Properties of IPNs of epoxy resin/bismaleimide–allylester copolymer (abstract)

Abstract

Interpenetrating polymer networks (IPNs) were prepared from anhydride‐cured epoxy resin and bismaleimide (BMI) coreacted with triallyltrimellitate (TAT), triallylisocyanurate (TAIC), and diallylisophthalate (DAP), under the same gelling conditions for both the epoxide resin and BMI–allylester comonomer. Dynamic mechanical properties of the IPNs were measured over the temperature range from room temperature to 400 °C. In addition, tensile and thermal degradation properties were measured for these IPNs. The rubbery modulus and primary dispersion temperature (Tα) due to the cured epoxy resin considerably increased with loading of BMI–allylester component. The value of Tα exhibited an asymptotic behavior at high loading, the value increasing in the order of BMI–TAT, –TAIC, and –DAP. The modulus behavior in the rubber state followed approximately the Budiansky’s equation and suggested the formation of IPN. The difference among the asymptotic values of Tα for each series can be explained in terms of polar‐nonpolar solubilities of the components. The most efficient and major increase in Tα which occurred at about 50 wt. % of BMI–allylester component, is based upon an enhanced miscibility between both components as a result of interpenetration. The effects of interpenetration brought about maxima in tensile strength significantly higher than the tensile strength of the component networks and some improvement in thermal resistance at about 50 wt. % of BMI–allylester component.