Synergistic effects of pentaerythritol phosphate nickel salt (PPNS) with ammonium polyphosphate in flame retardant of polyethylene

摘要

Phosphorus oxychloride (POCl3), which is both hazardous and expensive, is currently employed to produce carbon agents for use in intumescent flame retardants (IFRs), thus limiting the applications of IFRs. Herein a less hazardous, more environmentally friendly POCl3-free system is described, exhibiting the same performance. A novel carbon agent synthesized through the combination of nickel carbonate with pentaerythritol phosphate nickel salt (PPNS) was applied as a flame retardant of polyethylene (PE) in conjunction with ammonium polyphosphate (APP). PE containing 32 mass% PPNS-APP passed the UL-94V-0 rating test with a value of 3.2 mm and had a limiting oxygen index (LOI) of 30 %. The LOI value increased to 34 % when 36 mass% PPNS-APP was applied. Compared with the use of APP or PPNS alone, the cone calorimeter result for PE/PPNS-APP composite was improved, while the total heat release was reduced by 46.3 and 51.9 % and the average mass loss rate was decreased by 40.6 and 87.5 %, respectively. It can be concluded that a synergistic effect between the APP and PPNS promoted the effect formation of a stable char layer in the later stages of combustion.