Effect of functionalized oyster shell powder with ammonium polyphosphate on fire safety performance of epoxy resin

In recent years, bio-based flame retardants have attracted extensive interest on account of their environmental-friendly character compared with traditional flame retardants. It is reported that oyster shell powder (OSP), composed of 95% calcium carbonate and 5 % organic matter, displays excellent flame retardant potential. In this paper, a novel bio-based flame retardant named functionalized oyster shell powder (FOSP) was prepared by mechanochemistry strategy based on OSP and ammonium polyphosphate (APP) and applied to enhance the fire safety of epoxy resin (EP) composites. The results showed that FOSP emerged with notable effects in improving the fire safety performance for EP composites. Compared with pure EP, the peak value of smoke production rate (pSPR) and peak value of heat release rate (pHRR) reduced by 69.4 % and 78.2 %, respectively. In addition, the char yields of EP composites were higher than EP. Conspicuously, the total CO production for EP composites with the addition of FOSP decreased by 44.9 % compared with EP composites with the addition of APP. Therefore, OSP, a typical marine solid waste, will become a promising candidate for high fire safety polymers.