MODELING OF THE EXPERIMENTAL PHENOMENA OCCURRING DURING SIMULTANEOUS TG-DSC MEASUREMENTS OF WATER DESORPTION

For the determination of the heat of a given process with a differenti al scanning calorimeter, it is not only necessary to measure the DSC c urve, but also to construct the baseline. If the differential scanning calorimeter is coupled with a balance, the gravimetric measuring valu es can be used for the construction of the baseline. In this paper, th e model of an input function was calculated from a model equation of t he baseline and the gravimetric signal. The corresponding output funct ion results from this together with a model apparatus function by calc ulation of the convolution integral. Using the regression analysis, th e required model coefficients were obtained from the experimental DSC values. To prove the given model, it was applied to investigations of the desorption process of adsorbed water on zeolites by simultaneous T G-DSC measurements. It was found that with the help of this model, by integration of the corresponding DSC curves, suitable enthalpy values could be obtained even for unfavourable shapes of the baseline.