Engineering the Degradation Profile and Mechanical Performance of Polyethylene Fibers via Polylactic Acid Blending

Abstract

This study investigates the structure-property-degradation relationships of melt-spun polyethylene/polylactic acid (PE/PLA) blend-fibers, addressing the knowledge gap regarding the biodegradation mechanisms of oriented fiber morphologies compared with bulk films. PE/PLA fibers with varying compositions (5–50 wt% PLA) were fabricated via melt spinning and subjected to controlled soil burial degradation (ISO 17556:2019) for 85 days. The results reveal a composition-dependent, three-stage biodegradation mechanism characterized by selective PLA hydrolysis, fungal hyphae penetration at phase boundaries, and subsequent structural fragmentation. Mechanical characterization identifies the 90/10 PE/PLA blend as the optimal formulation, achieving a tensile strength of 64.88 ± 3.1 cN/Tex, which exceeds that of pure PE. This enhancement is attributed to effective stress transfer facilitated by weak interfacial dipole – induced dipole interactions and van der Waals forces, evidenced by a 6 cm−1 redshift in carbonyl stretching vibrations observed by FTIR and an interfacial bonding energy (ΔG) of 12.6 kJ/mol. In contrast, blends containing higher PLA contents (≥20 wt%) exhibit pronounced phase separation accompanied by a significant reduction in elastic-modulus, decreasing from 294.3 to 73.28 cN/Tex. Furthermore, degradation kinetics analysis demonstrates that fibers with 40 wt% PLA degrade approximately four times faster than pure PE, corresponding to 12.3 versus 3.2% weight loss.