Modulated differential scanning calorimetry: 14. Effect of molecular interactions on glass transition behaviour and increment of heat capacity in miscible polymer blends

Molecular interactions in miscible polymer blends influence glass transitio n (T-g) behaviour and the increment of heat capacity at T-g. Whether the gl ass transition temperature and the increment of heat capacity versus compos ition show positive or negative deviations from linearity for blend systems depends on specific molecular interactions. In the non-interacting system, poly(vinyl acetate)/poly(methyl acrylate), the glass transition temperatur e and the increment of heat capacity show a linear behaviour with compositi on. Thermodynamic theoretical considerations concerning the non-linear beha viour of the glass transition temperature and the increment of heat capacit y with composition in miscible polymer blends are developed in this paper. (C) 1999 Elsevier Science Ltd. All rights reserved.