Thermooxidative degradation and its kinetics of natural rubber coagulated by microwave radiation
| Autor: | Yanfang Zhao, Yongping Chen, Jianhe Liao, Lu-Sheng Liao, Yi-Min Li, Can-Zhong He |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | Journal of Polymer Engineering. 32:511-517 |
| ISSN: | 2191-0340 0334-6447 |
| DOI: | 10.1515/polyeng-2012-0118 |
| Popis: | The thermooxidative degradation of natural rubber (NR) coagulated by microwave radiation (NR-m) was investigated by thermogravimetry (TG) analysis, and compared with NR coagulated by acid (NR-a). It was found that the degradation process is not a one-step reaction, the main degradation process occurs at 300–400ºC, and the equilibrium degradation temperatures of NR-m are higher than those of NR-a. Different methods were used to find the most probable kinetic model and the Arrhenius parameters (activation energy E and preexponential factor A) for the main stage of thermooxidative degradation of NR-m. The results show that the values of E and A, obtained from the Coats-Redfern method, are highly variable with the kinetic model chosen and the heating rate (β), and the apparent activation energy (E0) when β approaches zero for the Dn type kinetic model is in the range of 96.7–106.4 kJ ∙ mol-1. The mean values of E, calculated by the Friedman and Flynn-Wall-Ozawa (FWO) methods, are 113.8 and 83.3 kJ ∙ mol-1, respectively, suggesting E in the range of 83.3–113.8 kJ ∙ mol-1. Comparison of these two ranges indicates the most probable kinetic model to be Dn type kinetic models, corresponding to a diffusion-controlled mechanism. |
| Databáze: | OpenAIRE |
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