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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.

Parts made from phenolic molding materials must be postcured to promote the thorough crosslinking required for end usage at temperatures above about 175°C. Since the time and energy used in postcuring can represent about ten percent of part cost, efficient postcuring offers significant potential savings. Based on a kinetic description of the phenolic crosslinking reaction, we have developed a computer model to predict the development of the glass transition during postcure. This model provides a convenient CAD tool for minimizing postcuring costs.