Simultaneously boosting the flame retardancy and degradability of poly(lactic acid) composite by phosvitin affiliation

Currently, it is still a challenge to endow polylactic acid (PLA) with excellent degradation and fire safety. In this work, we have extracted a novel phosvitin aiming to achieve the fire resistance and degradation of PLA. Employing the phosvitin, the PLA composite exhibits conspicuous fire resistance with an LOI of 27.4 % and a V-0 rating in the UL-94 tests by controlling the added volume at 40 wt.%. Simultaneously, the thermal stability and fire behaviour of the PLA composite have been improved by the plentiful char residue formation. The flame-retardant mechanism of phosvitin in PLA material has been deduced by TG-IR, FTIR XPS and SEM. The phosvitin containing abundant P-O, P = O and P-N functional groups generates phosphorus-containing compounds to promote the dehydration reaction of the PLA matrix in a condensed phase. This is beneficial to improve the flame retardancy of PLA by the formation of a char layer, providing the shielding effect to prevent the heat transfer and flammable micro-molecules volatilisation process. Likewise, the affluent phosphorus-containing compounds included in the phosvitin possess fabulous catalytic action to destroy the PLA into small molecular weight fragment which shows a beneficial to promote the degradation reaction of PLA composite. Hence, the phosvitin is important to expand the range of applications of PLA materials to develop sustainable multifunctional materials.