A fire-safe, single-component epoxy resin based on a phosphorus/imidazole-containing latent curing agent and diphenylphosphine

This work reported a flame-retardant, single-component epoxy resin (EP) via introducing diphenylphosphine (DPP) and benzimidazolyl-substituted cyclotriphosphazene (BICP) into EP. The differential scanning calorimetry (DSC) test showed that the onset curing temperature of DPP/BICP-15/10 was 50°C lower than that of BICP-12 due to the catalytic decomposition effect of DPP toward BICP under heating. Besides, the shelf life of DPP/BICP-15/10 at room temperature reached ~14 days, demonstrating good storage stability. EP/DPP/BICP maintained satisfactory thermal properties and showed excellent flame retardancy with a UL-94V-0 classification. Compared with the unmodified EP sample, the peak heat release rate (PHRR) and total heat release (THR) of DPP/BICP-15/13 were decreased by ~68.1% and ~55.1%, respectively. Hence, this flame-retardant, single-component epoxy resin with satisfactory comprehensive properties exhibited great potential for versatile industrial applications.