The Glass Transition in Strong and Fragile Glass Forming Liquids

A time domain dielectric spectrometer was developed to measure the dielectric relaxation of materials over more than eleven orders of magnitude of time. This instrument has the ability to measure dielectric polarization from approximately 100 nanoseconds to more than 20,000 seconds, which corresponds to a frequency range of 1.6 megahertz to 8 microhertz. The instrument was used to measure characteristics of the glass transition of two glass forming liquids, glycerin, a strong liquid, and triphenyl phosphite, a fragile liquid. The data were analyzed using a mesoscopic model which describes the dielectric material in terms of dynamically correlated domains. The effect of anneal time on the glass transition was studied, but no dependence of the transition on anneal time was observed.