Synthesis of hexa (imidazolyl) cyclotriphosphazene and its performance as curing catalyst of epoxy resin

Abstract

Hexa (imidazolyl) cyclotriphosphazene (HImCP) was synthesized by nucleophilic substitution reaction of hexachlorocyclotriphosphazene with imidazole. The chemical structure was characterized by FT-IR,1H-NMR, and 31P-NMR. Then the as-prepared HImCP was utilized as curing catalyst for curing of diglycidylether of bisphenol A(E51)with methylhexahydrophthalic anhydride(MHHPA). Its influence on the storage stability at room temperature and curing activity at high temperature of E51/MHHPA system was studied by gelatum time and non-isothermal DSC analysis. The mechanical performance,glass-transition temperature(Tg),and thermostability of the obtained epoxy thermosets were also investigated. The results show that HImCP is a good latent curing catalyst contrast with unmodified imidazole. When the epoxy resin curing system contains 1% (mass fraction) of HImCP,it exhibits improved storage stability at room temperature as compared to that containing imidazole,as well as satisfied curing activity at high temperature. In addition,the obtained thermoset has higher tensile strength,Tg and thermostability than that resulted from imidazole.

Keywords

• epoxy resin
• imidazole
• hexachlorocyclotriphosphazene
• latent curing catalyst