Superheating effects during the melting of crystallites of syndiotactic polypropylene analysed by temperature-modulated differential scanning calorimetry

Temperature modulated differential scanning calorimetry (TMd.s.c.) was applied in a study of syndiotactic polypropylene. The crystallites melt from their lateral surfaces only and the kinetics shows up in the imaginary part c " of the complex specific heat. Theoretical analysis predicts and experiments confirm that c " increases linearly with the underlying mean heating rate and the modulation period. Furthermore, it can be shown that c " is inversely related to the superheating effective during melting. Use of the relation yields for syndiotactic polypropylene values in agreement with direct measurements employing conventional d.s.c. (C) 1998 Elsevier Science Ltd. All rights reserved.