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 th e fast generation of heat capacity spectra. In common temperature modulated calorimetry, like 3 omega -method, AC-calorimetry and temperature modulate d differential scanning calorimetry (TMDSC), periodic perturbations are use d to get dynamic heat capacity. In contrary, the proposed method uses a sin gle step in program temperature followed by an isothermal segment to obtain the spectrum of heat capacity. To follow system evolution with time or tem perature, one can repeat the temperature step, like in StepScan-DSC (TM) (P erkinElmer Instruments), several times also in a non-periodic manner. Measu red heat flow rate is evaluated in time domain. With this method, it is pos sible to cover more than two orders of magnitude in frequency in a single m easurement. This allows a dramatic shortening of the measuring time compare d to TMDSC. A linearity check and the comparison with TMDSC results are pre sented. Complete data analysis is performed by a software available for dow nload from our website. (C) 2001 Elsevier Science BN. All rights reserved.