Containing P/N/B/S multi-element flame retardant epoxy resin: Low smoke, low dielectric strength, UV shielding

With the development of rail transit in the direction of high-speed and safety, the multifunctional epoxy resin (EP) featuring flame resistance, low smoke emissions, low dielectric constant and Superior UV shielding has excellent development prospects. This study introduced a multifunctional new reactive flame retardant FSD, which, by incorporating P/N/S/B, significantly modified epoxy resin and achieved multi-functional upgrading of the resin. The results showed that the limiting oxygen index (LOI) of the modified epoxy resin EP/FSD7.5 was enhanced to 33.2 %, and there was a notable enhancement in the material's fire safety, attributed to a 45.03 % reduction in the peak heat release rate (PHRR) and a 44 % decrease in total smoke production (TSP). In addition, the introduction of FSD gave EP excellent UV shielding properties and optimized its dielectric properties without sacrificing mechanical properties. In particular, in the smoke density test, the specific optical density of the fourth minute (D_S (4)) and Cumulative smoke concentration in the first four minutes (VOF₄) values for the EP/FSD7.5 composite successfully attained the HL1 classification under the EN45545–2 regulations. The research outcomes offer an innovative approach to advancing rail transit materials, with significant implications and practical application value.