Phenomenological Analysis of the Cured Kinetics in the Order n of the Reaction as a Function of the Temperature of an EPDM Polymer

Abstract

The fabrication of rubber products involves a complex chemical process, which is invariably assisted by temperature and pressure. Obviously, the curing process specifications have a strong impact on the quality and mechanical properties of the final product. Mechanistic kinetic models and phenomenological or empirical models have been used to describe the cure behavior of rubber. The empirical models ignore the chemical details and fit the data to a mathematic functional form where the constants of the model are determined based on experimental procedures such as rheometry. In this paper, we present the phenomenological characterization of the ethylene propylene diene monomer (EPDM) synthetic elastomer by mobile die rheometer (MDR). The kinetic parameters were calculated from Kamal-Ryan, Sestak-Berggren, and the Isayev-Deng methods at different temperatures. An Arrhenius-type function for the order of reaction n is introduced to improve the fit. Finally, Sesták–Berggren and Isayev-Denǵs empirical models were compared in order to determine which best describes the behavior including the proposed expression. The graphical and analytical description of the cure kinetics for the EPDM rubber was obtained consistently. The expression proposed to describe the order of the reaction is predicted to give a better establishment of processing time. It was noted that for EPDM at higher temperatures, the increase of the rate of reaction occurs in short period of time, which could cause premature curing if the supply system is inadequate.