites where sustainability, strength, and biodegradability are important considerations, such as automotive components, construction materials, agriculture and others.