Synergistic Effects of Polysaccharide Biomass and Ammonium Polyphosphate on the Flame Retardancy of Epoxy Resin
Two kinds of biomass with polysaccharide structures,chitosan(Cs)and starch(St),were chosen as synergists to improve the flame retardancy of epoxy resin(EP)/ammonium polyphosphate(APP).The synergistic effects of polysaccharide biomass and APP on the flame retardancy of EP were studied.The flame retardancy was characterized by limiting oxygen index,vertical combustion,cone calorimetry,thermogravimetric analysis,scanning electron microscopy and Raman spectroscopy,etc.The results show that,compared with only adding the same amount of APP,the synergistic flame retardant system of polysaccharide biomass and APP has a significant flame retardant effect on EP.The synergistic flame retardancy is optimal when the mass fraction ratio of APP to chitosan or starch is 12∶2 or 13∶1.The limiting oxygen index of EP/APP is 26.7%,which reaches 28.2%for EP/APP/chitosan system and 28.4%for EP/APP/starch system.Combustion grades increases from HB grade to V-0 grade.At the same time,the peak of heat release rate and total heat release are significantly reduced.CO and CO2 emissions are significantly reduced.The amounts of residual chars increase significantly and the residual chars are continuous,dense and high graphited.Thus,polysaccharide biomass displays a good synergistic effect with APP on the flame retardancy of EP.
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