Poly(lactic acid)/thermoplastic polyurethane/wood flour composites: evaluation of morphology, thermal, mechanical and biodegradation properties

Abstract

This study was aimed at improving the toughness of poly(lactic acid) (PLA) without compromising its strength by developing a biodegradable composite based on PLA, Thermoplastic Polyurethane (TPU) and Wood flour (WF) particles. PLA/TPU/WF green composites with varying TPU content (0–50 wt%) were prepared on a twin screw extruder. The wood flour content was kept constant (10 wt%) for all the compositions. The addition of flexible TPU (10–50 wt% of total polymer composition) to the brittle PLA causes a significant increase in impact strength and elongation at break by ∼12.40 times and ∼3.57 times (for 50 wt% TPU content), respectively. Incorporation of WF filler brought improvement in tensile strength (∼1.47 times) and impact strength (∼871% enhancement over neat PLA) of the PLA/TPU blends with 50 wt% TPU content. Morphological analysis using SEM revealed that uniformly dispersed WF particles enhanced the interfacial interaction (H-bonding observed in FTIR spectra) between the TPU and PLA phase. Thermal analysis using DSC also shows that addition of TPU and WF depreciated the crystallinity of PLA because of enhanced interaction between the components which interferes with the crystallization of PLA. Finally, biodegradability studies (tested under soil) for 1 month demonstrated the significant degradability of PLA/TPU/WF composites in presence of WF particles. The potential applications of these bio-composites may range from automobiles, packaging to furniture industries.