Synthesis of Polypyrrole Microcapsules Encapsulating γ-Fe2O3 and Its Application in Intumescent Flame-Retardant Systems
Intumescent flame-retardant epoxy resin(EP)composites were prepared by incorporating PPy-Fe2O3,derived from microencapsulated polypyrrole(PPy)coated with γ-Fe2O3,as co-enhancer and diamino diphenyl methane modified ammonium polyphosphate(DDP)as flame retardant.The effects of PPy-Fe2O3 on the flame retardancy,thermal stability,and carbon formation of the EP/DDP system were investigated through limiting oxygen index test(LOI),UL94,thermogravimetric analysis,cone calorimeter,and scanning electron microscope.Results demonstrate adding PPy-Fe2O3 improves the flame retardancy,smoke suppression,and thermal stability of the EP/DDP system.The combination of PPy-Fe2O3 with DDP forms a denser and more stable char layer structure,resulting in reduced heat release and smoke production.The incorporation of 0.2％PPy-Fe2O3 and 9.8％DDP in the EP composite leads to a 12.3％reduction in peak heat release rate(PHRR)and 11.0％reduction in peak smoke production rate(PSPR).Moreover,these composites achieve UL94 V-0 rating and LOI of 35.5％.TG analysis validates that the adding PPy-Fe2O3 significantly improves the thermal stability and char formation characteristics of the EP/DDP system.At 700 ℃,the EP composite containing 0.2％PPy-Fe2O3 exhibits a residual char content of 32.0％.
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