Dynamic mechanical and dielectric characterisation of amylose–glycerol films

Abstract

The dynamic mechanical, dielectric and calorimetric behaviour of amylose films, plasticised with glycerol, was examined as a function of temperature and glycerol content. Two separate relaxation processes were observed. Whereas the temperature of the lower temperature transition, in the vicinity of −50°C, showed a weak dependence on composition, the temperature of the upper transition, in the range 150–50°C, decreased with increasing glycerol content. The activation energy of the lower temperature transition, obtained from the dependence of the frequency of the relaxation peak upon temperature, was typical of a primary α-relaxation or glass transition process. This indicated that although glycerol was an effective plasticiser of amylose, amylose–glycerol mixtures are only partially miscible.