PHENOMENOLOGICAL DESCRIPTION OF THE INTERNAL FRICTION SPECTRA IN GLASS-FORMING AND GLASSY SYSTEMS

摘要

The internal-friction spectra of glass-forming systems different in chemical nature contain loss peaks in the regions of both viscoelastic and elastic solid states of the system. The loss peaks observed in glassy systems at temperatures TTg cannot be described using the viscosity of the glass-forming system since this parameter cannot be measured at these low temperatures. It is suggested that low-temperature losses are associated with a set of structural subsystems, each characterized by particular local dissipation parameters and elastic constants. The relaxation time of any dissipative process can be expressed as the ratio of a local dissipation parameter to a local elastic parameter. For the α -relaxation(T>Tg),the local dissipation parameter coincides with viscosity. The number of loss peaks in the internal-friction spectrum is related to the number of quasi-independent structural subsystems constituting a particular glass-forming system.The responses of the structural subsystems to external influences are shown to be quasi-independent.