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Implantable microdielectric sensors are routinely used to monitor the cure of thermosetting polymers. Until recently, the cure monitoring of Reaction Injection Molding (RIM) processes has been difficult due to the short reaction times of RIM materials in relation to the time required to make the dielectric measurements. New high-speed hardware and software (8.3 milliseconds per measurement) has been developed for the dielectric cure monitoring of RIM systems. Dielectric curing data collected with both the existing and new hardware and software are discussed.

A new method and associated equipment has been developed for non-destructively following the progress of the cure of thermoset phenolic molding materials, during a molding operation. It is based on passing an ultrasonic pulse signal through the material as it is curing. The velocity of sound in the material increases monotonically with increases in modulus. Modulus, in turn, increases with increasing degree of cure. Through this method, it is possible to determine when a molded part is sufficiently cured to be removed from the mold. Cure development during compression molding is reported on four phenolic molding compounds, at three different cure temperatures.