Effect of Compatibilizers on the Physico-mechanical Properties of a Poly(Lactic Acid)/ Poly(Butylene Adipate-co-terephthalate) Matrix with Rice Straw Micro-particle Fillers

This study explores the blending of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with rice straw micro-particles (10 to 30 wt%, ≤ 250 μm) to create biocomposites using a kinetic mixer. It examines the effects of chain extender (J) and maleic anhydride (MA) as compatibilizers on material properties. Biocomposites underwent 500 h accelerated weathering to simulate environmental conditions, with analysis via Fourier-transform infrared spectroscopy (FTIR), mechanical testing, dynamic mechanical analyses (DMA), and rheological evaluations. Results indicate that the chain extender’s superior performance over MA, generating 6% insoluble content compared to 1% with MA. Scanning electron microscopy (SEM) revealed reduced interfacial voids in biocomposites treated with compatibilizers. The addition of the rice straw was found to increase the tensile modulus from 2.3 to 3.4 indicating a 43% increase after 40 wt% rice particles; all the while reducing the tensile strength and ductility. Post-weathering, Joncryl® treated samples retained properties better than MA-treated ones, showing enhanced crosslinking and less decline in tensile strength (10–19% reduction for J vs. 27–30% for MA). Compatibilizers, especially the chain extender, play a crucial role in strengthening PLA and PBAT biocomposites, particularly under accelerated weathering.