Investigation of thermal degradation of poly-(4n-alkylstyrene) with long alkyl chain (C6-C10) by pyrolysis-gas chromatography/mass spectrometry

The thermal degradation of a series of poly(4-n-alkylstyrenes), from hexyl to decyl, has been studied in isothermal conditions at 600°C using pyrolysis-gas chromatography/mass spectrometry. The type and composition of the pyrolysis products gave useful indications about the mechanism of thermal degradation. It was shown that the main thermal degradation process is depolymerization, like polystyrene. Other thermal reactions involve fragmentation of alkyl side chains. In particular, a new initiation process for depolymerization of polystyrene based polymers was found: a thermal electrocyclic reaction with the formation of divinylbenzene and alkane, and main chain scission with formation of two macroradicals. The formation of cyclic or polyaromatic structures does not take place.