Kinetic analysis of pyrolysis of cross-linked polymers

Decomposition of crossed-linked polymers in an inert atmosphere occurs in such a way that they tend to conserve the structure of their matrix. Bond breaking inside the polymer matrix requires a large amount of energy. That is why decomposition of crossed-linked polymers preferentially takes place via a chemical conversion of side chains. Probably, to a first approximation, the side chains can be considered as being almost independent during the decomposition. In other words, the overall decomposition can be described as a set of parallel processes. In such a case, the final residue of the polymer after decomposition can be described as a substance with certain properties independent of the way of obtaining this residue. The accuracy of approximation of kinetic information by using such assumptions is exemplified in four-stage decomposition of cross-linked (rigid) polyurethane in nitrogen. As shown, the set of four activation energies, obtained as a result of the approximation, can be used for sufficiently accurate prediction of the decomposition under arbitrary thermal conditions. (c) 2004 Elsevier Ltd. All rights reserved.