A kinetic modeling study of the thermal degradation of halogenated polymers

• Published in: Journal of analytical and applied pyrolysis Vol. 72; no. 2; pp. 253 - 272
• Main Authors: Mehl, M., Marongiu, A., Faravelli, T., Bozzano, G., Dente, M., Ranzi, E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2004
• Subjects: Detailed modeling; Polychloroprene; Polyvinylbromide; Pyrolysis; Thermal degradation; Polychloroprene; Pyrolysis; Detailed modeling; Polyvinylbromide; Thermal degradation
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2004.07.007

This paper presents a semi-detailed and lumped kinetic model of poly(chloroprene) thermal degradation. This is the extension of a previous paper in which a polyvinylchloride (PVC) pyrolysis mechanism was presented. The mechanism of 38 species and pseudo-components (molecules and radicals) involved in about 190 reactions reproduces the main characteristics of poly(chloroprene) degradation and volatilization quite well. The presence of the two-step mechanism – the first step of which corresponds to dehydrochlorination/condensation and the second to TAR release and residue CHAR formation – are correctly predicted both in quantitative terms and in the temperature ranges. The model was validated by comparison with some thermogravimetric analyses. Similarities and differences with PVC are discussed both in terms of degradation behavior and chemical mechanisms. A further extension of the proposed approach refers to a brominated plastic (polyvinylbromide). In fact, a few modifications to the rate constants of the kinetic model also predict the pyrolysis of this plastic quite well. When compared with the typical one-step global apparent degradation models, the approach proposed here is much more flexible: in fact it spans quite large operating ranges, especially when it comes to predicting product distributions. The initial results of these product predictions, even though still limited, are encouraging and confirm the validity of the proposed model.