UNIVERSITY OF TORONTO

Canada

Keywords: Free Volume Fraction, PVT, Viscosity

This research investigated the relationships of the pressure-volume-temperature (PVT) and the zero-shear viscosity data of polymer melts through their correlations with the free volume. Polystyrene (PS) and polybutylene succinate (PBS) were used as case examples in this study. First, the fractional free volume was determined based on the PVT data of pure polymer using the Simha-Somcynsky equation-of-state (SS EOS) or Sanchez-Lacombe (SL) EOS. Then the fractional free volume was also determined based on the zero-shear viscosity using the Doolittle equation. These two data were observed to be almost the same. This implies that the both SS EOS and SL EOS describe the PVT behaviors of a pure melt reasoably well and the Doolittle equation describes the zero-shear viscosity well as a function of the fractional free volume. Efforts are also made to extend this concept of correlating the PVT data to the zero-shear and high-shear viscosities of a polymer/gas mixture by using Doolittle equation, Cross-Carreau model, and two EOS.