An Analytical Equation of State for Molten Polymers

An analytical equation of state (EOS) developed by Ihm-Song-Mason (ISM) has been applied to calculate some thermophysical properties of molten polymers including Poly (1-octene) (PO), Poly (vinyl methyl ether) (PVME), Poly (vinyl chloride) (PVC), and Poly (styrene) (PS). Three temperature-dependent parameters of the ISM EOS have been determined based on the alternative scaling constants, dispersive energy parameters between segments/monomers (ε) and segment diameter (σ). The ability of the proposed EOS has been checked by comparing the results with 547 literature data points for the specific volumes over temperature from 311-557 K and pressure ranging from 0.1 up to 200 MPa. The average absolute deviation (AAD) of the calculated specific volumes from literature data was found to be 0.47%. The isothermal compressibility coefficients, κT have also been predicted using ISM EOS. From 188 data points examined, the AAD of estimated κT was equal to 7.75%. Our calculations on the volumetric and thermodynamic properties of studied polymers reproduce the literature data with reasonably good accuracy.