A new strategy to prepare fully bio-based poly(lactic acid) composite with high flame retardancy, UV resistance, and rapid degradation in soil

Despite the advantages of biological compatibility and high transparency, there are still some drawbacks for Poly(lactic acid) (PLA) such as highly flammability and poor ultraviolet resistance. Herein, a fully bio-based additive (PA@CHTM) with a core–shell structure is synthesized by chitosan microspheres and phytic acids. The introduction of PA@CHTM simultaneously improves the mechanical properties, flame retardancy, and UV-blocking performance of PLA, accompanied by an accelerated degradation capacity in soil. By the presence of 9 wt% PA@CHTM in the PLA composite sample, the limiting oxygen index value is increased from 18.2% to 29.6%, and the UL-94 test grade is improved to V-0. The tensile strength is well maintained and Young's modulus is sharply increased for PLA/PA@CHTM composites. Moreover, the photoaging process of PLA can be significantly delayed due to the excellent free radical quenching capacity of PA@CHTM. Only less than 10% UV light can be penetrated for the PLA/9%PA@CHTM sample, and the ultraviolet protection factor is increased from 0.77 of control PLA to 30.07. More importantly, the addition of PA@CHTM can accelerate the degradation of PLA, which is of significance for biodegradable materials. This work firstly provides a green strategy to fabricate fully bio-based polymer composites with high performance, long service life, and rapid degradation in soil.