Numerical modeling and analysis of temperature modulated differential scanning calorimetry: On the separability of reversing heat flow from non-reversing heat flow

Temperature modulated differential scanning calorimetry (TMDSC) is a recent ly developed method used to analyze thermal properties of materials such as heat capacity C-p and heat flow under isothermal or continuous heating con ditions. However the method of measuring C-p in TMDSC and the separation of reversing heating flow (RHF) from non-reversing heat flow (NHF) depends on the precondition that the system is linear and the effect of non-reversing heat flow is also linear or very close to being so. In this paper, a numer ical simulation method is used to study heat capacity C-p, NHF and RHF in v arious situations. It is found that using Fourier Transform to calculate C- p is applicable under steady state condition where there is no NHF. In the NHF releasing temperature range, the measured C-p value varies with differe nt NHF patterns and modulation conditions even if C-p stays constant over t he whole temperature range concerned. It appears that this method should be used with discretion in terms of the explanation of experimental results. Quantitative separation of RHF from NHF still remains a challenge if the me chanism of NHF and its effect on the system is not clear. (C) 2000 Elsevier Science B.V. All rights reserved.