Reduced Time Approach to Curing Kinetics, Part II: Master Curve from Nonisothermal Data

Nonisothermal curing kinetic data obtained from differential scanning calorimetry (DSC) for a rubber compound are corrected for the effects of temperature lag between the DSC sample and furnace. The method of Eder and Janeschitz-Kriegl, which is based on experimental data alone without reference to any kinetic model, is used for these corrections. A method is presented for shifting the corrected nonisothermal curing kinetic data with respect to an arbitrarily chosen reference temperature to obtain a master curve. The method is based on experimental data alone without assuming any specific form of kinetic model. When the isothermal curing kinetic data for the same material are shifted with respect to the same reference temperature, a master curve is also obtained which basically overlaps the corresponding master curve from nonisothermal data. It follows that nonisothermal DSC measurements provide the same curing kinetic information as isothermal ones, only over a wider range of temperatures. The shift factors obtained from experimental data alone are compared with the corresponding values calculated from a kinetic model with an Arrhenius type of temperature dependence. This serves as a means of model evaluation. It is concluded that the kinetic model is good at describing isothermal curing kinetic data. But it yields reliable curing kinetic information over a narrower range of temperatures than nonisothermal data alone without resort to any model. The Arrhenius extrapolation of the limited isothermal data to a wide range of temperatures is quite good.