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E. Rudnik, Z. Dobkowski, P.Myśliński


Measurements of the thermal properties of polymers. Part I. The derivalographic method used

in the investigations on the decomposition process in polymers


Polimery 1992, No 5, 212


DOI: dx.doi.org/10.14314/polimery.1992.212

Summary

On an example of non-stabilized bisphenol-A polycarbonate (PC-A) the derivatographic method used for studying polymer decomposition processes was presented. In this method, the characteristic decomposition temperatur es (namely the initial temperature of rapid decomposition, Tpr, the temperature of maximum decomposition rate, Tmn; the temperature of the maximum oxidation rate, Tmw) and the temperature of the termination of the decomposition process, Тkr) as well as the apparent activation energies, E, can be determined. The following methods of the calculation of E values were described: the Ozawa method of isoconversional curves in the whole range of conversion a of the decomposition process and the Kissinger method using the particular points of the decomposition process, i.e. that of the initial decomposition where a = 0 and that of the maximum rate of ecomposition. The procedure for determining the timetemperature characteristics of a polymer material from Epr at a = 0 and for predicting its long-term performance in air was proposed. In the case of PC-А, it was found that Epr = 88.9 kJ/mole and time of performance under processing conditions at 280-300°C is 30-60 minutes.


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