Conclusions on the Process in Isothermal MDR

Some parameters are of considerable interest, regardless of the nature of the rubber and vulcanizing agent, such as the temperature of the dies, the thickness of the sample, and the quality of the contact between the rubber and the dies. They were considered using the data given by calorimetry, using a numerical treatment taking all the facts into account. 

The nature of the vulcanizing agent and of the rubber (i.e., EPDM compounds with peroxide in this instance) is of prime importance to the kinetics of cure the activation energy and the preexponential factor play major roles, and the cure enthalpy is also of some importance in spite of its low value, whereas the order of the overall reaction is 1. Thus, because of the kinetics of cure, the time of cure varies considerably with the temperature, and thus there is a narrow temperature window through which meaningful data can be obtained. The cure enthalpy is rather low and thus does not intervene much in the process. Nevertheless, DSC experiments, which are based on measuring the enthalpy evolved, are also commonly used for determining the kinetics of cure [12]. 

Two parameters that are not often considered in MDR were examined the quality of contact between the rubber and dies, and the thickness of the sample. Both these parameters play a role at the beginning of the course, being responsible for a change in the process of heating and thus the progress in the cure. The times for the values of 5 and even 50% maximum modulus can be strongly affected by these two parameters. 

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