A perturbed hard-dimer chain equation of state for polymer melts

Abstract A simplified perturbed hard-sphere chain equation of state (PHSC EOS) has been previously employed for modeling the pressure–volume–temperature (PVT) properties of some polymer melts using Yukawa hard-chain (YHC) plus first-order perturbation theory. In the present work, the accuracy of previous model was improved by taking contributions arising from hard-dimers. Three pure-component parameters appear in the proposed EOS, which reflect the segment number, non-bonded segment–segment interaction energy, and segment size. These parameters were optimized for the representation of PVT data of 14 homopolymer melts. This work considered chains that interact through a range-parameter of Yukawa potential with l.8. The reliability of the improved model has been assessed by comparing the results with 1163 literature data points for specific volumes over temperature and pressure ranging from 293–603 K and zero up to 200 MPa. Our calculations on the specific volume of studied liquid polymers reproduce very accurately the literature data, the overall average absolute deviation (AAD) of the calculated specific volumes from the literature data was found to be 0.48%. Moreover, our computation results have been compared with other works in the literature. This work showed that, addition of contributions arises from hard-dimers to YHC leads to the more accurate model than that previously applied to the polymer melts.