PREDICTION OF PVT PROPERTIES OF POLYMER MELTS WITH A NEW GROUP-CONTRIBUTION EQUATION OF STATE

A new group-contribution modified cell model equation of state (GCMCM EOS) has been developed to predict pressure-volume-temperature (PVT) p roperties of polymer melts. The equation uses monomer group contributi ons to estimate the characteristic parameters in the modified cell mod el (MCM EOS) proposed by Dee and Walsh [G.T. Dee, D.J. Walsh, Macromol ecules 21 (1988) 811-817] for polymer molecules. Three molecular param eters per group were determined for 20 different groups. Average predi ction error of specific volumes was 0.67% for 32 homopolymers and 1.01 % for 20 copolymers and blend polymers over a wide range of temperatur e (277-671 K) and pressure (0.1-200 MPa). The average prediction error of PVT by GCMCM EOS was less than half of that by Parekh and Danner [ V.S. Parekh, R.P. Danner, J. Polym. Sci., Part B 33 (1995) 395-402]. F urthermore, if one specific volume datum at atmospheric pressure is us ed, the average prediction error of PVT by GCMCM EOS could be reduced to 0.27% for the homopolymers and 0.34% for the copolymers and blend p olymers. (C) 1998 Elsevier Science B.V.