Curing Behavior Of A Phenol-terminated Hyperbranched Curing Agent With Epoxy

The curing behavior of diglycidyl ether of bisphenol A （DGEBA） and ahyperbranched curing agent in stoichiometric ratio was studiedcomprehensively. The novel hyperbranched polymer is based onpoly（phenylene oxide）s （HPPO） with phenolic terminal groups. Theisothermal and dynamic curing behaviors of the mixture of HPPO andDGEBA were studied using differential scanning calorimetry （DSC）, and thegelation point were obtained by thermal mechanical analysis （TMA）. Theisothermal cure kinetics, including the effects of diffusion, were analyzed bythe modified Kamal model, Avrami model, and time-temperaturesuperposition （TTS） kinetics. The dynamic cure data were analyzed usingVyazovkin’s model-free kinetics method, which is consistent with theisothermal cure data when diffusion control is absent. The degree ofconversion at the gel point,α_gel, is constant and much smaller than thetheoretical value. The gelation is accelerated. Diffusion control in this curing system is strong and becomes dominant before vitrification. The ultimateconversion is not affected by this effect. In addition, evolution of T_g as afunction conversion and the isothermal time–temperature–transformation（TTT） diagram were also obtained for this hyperbranched curing system.