Abstract
Curing kinetics of natural rubber/ethylene propylene diene monomer (NR/EPDM) blends at different ratios of 2,2’-dithiobis(benzothiazole) (MBTS) and zinc diethyl dithiocarbamate (ZDEC) were studied. NR/EPDM blends were prepared using curative migration control technique. Kinetics studies employ Deng-Isayev and Kamal-Sorour models and kinetics parameters were evaluated using measured data from Moving Die Rheometer. Rate constant (k) and orders of reaction (n and m) were estimated through multivariable optimization using Matlab and activation energy (E) was determined using Arrhenius relationship. From the results, it is evident that the experimental data were in a good agreement with Kamal-Sorour model. It is also found that autocatalytic mechanism was more controlling than the others as indicated by k2>k1. Results also shows that rate constants were greatly influenced by temperature and the types of accelerator, while orders of reaction were dependent on temperature and independent on the types and amounts of accelerator. Combination of MBTS and ZDEC reduces energy activation of autocatalytic reaction. For desirable rate of curing, its ratio of 1.4 to 0.2 gave the lowest activation energy.
Keywords: kinetics study, vulcanization, NR/EPDM, Deng-Isayev, Kamal-Sorour.
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