Toward a new approach to synchronously improve the fire performance and toughness of polylactic acid by the incorporation of facilely synthesized ammonium polyphosphate derivatives

Polylactic acid (PLA) with eco-friendliness exhibits extensive potential applications. In order to enhance fire-resistance of PLA, this manuscript reports the preparation of boron-containing ammonium polyphosphate (B-APP) using 3-aminophenyl boronic acid and ammonium polyphosphate through ion exchange reaction , and incorporated into PLA matrix. The limiting oxygen index (LOI) of PLA-5% B-APP was increased from 19.2% to 29.4% and a UL-94 V-0 rating. In the cone calorimeter tests, PLA-5% B-APP presented a total heat release (THR) reduction from 81 MJ·m −2 to 67 MJ·m −2 and an improvement from 1.6% to 6.7% in char residue comparing with PLA. The mechanism of B-APP was mainly ascribed to the formation of glassy char layers to block the heat and oxygen transfer. For mechanical properties , it could be also found that the elongation at break and impact strength were improved at the presence of 5% B-APP.