Step response analysis in DSC - a fast way to generate heat capacity spectra

A new method of step response analysis in DSC was developed which allows the fast generation of heat capacity spectra. In common temperature modulated calorimetry, like 3 omega -method, AC-calorimetry and temperature modulated differential scanning calorimetry (TMDSC), periodic perturbations are used to get dynamic heat capacity. In contrary, the proposed method uses a single step in program temperature followed by an isothermal segment to obtain the spectrum of heat capacity. To follow system evolution with time or temperature, one can repeat the temperature step, like in StepScan-DSC (TM) (PerkinElmer Instruments), several times also in a non-periodic manner. Measured heat flow rate is evaluated in time domain. With this method, it is possible to cover more than two orders of magnitude in frequency in a single measurement. This allows a dramatic shortening of the measuring time compared to TMDSC. A linearity check and the comparison with TMDSC results are presented. Complete data analysis is performed by a software available for download from our website. (C) 2001 Elsevier Science BN. All rights reserved.