Process of Cure in Isothermal MDR

The process of cure taking place in the rubber sample in the isothermal MDR has been deeply studied in a previous paper [18], and some results obtained are reported. 

FIGURE 3.11 Torque-time curves obtained with the oscillating disc rheometer (ODR) and with the moving die rheometer (MDR) with the same rubber compound. 

The first objective was an in-depth study of the process of cure in the sample between the MDR dies, by considering not only heat transfer through the sample but also the heat generated by the overall cure reaction. Three various EPDM samples were selected with different percentages of peroxide ranging from 2 to 19%, associated with a cure enthalpy between 14 and 51 J/g. Another purpose was to evaluate the state of cure in the sample at various times, and thus profiles of temperature and of state of cure developed through the thickness of the rubber can be obtained at various times, especially associated with typical values of the torque (5, 50 and 95% of maximum torque). Comparison could be made between the values of the state of cure and the value of the torque. 

The materials used for curing (Hutchinson) are described in Table 3.2 

The peroxide used was ti(ter-butyl-peroxy-isopropyl) benzene Perkadox 14-40. For these samples, the density is 1.18 g/cm the heat capacity is 2 J/g.deg and the heat conductivity is 0.25 W/m.deg. 

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