CURE KINETICS OF BUTYL RUBBER CURED BY PHENOL FORMALDEHYDE RESIN

Abstract

The characterization of rubber compounds is a necessary step for simulating rubber products manufacturing processes. We study experimentally and model computationally compounds of Butyl rubber cured by Phenol Formaldehyde Resin, a rubber used for making curing bladders, a key component in the tire industry. Several compounds, differing in the proportions of resin, Zinc Oxide, Polychloroprene (CR) and Stearic Acid, are experimentally tested during the curing process using a moving die rheometer. The experimental results are used to find the parameters of two well established kinetic models, namely the Nth order and the Kamal-Sourour models. Both models include an ordinary differential equation for the degree of cure and an algebraic relation between torque and temperature. The fitting of the model parameters is rearranged as an optimization problem, and solved using the Levenberg-Marquadt algorithm. The results show that both models are able to represent the behavior of these compounds, although the more involved Kamal-Sourour model performs better for early times, as expected. The parameter values found are useful for numerical simulations of curing bladder manufacturing processes, and as a reference for further studies of similar compounds.