Simultaneous dielectric and dynamic mechanical analysis of thermosetting polymers

This work presents a new method to measure simultaneously the dielectric loss factor and viscosity of thermosetting polymers during various cure cycles. A microdielectric sensor was mounted in the bottom plate of a parallel plate rheometer. Three types of high performance laminating resins were investigated. During non‐isothermal curing, dipole peaks were found to correspond to softening/devitrification, the maximum in the loss factor followed the same heating rate dependence as the minimum in the viscosity, and dipole peaks were observed to correlate with vitrification when the cure temperature was below the ultimate glass transition temperature of the resin.