Temperature-modulated calorimetry of the crystallization of polymers analyzed by measurements and model calculations

The response of temperature-modulated differential scanning calorimetry (TM DSC) to irreversible crystallization of linear polymers was investigated by model calculations and compared to a number of measurements. Four differen t exotherms were added to a typical modulated, reversible heat-flow rate in order to simulate irreversible crystallization. It was found that the reve rsing heat-flow rate of the TMDSC in response to such irreversible crystall ization exotherms is strongly affected by tbe shape of the transition and t he phase-angle where the exotherm occurs. A comparison with the experimenta l data gave valuable insight into the transitions, as well as the nature of the TMDSC response which is usually limited to an analysis of the first ha rmonic term of the Fourier series that describes the heat-flow rate.