Prediction of volumetric behavior and glass transition temperature of polymers: a group contribution approach

A simple method is presented for the prediction of PVT behavior and glass t ransition temperature of polymers over an extended range of external temper atures and pressures from the knowledge of only the molecular structure of their repeating units. Scaling constants of the Lattice Fluid (LF) equation -of-state model of polymers are extracted using experimental PVT data. Firs t-order and second-order groups specific to polymers are identified in thei r repeating units. These groups can capture even fine structural difference s, thus, enabling more precise predictions. A list of these groups is prese nted along with their contribution to the above scaling constants and the f lex energy of the Gibbs-DiMarzio theory for glass transition. Once these pa rameters are known, the estimation of density and glass transition temperat ures of pure polymers is straightforward using the LF theory. The predicted values are in satisfactory agreement with the available experimental ones. (C) 2000 Elsevier Science B.V. All rights reserved.