An on-line data acquisition system for thermogravimetry using the IBM S/7 computer followed by data reduction on a 360/195 is described by means of flow charts. The system is designed so that no knowledge of programming is required to acquire, display and manipulate data on an interactive graphics terminal. The program not only extracts weight loss data, but also computes the energies of activation, E, for any selected weight loss interval by two methods, i.e., tabular integral and derivative. The system is demonstrated by a study of the activation energies for loss of water, loss of carbon monoxide, and loss of carbon dioxide during the thermal decomposition of calcium oxalate monohydrate. The results are in good agreement with the best literature values. The derivative method was found to give more consistent results than the tabular integral approach because of problems encountered in the precise measurement of temperature in the thermobalance.
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