Synergy between the aluminum diethyl hypophosphite (ADP) and melamine cyanurate (MCA) in stereo-complex type polylactic acid simultaneously towards fire retardancy and heat resistant properties

Developing fire retarded and heat resistant Polylactic Acid (PLA) is a challenging task owing to its high flammability, melt-dripping and low heat distortion temperature. In this work, based on the synergy between aluminum diethyl hypophosphite (ADP) and melamine cyanurate (MCA), a promising intumescent PLA with enhanced fire retardancy and heat resistant properties was obtained. The results showed that the PLA/15ADP/15MCA sample passed the UL-94 V-0 rating with anti-dripping performance and reached 33% in LOI. Besides, simultaneous addition of MCA and ADP can effectively inhibit the formation of HC crystals, promote the formation of SC crystals (55.23%), improve the crystallization rate and thus, significantly improve the heat resistance PLLA/PDLA/MCA15/ADP15 sample. Its heat distortion temperature (HDT) can reach 209.8 °C, which increased by 96.3 °C. In perspective, this work opens a new window in simultaneously improve the fire retardancy and heat resistance of PLA, which can highly expand its application.