Nonsteady thermal decomposition of plastics

Abstract

We are interested in the problem of nonsteady thermal decomposition of plastics subjected to very large heat flows from the theoretical standpoint. First, the fundamental equations governing both char layers and pyrolysis zones are introduced on the basis of a new model for pyrolysis zones. Second, these equations are solved for the case where a large quantity of heat is introduced to the char surface and the recession velocities of the char surface and the pyrolysis front are obtained. Finally, these results are compared with the existing experimental data. We come to the following conclusions: (1) the temperature of the pyrolysis front reaches an almost constant value (1200°R) in a short time, (2) the width of the high-temperature zone is very small, (3) the penetration velocity of the pyrolysis fron shows a sufficient agreement with the experimental data, and (4) the recession velocity of the char surface coincides with the experimental data when surface temperature is not too high.