Flame retardancy properties of ammonium polyphosphate with crystalline form II by non-P2O5 process

Abstract

Ammonium polyphosphate (APP) produced by non-P2O5 process and traditional P2O5 process were used in an intumescent flame retardant (IFR) polypropylene (PP) composition (IFR–PP). Rare earth oxide CeO2, in different amounts was added to study its synergistic effects in the IFR–PP material by limiting oxygen index (LOI), UL-94 and mechanical properties. TGA and SEM were used to study the decomposition processes of CeO2 added IFR–PP compositions, and to investigate its synergistic mechanism. Results showed that CeO2 could increase the LOI value of IFR–PP, maximum LOI values were found with certain amounts of CeO2. SEM demonstrated that CeO2 could promote formation of a homogenous and compact intumescent char layer. It was shown that APP by non-P2O5 process had similar IFR properties as APP by traditional P2O5 process.