Simultaneously enhance both the flame retardancy and toughness of polylactic acid by the cooperation of intumescent flame retardant and bio-based unsaturated polyester

Despite the excellent biodegradable and competitive comprehensive properties, the application of bio-based polylactic acid (PLA) lags far behind due to the defects of inherent flammability and brittleness, which are difficult to overcome simultaneously. In this work, the reactive blending of PLA and flexible biobased unsaturated polyester (BUP) enhances the toughness of PLA, and improves the melt viscosity of PLA matrix, which is conducive for intumescent flame retardant (IFR) to play its role, so PLA with excellent toughness and flame retardancy has obtained. Adding only 11.5 wt% IFR, PLA toughen by BUP (TPLA) shows extraordinary comprehensive performance: LOI value increases to 28%, UL-94 vertical test passes V-0 rate; while, the elongation at break and notched impact strength reach 153.2% and 173 kJ/m(2), which are 17.9 times and 10.3 times of pure PLA, respectively. Further, the cone calorimeter test results demonstrate that the fire safety of TPLA/IFR has been great enhanced. This PLA material with excellent fire safety and toughness will show great application potential in the future. (C) 2019 Elsevier Ltd. All rights reserved.