Flame-retardant single-component epoxy resin cured by benzimidazolyl-substituted cyclotriphosphazene: Storage stability, curing behaviors and flame retardancy

This work reported a flame-retardant single-component epoxy resin via the integration of two bisphenol-A-type epoxy resins (E20 and E53) and benzimidazolyl-substituted cyclotriphosphazene (BICP). The differential scanning calorimetry (DSC) tests showed that the onset curing temperature of E53/E20/BICP was 30°C lower than that of E53/BICP due to the catalytic decomposition effect of E20 towards BICP under heating. Besides, the shelf life of E53/E20/BICP at room temperature reached ∼40 days, demonstrating good storage stability. E53/E20/BICP maintained satisfactory thermal properties and showed outstanding flame retardancy with a UL-94 V-0 classification. Compared with the unmodified EP sample, the peak heat release rate (PHRR) and total heat release (THR) of E53/E20/BICP were decreased by ∼64.1% and ∼39.0%, respectively. Hence, this flame-retardant single-component EP with satisfactory comprehensive properties exhibited great potential for versatile industrial applications.