Improving the flame retardancy and accelerating the degradation of poly (lactic acid) in soil by introducing fully bio-based additives

In this study, a novel bio-based flame retardant LC-PA is prepared by the Mannich reaction between phytic acid (PA) and L-citrulline (LC). LC-PA is combined with tannic acid (TA) and introduced into PLA to improve fire performance and accelerate biodegradability. Compared with control PLA, the PLA composite containing 10% LC-PA/TA increases the LOI value to 26.9%, reaches a V-0 rating in the UL-94 test, and reduces the peak heat release rate and total heat release by 24.5% and 21.1%, respectively. More importantly, the introduction of LC-PA/TA accelerates the degradation rate of PLA in soil, which is of significance for biodegradable materials. The addition of LC-PA/TA can attract water and provide a suitable energy source for microbial proliferation, accelerating the hydrolysis and microbial degradation of PLA. This work provides a practical approach for high flame retardancy and rapid biodegradability in the soil to the bio-based polymer.