Study On The Synthesis And Property Of A Silicon-containing Flame Retardant Epoxy Resin

Epoxy resin(EP) has been widely used in the fields of mechanics,electronics, aircraft and spacecraft,etc because of its outstanding properties.Halogenated epoxy resin played a very important role in the field of epoxy resin for its excellent flame retardance.However,it was discovered that the application of halogenated epoxy resin had been limited,because halogenated epoxy resin gave off toxic gases in the combustion and resulted in serious pollution to the enviornment.It's urgent to develop a novel flame retardance without halogen to satisfy the requirments of flame retardance and environmental protection.On the basis of analyzing the previous work,the synthetic route of a poly-dimethylsiloxane epoxy resin had been self designed,and poly-dimethylsiloxane epoxy resin had been synthesized.Thin-layer chromatography in the analysis has been uesd to monitoring reaction.On this basis,the crude product was seperated and purified by column chromatography.The synthetic conditions of the polydimethylsiloxane epoxy resin,such as the ratio of materials,the solvent of the reaction,the temperature of reaction,the time of reaction and so on were systematic discussed,and the best synthetic reaction conditions were obtained.Through the infrared spectrum(FT-IR),the structure of product was characterized for determining its structure.Using hydrochloric acid-acetone method,the epoxy value of poly-dimethylsiloxane epoxy resin is 0.594,and the above epoxy value corresponded with the epoxy value 0.602 which inferred from the structure of poly-dimethylsiloxane epoxy.The curing system was obtained by mixing the poly-dimethylsiloxane epoxy resin and bisphenol A epoxy resin E-44 according to a certain mass ratio,curing by diamino diphenylmethane(DDM).The curing process parameters of curing system were studied,such as the curing temperature,the ratio of curing agent and curing time.Thermal degradation behaviors and the thermo-stability of the poly-dimethylsiloxane epoxy resin/E-44/DDM curing system were investigated with the themrogravimetric analysis(TGA).It was shown that the char yield of 750℃increased under the pure nitrogen condition along with the poly-dimethylsiloxane epoxy resin proportion enhanced,and the char yield of pure poly-dimethylsiloxane epoxy resin reached 33.7,and it enhanced 69%compared to the char yield of 19.9 of pure E-44.The flame retardant property of poly-dimethylsiloxane epoxy resin/ E-44/DDM curing system was measured by the Oxygen Index(LOI) test.It was found that LOI value of the above curing system increased with the proportion of poly-dimethylsiloxane epoxy resin enhanced,and the LOI value of pure poly-dimethylsiloxane epoxy resin reached 30.2,and it enhanced 56%compared to the value of 19.3 of pure E-44.