Exploring the effect of melamine pyrophosphate and aluminum hypophosphite on flame retardant wood flour/polypropylene composites

In this examine, melamine pyrophosphate (MPP) and aluminum hypophosphite (AHP) were selected as flame retardants. The synergistic effect between the MPP and AHP on flame retardancy and thermal stability of the polypropylene (PP)/wood flour (WF) composite were investigated. The thermal stability and char forming ability were enhanced considerably for the PP/WF composite with 20 wt% MPP/AHP (3:1), which were indicated by the thermal gravimetric analysis (TG), along with reductions in the heat release rate (HRR) and the smoke production release rate (SPR). The outcomes of TG, scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed that there were inert gases as well as more phosphates and phosphoric acid formed. Which effectively diluted flammable gases and enabled more intumescent char residue to form. In summary, the system of MPP/AHP was equipped with perfect effect of gas phase and condensed phase flame retardancy, endowing PP/WF composite with outstanding capacity of inflaming retarding.