Preparation and characterisation of a triazine structure charring agent and its application in polypropylene

A triazine long chain charring agent (TCA) was synthesised using cyanuric chloride, morpholine and anhydrous piperazine.  The synthesised TCA was compounded with ammonium polyphosphate (APP) to obtain an intumescent flame retardant (IFR). When the TCA content in the IFR was 35 wt% to 45 wt%, the IFR had good expansion properties. Then, different proportions of IFR were incorporated into polypropylene (PP) to prepare flame retardant PP composites, and the flame retardancy, thermal degradation behaviour and flammability behaviour for PP composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test. When 20 wt% of IFR (With TCA 35 wt%) were added into the PP matrix, the composite achieved a V-0 rating for the UL-94 test and its LOI value was increased to 28.8%. Compared with neat PP, peak heat release rate (PHRR) and total heat release (THR) decreased from 827.30(KW·m−2) and 120.48(MJ·m−2) to 210.50(KW·m−2) and 75.08(MJ·m−2).