The ultra-low addition of P/Si/N-containing flame retardant towards simultaneous enhancement of flame retardancy, mechanics and degradability of PLA

This study designed and synthesized a novel phosphorus silicon synergistic flame retardant PDD. Only adding 1 wt% PDD can achieve excellent UL-94 V-0 flame-retardant rating for PLA composite, and the limit oxygen index (LOI) can be increased to 26.8 %. At the same time, the thermal stability and crystallinity of composites are significantly improved. The results of the cone calorimeter test show that compared with pure PLA, PLA/1 % PDD reduces the peak heat release rate (pHRR), total heat release (THR), and peak of CO 2 release rate (pCO 2 P) by 38.2 %, 42.9 %, and 26.6 %, respectively. It is worth noting that PDD not only enhances the tensile strength and impact toughness of PLA composites, but also accelerates their chemical degradation process in alkaline environments through ester bond hydrolysis promoted by phosphorus silicon synergy. This work has achieved a multifunctional integration of mechanical properties, efficient flame retardancy, and chemical degradation, providing new ideas for the development of multi-functional biodegradable polymers.