Improving the toughness and flame retardancy of poly (lactic acid) with phosphorus-containing core-shell particles

Despite polylactide (PLA) representing one of the most promising biodegradable materials, its applications lag far behind owing to the disadvantages of inherent brittleness and flammability, which is challengeable to simultaneously overcome. In this work, a phosphorus-containing core-shell starch nanoparticle (FR-CSS) was synthesized via soap-free emulsion polymerization for concurrent improvement of toughness and flame retardancy of PLA. The results revealed that with the incorporation of 10 wt% FR-CSS, the elongation at break of PLA/10FR-CSS was prominently improved to 308% while the tensile strength was about 40.0 MPa. Particularly, the toughness of PLA/FR-CSS was as high as 108.2 MJ/m(3), which was 48 times higher than that of neat PLA. Besides, the PLA/10FR-CSS exhibited improved flame retardancy with a UL-94 V-2 rating and a LOI value of 24.5%. These results established an integrated design strategy of incorporating phosphorus-containing core-shell nanoparticles to prepare PLA composites combined excellent toughness with enhanced flame retardancy, therefore broadening the application gallery of PLAs.