Real-time Monitoring the Vulcanization of EPDM Rubber with Ultrasound: A Study on the Reaction Kinetics

In an attempt to study the reaction kinetics of ethylene–propylene–diene (EPDM) rubber, using a noninvasive and nondestructive ultrasonic technique, several compounds varying with amounts of sulfur and accelerator were prepared. A relationship between the calibrated ultrasonic velocity and the change of molecular structure during vulcanization was investigated and described by an exponential equation. The resulting characteristic parameters, related to the cure degree and rate, were obtained through the data fitting. The experimental results showed that with the increase of content of sulfur and accelerator, the cure degree increased, but the reaction rate constant decreased.