Experimental Study of Viscoelastic and Thermal Properties of Glasses and Polymers near Glass Transitions

Abstract

Viscosity of several inorganic glasses and amorphous polymers have been measured under pure shear deformation mode by using a sandwich method and utilizing a sensitive optical technique in the temperature range from the room temperature up to the glass transition temperatures. Prom the temperature dependence of the viscosity, activation energies controlling the viscous deformation were determined. Two different relaxations 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 glasses have been determined simultaneously during an annealing or a stabilization process of glasses below the glass transition by using a hot-wire method. Three quantities showed relaxations, and the relaxation times were about the same for three quantities. The activation energy for the process was determined from the temperature dependence of the relaxation time. The relaxation time was around 300 s at the glass transition.