As a polymer (like a thermoset resin) cures from liquid to solid, the cross-link density increases and this change is accompanied by a significant production of heat and an increase in material stiffness. The ability to predict the value of material stiffness at discrete times during the process of curing would be helpful in process monitoring. This research examines an epoxy-amine system during cure, and makes an in situ characterization using embedded piezoelectric (PZT) chip sensors. A new concept of using ultrasonic-time cure-temperature measurement is proposed for predicting the modulus at any given time during cure and at any given level of curing temperature. The reliable results obtained with this method may enable the quantitative characterization of the properties of the more complex state of cure in the cement-based materials.
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