Thermal degradation of polystyrene

Living polystyrene samples, both solid and in dilute toluene solution, were thermal degraded under extremely clean conditions in a range of temperatures from 200 to 325°C. The degradation was found to be a first‐order reaction. Pyrolyzed samples were analyzed with regard to the change in molecular weight as well as in molecular weight distribution. For the latter, an extraction method is described, which permits, in addition, the activation energy of thermal degradation (48 kcal/mole for the overall reaction) to be obtained. The results are discussed with a view to earlier outlined degradation theories. The presence of weak links in polystyrene as well as the propagation of degradation by reverse polymerization could be excluded. A radical chain reaction is assumed to be the mechanism of degradation.