A GROUP-CONTRIBUTION ESTIMATION OF THE THERMODYNAMIC PROPERTIES OF POLYMERS

A simple method is presented for the estimation of the thermodynamic p roperties of polymers over extended ranges of external pressure and te mperature from a knowledge of the molecular structure of their repeati ng units. First-order and second-order groups are identified in the re peating unit which can capture even fine structural differences. A lis t of the most common such groups is presented along with their contrib utions to the scaling constants of the lattice-fluid equation-of-state model of polymers. Typical examples are given for the evaluation of t hese scaling constants of polymers. The accuracy of this calculation p ermits an estimation of the volumetric properties of polymers with an average absolute deviation from the experimental values of the order o f 1%. The method may be applied to any thermodyamic property that the equation-of-state model can calculate.