Pyrolysis of poly-α-acetoxystyrene, a polymer derived from polystyrene and poly(vinyl acetate)

Abstract

The pyrolysis of poly-α-acetoxystyrene was investigated by using two methods thermogravimetry, and a reactor working under dynamic conditions coupled with a chromatograph. Thermogravimetry was used firstly with a constant heating rate and secondly under isothermal conditions. Two different degradation steps for the polymer were found, the first between 140 and 200°C and the second above 220°C. The kinetics of the overall pyrolysis were studied for the first thermal degradation step. The degradation order is zero when the weight loss is less than 10%, and unity when the weight loss is between 10 and 32%. The activation energy is about 40 kcal/mole for either order. The results obtained by using dynamic and isothermal thermogravimetry are in good agreement. Volatile products were identified and analysed by using a reactor working under dynamic conditions coupled with a chromatograph. The decomposition is similar to that of poly(vinyl acetate) and different to that of known substituted polystyrenes. Acetic acid was the main component of the volatile products (90–95%), the others being the monomer and acetophenone.