Effect of Excessive Iodonium Salts on the Properties of Radical-Induced Cationic Frontal Polymerization (RICFP) of Epoxy Resin

Radical-induced cationic frontal polymerization (RICFP) can considerably improve the curing efficiency of epoxy resins. However, conditions, such as excessive initiators, cause violent reactions of frontal polymerization, adversely affecting the mechanical performance of the product. Herein, the effect of reaction rate on the tensile strength of RICFP-cured bisphenol A diglycidyl ether was studied, and the optimum ratio was measured using the response surface methodology. Components and molecular structures of the products were analyzed using gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The principle that explosive polymerization affects the tensile strength of products was further explained. Additionally, it was found that the epoxy value of resin may determine whether RICFP could be achieved, which could be remedied by adding ethylene glycol diglycidyl ether, considerably promoting the reactivity of the system.