Modeling the volumetric properties of polymer melts using equation of state
A simplified procedure with minimum input information for predicting an analytical equation of state for polymer melts from temperature and liquid state density at the glass transition, as scaling constants, is presented. The second virial coefficients are calculated from a two-parameter corresponding states correlation, which is constructed with two constants as scaling parameters, i.e., the glass temperature Tg and molar density in glass transition ρg. This new correlation has been applied to the Tao-Mason equation of state to predict the volumetric behavior of polymer melts including polypropylene (a-PP), polyethylene oxide (PEO), polydimethylsiloxane (PDMS), poly styrene (PS), poly vinyl methyl ether (PVME), polycarbonate bisphenol-A (PC), poly butyl acrylate (PBA) and poly vinyl chloride (PVC) at compressed state with temperature range from 291.25 to 603.4 K and pressures up to 200 MPa. The experimental specific volumes were correlated satisfactorily with our procedure and average absolute deviation percent (AAD%) for 804 data point are within 0.34%.
Keywords: Equation of state, polymer melts, glass temperature, second virial coefficient.