Marie-Odile Augé, Centrale Lille France
A self-polymerising commercial additive was compounded into poly lactic acid (PLA) using a twin-screw extruder operating at 185°C. The flame retardant was is able to polymerise under heating. Screw compounding of 20% loading of the FR into the PLA resulted in a c. 10% reduction in peak heat release (cone calorimeter), whereas the reduction in peak heat release rate increased to -43% when the compound was cured at 150°C for 80 minutes (-36% when cured for 120 minutes). The addition of the PIN FR and the curing had little effect on the transition (melt) temperatures of the PLA. The authors conclude that the fire protection effect is a combined result of increased char generation and gas phase action.