Research Of Halogen-free Flame Retardant Epoxy Resin Syestem

Recently,with the enhancement of environmental awareness and development of transportation,materials face more and more new challenges of lightweight and lowcost.Hence,the epoxy resin composites have increasingly highlighted their unique advantages.Applications of the composites in high-speed rail are seriously restricted by poor flame retardation and high smoke density,although widely used in civil field due to excellent mechanical properties,chemical stability,lowcost,etc.In view of these problems,the flame retardant mechanism of epoxy resin,the key factors affecting the flame retardant performance and the performance of composites are studied in this paper,which will provide a material and technical support for Chinese high-speed rail.Firstly,synthetically considering flame retardant,latent,mechanical,processing properties and so on,the resin system,which includes silicon,phosphorus and nitrogen synergistic flame retardant,dicyandiamide and UR500 for latent curing system,is determined by oxygen index,processing properties,DSC and so on.The results show that the prepreg of 610 BE which has excellent mechanical properties,storge and flame retardant fully meet up with the technological requirements of out of autoclave.Secondly,the core of the flame retardant is a novel reactive phosphorus-silicone and the low viscosity liquid flame retardant improve the processing property of the system,synergistically intensifying the property of the flame retardant.The resin syetem includes a low viscosity bisphenol-F-epoxy resin,curing system DETDA and reactive diluents of epoxy resin.Synthetically considering the flame retardancy,processing and thermal properties of the system,a high-efficiency flame retardant epoxy resin R610 is processed.The results reveal that the composites processed by VARI is compared with the composites of 610 B.Finally,the influence of different ratardants on the flame retardant properties of the epoxy resin,such as the properties of flame retardant,self-extinguish away from the fire,and smoke densityisexplored by the limit oxygen index,vertical combustion and smoke density.The mechanism of flame retardant is studied by the carbonization capacity,carbon microstructure of the resin after burning by SEM or TGA and Flynn-Wall-Ozawa to explore the activation energy in the process of combustion.The results reveal that the improvement of the flame resistance,self-extinguish away from the fire is mainly duing to earlier and faster carbonizing and the smoke density decreases for gradient-distribution micropores on the carbon layer.The micropores is not only beneficial tosufficient combustion of decomposition compents but also further to inhibiting decomposition of lining materials,so as to suppress smoke.And the results are certified by that the activation energy of the excellent flame retardant system rapidly rises from the low,and stabilizes on the highest place.