T. S. Radhakrishnan, M. Rao
Jul 1, 1986
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Influential Citations
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Journal
Journal of Analytical and Applied Pyrolysis
Abstract
Abstract The kinetics and mechanism of the thermal degradation of thiol-terminated liquid polysulphide polymer cured with ammonium dichromate was studied by pyrolysis-gas chromatography and isothermal and dynamic thermogravimetry. Pyrolysis-gas chromatography showed that the nature and composition of the pyrolysates for the liquid and the cured elastomers were essentially the same. Isothermal measurements were made at 268, 280, 290 and 299°C and maxima in the rates of degradation occurred at 28% conversion (α). Isothermal rates calculated from a kinetic model based on random initiation followed by rapid termination by disproportionation were in good agreement with the experimental values. The dynamic experiments were run at several heating rates from 2 to 100°C/min. Analysis of the data based on the random initiation model gave kinetic parameters that agreed well with the isothermal values and with the values obtained by Ozawa's method, confirming the proposed kinetic model for the degradation. The overall activation energy for the degradation ( E d ) was found to be 146.4, 144.1±7.6 and 145.6±7.6 kJ mole −1 by isothermal, dynamic and Ozawa's methods, respectively. The Coats-Redfern method of analysis gave increasing values of E d with increasing heating rates and showed a kinetic compensation effect.