Investigation on the flame retardancy, thermal and mechanical properties of epoxy resin/cyanate ester composites based on mSiO2@ZrPB and DOPO‐HQ

Abstract

AbstractHerein, we fabricated a hybrid (mSiO2@ZrPB) by modifying mesoporous silica (mSiO2) with zirconium N,N′‐piperazine (bismethylene phosphonate) (ZrPB) via a self‐assembly method, and studied the effects of the combination between mSiO2@ZrPB and 10‐(2,5‐dihydroxyphenyl)‐10H‐9‐oxa‐10‐phospha‐phenantbrene‐10‐oxide (DOPO‐HQ) on the curing behavior, flame retardancy, mechanical/thermal properties of epoxy/cyanate (EPCE) copolymer. The EPCE composite containing 8.0 wt% DOPO‐HQ and 2.0 wt% mSiO2@ZrPB reaches UL‐94V‐0 with the highest limiting oxygen index of 30.5%, and exhibits a reduction of 34.1% on the peak heat release rate and a reduction of 26.8% on the total heat release compared with pure EPCE. The flame‐retardant mechanism is mainly attributed to the catalyzing carbonization effect of both DOPO‐HQ and mSiO2@ZrPB in the condensed phase. Moreover, the EPCE composites have improved thermal resistance (i.e., an increase in glass transition temperature). In addition, the tensile and impact strengths of the composite containing 9.0 wt% DOPO‐HQ and 1.0 wt% mSiO2@ZrPB are respectively increased by 19.1% and 18.9%, with respect to those of pure EPCE. Moreover, the EPCE composites exhibit excellent dielectric properties. Additionally, the curing and thermal‐oxidative degradation behaviors of EPCE and its composites were investigated in more detail. The work provides a new strategy for preparation of EPCE composites with excellent comprehensive properties.