Comparison of Expressions for Cooperative Properties in Glass-Forming Liquids

The results of the Adam and Gibbs statistical-mechanical model for relaxation in glass-forming systems are compared with the Williams, Landel, and Ferry empirical correlations. The emphasis is on determining quantitative expressions for the differences in the relationships for comparison with the available experimental data. It is found that the qualitative differences cannot quantitatively be distinguished from the bulk of the existing data but that the differences become magnified for systems with low glass-transition temperatures.