RDP and APP/MC/PPO compound intumescent flame retardant of polyethylene

Poly ammonium polyphosphate (APP), melamine cyanurate (MC) and polyphenylene oxide (PPO) were combined to prepare intumescent flame retardant (IFR) for polyethylene (PE) by adding the synergistic agent resorcinol bis-(diphenyl phosphate) (RDP). The limiting oxygen index (LOI) and vertical burning test were used to study the synergistic effects between IFR and RDP, the effect of add amount of RDP to the combustion performance, and mechanical property of the composite flame retardant IFR. The thermal analysis methods of TG and DTG were used to test and verify the synergistic effect. The results show that there are synergistic effect between RDP and IFR, and the effective synergistic effect of RDP mainly in the first stage of thermal decomposition. The RDP catalyzes the decomposition of APP earlier and decreases the heat release, promotes the formation of carbon layer, and improves the carbon residue significantly during the process of thermal decomposition. When the amount of RDP is 5% (mass fraction), the LOI reaches the maximum value of 31, and passes the criterion UL94 V-0. Obviously, the combination of RDP and APP/MC/PPO can significantly improve the inflaming retarding properties of PE.