Synthesis of a novel, multifunctional inorganic curing agent and its effect on the flame-retardant and mechanical properties of intrinsically flame retardant epoxy resin

Traditional curing agents have only a single property, while traditional synthetic organic flame-retardant hardeners often show poor tolerance to oxidants, strongly acidic or alkaline reagents, and organic solvents and have toxicity problems. Here, a novel and multifunctional flame-retardant curing agent of the inorganic substrate multifunctional curing agent of the inorganic substrate (FCIN) was proposed first and successfully prepared, and then an intrinsically flame-retardant epoxy resin (EP) was prepared by covalently incorporating FCIN nanoparticles (FCINs) into the EP. The curing behavior of the FCINs was investigated, showing that FCIN/EP expresses a higher global activation energy than tetraethylenepentamine (TEPA)/EP and that the FCINs had strong interfacial adhesion to the EP matrix. Additionally, the FCINs were well dispersed and provided a remarkable improvement in mechanical and flame-retardant properties of the intrinsically flame-retardant EP. With the incorporation of 9 wt % FCINs into the EP, dramatic enhancements in the strength, modulus under bending, and toughness (approximate to 36%, approximate to 109%, and approximate to 586%, respectively) were observed, along with 85.2%, 46.4%, 98.3%, and 77.26% decreases in the peak heat release rate, total heat release, smoke production rate peak, and total smoke production, respectively, with respect to that of TEPA/EP. The mechanisms of its flame-retardant, smoke-suppression, and failure behaviors were investigated. The development of this unconventional, multifunctional flame-retardant curing agent based on an inorganic substrate showed promise for enabling the preparation of a variety of new high-performance materials (such as intrinsically flame-retardant EP and functional modified polyesters). (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46410.