Kinetics of combustion and pyrolysis of polysiloxanes

The mass changes of three types of cured polysiloxane resins (differing in phenyls and methyls) were studied by means of thermogravimetry during heating is air or nitrogen. It was found that the behavior of polysiloxanes depends on the type and content of organic groups. Polymethylphenylsiloxanes with a high part of phenyls showed higher mass decays compared to polymethylsiloxanes, regardless of the surrounding atmosphere. It was possible to estimate the mass losses after combustion or pyrolysis from the known composition of polysiloxanes. The mechanisms of combustion or pyrolysis are very complex processes, but from a formal point of view a system of two first-order equations was sufficient to describe the kinetics. Optimization of the kinetic parameters was performed via a simplex method during simultaneous integration of the kinetic equations.