Pure Polymer PVT Behavior

If one wishes to estimate a specific volume of a polymer in a solution below Tg or Tm, however, it may be better to extrapolate the liquid behavior. Extensive testing of this hypothesis has not been done. 

Often empirical models or correlative equations of state are used to describe the PVT behavior of polymers (Zoller, 1989). Such correlations are useful in the interpolation and extrapolation of data to the conditions of interest. When an equation of state based on statistical mechanical theory is used to correlate the data, the resulting equation parameters can also be used in mixing rules to determine the properties of polymer solutions. 

The High-Danner equation of state given in Section 3E can be used to predict the specific volume of polymers. Parekh (1991) has modified some of the reference volumes in the model to improve the model s accuracy for pure polymer volumes. The deviations in these predictions are generally less than 2%. Additional work needs to be done to establish the reliability and to extend the applicability of the method. 

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