Energetics and chemical kinetics of polystyrene surface degradation in inert and chemically reactive environments.

Polystyrene (PS) degradation-vaporization produced by intense surface heating has been studied experimentally. Specimens were immersed in the exhaust jet of a small laboratory rocket motor, and the linear regression rate was measured as a function of surface heating rate; corresponding surface temperature levels were obtained by monitoring the thermal radiation emitted from the heated surface. Porous specimens, through which a series of test gases were passed to emerge at the heated surface, permitted these data to be gathered in chemically reactive environments. Correlation of all these data, in both inert and chemically reactive environments, was possible both on the basis of an energy balance struck at the regressing surface and an Arrhenius type of chemical kinetic description of the surface degradation process. Although expected, this represents the first demonstration that both relations are satisfied simultaneously - a result of great importance to the formulation of combustion theories of, e.g., hybrid rocket motors, solid propellant ignition, flame spreading, and deflagration. (Author)