Flame retardant epoxy resin toughened and strengthened by a reactive compatibilizer

A flame retardant (FAFD) containing furan groups has been synthesized using furfuryl amine, furaldehyde and 9,10-dihydro-9-oxa −10-phosphaphenanthrene 10-oxide and its use in epoxy (EP) assessed. A reactive compatibilizer (EIA) containing double bonds and EP groups was prepared to modify the interface between FAFD and EP. Incorporation of only 6 wt% FAFD in EP imparts a UL-94 V0 rating and a LOI value of 34.6 vol% for combustion. FAFD exhibits a flame retardant effect in both gaseous and condensed phase. Furthermore, the presence of 1 wt% EIA improves the tensile and impact strength of EP to 77 MPa and 5.7 kJ/m2, respectively. This suggests that the compatibility between EP and FAFD is improved greatly in the presence of EIA without loss of flame retardancy. The EP group of EIA can react with EP resin, and the double bond of EIA can react with a furan nucleus of FAFD via Diels-Alder reactions. Thus, the interfacial adhesion between EP and FAFD is increased leading to increased impact and tensile strength of flame retardant EP. This provides a good method for regulation of the performance of flame retardant EP using a small amount of reactive compatibilizer.