Structural relaxation of polyvinyl acetate (PVAc)

Structural relaxation of polyvinyl acetate (PVAc) was studied by mercury dilatometry and differential scanning calorimetry. Tool-Narayanaswamy-Moynihan (TNM) and Adam-Gibbs-Scherer (AGS) models were used to fit numerous experimental data. Single set of volume and enthalpy relaxation parameters describing all performed experiments was found for each model. Comparison of volume and enthalpy relaxation was made on the basis of TNM parameter values. The famous volume relaxation measurements made by Kovacs [Fortschr Hochpolym Forsch 1963;3:394-507] were successfully fitted using the same set of parameters. Furthermore, several non-fitting methods of TNM parameters' estimation (including, e.g., peak-shift method or inflectional analysis) were applied to our data and their critical comparison is outlined. For most methods a good agreement with curve-fitting results was achieved.