Influence of coir, fique, and sisal fibers on the environmental stability of PLA biocomposites

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Understanding the environmental degradation of biodegradable polymers is essential for expanding their use in sustainable materials applications. This study examines the degradation behavior of polylactic acid (PLA)-based composites reinforced with 5 wt% natural fibers—fique, sisal, and coir—under simulated environmental conditions, including water immersion, industrial composting, and ultraviolet (UV) exposure. The composites were produced via melt mixing and compression molding. Water absorption tests showed that although the incorporation of natural fibers increased moisture uptake compared to neat PLA, the composites retained competitive mechanical properties relative to other bio-based polymers. Under industrial composting conditions, all materials exhibited substantial disintegration, with neat PLA undergoing faster mass loss than the composites. This was attributed to the nucleating effect of the fibers, which enhanced PLA crystallinity and consequently slowed hydrolytic degradation. UV exposure results revealed that fique and sisal fibers improved the UV resistance of PLA by limiting carbonyl group formation and preserving mechanical integrity, while coir fibers offered less protection, likely due to their higher lignin content. Overall, these findings suggest that PLA composites reinforced with fique, sisal, and coir fibers exhibit favorable environmental degradation profiles, presenting a promising alternative to petroleum-derived and commercial bio-based polymers in applications where controlled degradation is desired. These results contribute to the understanding of how different natural fibers influence the environmental stability of PLA-based biocomposites under multiple degradation mechanisms.