Thermal degradation of poly (ε-caprolactone)

The thermal degradation kinetics of poly (epsilon-caprolactone) (PCL) in solution was investigated at various temperatures (170-245 degreesC). The degradation was also investigated by pyrolysis at various temperatures (280-330 degreesC). The time evolution of molecular weight distribution (MWD) was obtained using gel permeation chromatography. It was observed that in pyrolysis, PCL degrades by specific chain end scission by unzipping of monomers from the hydroxyl end of the polymer chains. In contrast, the degradation of PCL in solution is by random chain scission. A continuous distribution kinetics model is proposed to explain the observed behaviour under both conditions. The activation energy, determined from the temperature dependence of rate coefficients, was 61 kJ/mol and 201 kJ/mol for the degradation in solution and by pyrolysis, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.