Modelling pyrolysis of char forming polymers

摘要

A mathematical description of the pyrolysis of char-forming polymers is presented which uses a simple competitive reaction scheme for the decomposition of the polymer. The model fully accounts for change of volume in the solid during pyrolysis (a feature neglected by most models to date) and includes different thermal properties for the char and the polymer. Thus a preliminary analysis of the low density intumescent char forming case is possible. In its simplest form, the model consists of a coupled set of non-linear integropartial differential equations for the temperature, polymer mass fraction and change of volume. The equations are solved using spatially and temporally adaptive finite-difference methods, where the node density at any point in the grid is proportional to the solution gradient. An approximate solution method, which reduces the model equations to a simple pair of ordinary differential equations, is discussed as well as a simple method of characterising TG data.