Dynamic mechanical and dielectric characterisation of amylose¯glycerol films

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 alpha -relaxation or glass transition process. This indicated that although glycerol was an effective plasticiser of amylose, amylose¯glycerol mixtures are only partially miscible.