EXPERIMENTAL-STUDY OF VISCOELASTIC AND THERMAL-PROPERTIES OF GLASSES AND POLYMERS NEAR GLASS TRANSITIONS

Viscosity of several inorganic glasses and amorphous polymers have bee n measured under pure shear deformation mode by using a sandwich metho d and utilizing a sensitive optical technique in the temperature range from the room temperature up to the glass transition temperatures. Fr om the temperature dependence of the viscosity, activation energies co ntrolling the viscous deformation were determined. Two different relax ations were superposed in materials containing long molecular chains, while a single relaxation was observed in materials without the chain. The thermal conductivity, thermal diffusivity, and heat capacity of g lasses have been determined simultaneously during an annealing or a st abilization process of glasses below the glass transition by using a h ot-wire method. Three quantities showed relaxations, and the relaxatio n times were about the same for three quantities. The activation energ y for the process was determined from the temperature dependence of th e relaxation time. The relaxation time was around 300 s at the glass t ransition.