PRINCIPLES FOR THE INTERPRETATION OF TEMPERATURE-MODULATED DSC MEASUREMENTS - PART 2 - A THERMODYNAMIC APPROACH

摘要

At evaluation of TM-DSC (temperature-modulated differential scanning calorimetry) curves using linear response theory we obtain a complex heat capacity, which consists of a real and an imaginary part. It can be shown that C '' is connected to the time-dependent processes. It includes information about the internal entropy change. In the case of phase transitions and chemical reactions, this internal entropy change is related to the change in structure. For a description of time-dependent processes, a new internal parameter zeta (order parameter) is necessary. zeta is a function of time and describes the kinetics of the system. If the thermodynamic behaviour is known, zeta(t) can be determined. Phenomenological or molecular models for the order parameter zeta(t) can be used for a description of measured TM-DSC curves. (C) 1997 Elsevier Science B.V. [References: 25]