A Flame-Retardant Epoxy Resin Containing P/N/S With Comparable Transparency and Mechanical Performance

A flame retardant (MBATP) with exceptional performance, incorporating three flame-retardant elements (P/N/S), was synthesized using 2-amino-1,3,4-thiadiazole, 9,10-dihydro-9-oxo-10-phosphophenanthrene-10-oxide, and 4-methylsulphonyl benzaldehyde as raw materials, along with a curing agent to produce flame-retardant epoxy resins (FREPs). The chemical structure of MBATP was confirmed through FT-IR, 1H NMR, and 31P NMR characterization. The study investigated the effects of different contents of MBATP on the curing behavior, flame-retardant effect, thermal stability, combustion characteristics, mechanical properties, and transparency of FREPs. The study revealed that the introduction of MBATP led to a decrease in the maximum decomposition rate while simultaneously facilitating the early decomposition of epoxy resin (EP). The FREP-4 (4 wt% MBATP) attained a V-0 rating through the UL-94 standard, accompanied by an oxygen index of 33.5%. Furthermore, total smoke, the peak heat release rate, and total heat release emission of FREP-4 were diminished by 26.1%, 67.4%, and 25.5%, respectively, compared with EP. Residual carbon and volatile gas emissions tests showed that MBATP effectively contributed to flame retardancy in both the condensed phase and gas phase. The FREPs exhibit a significant degree of transparency, and their mechanical properties have been slightly enhanced. This study has promising applications in advanced optical technologies.