Role Of Free Volume In Polymer Solution Thermodynamics

Abstract

The principal effects determining the value of the free energy of mixing of polymer solutions are discussed and compared, namely the combinatorial, energetic and structural effects. The influence of the last on the thermodynamic behaviour of polymer solutions is then dealt with, as revealed in the lower critical solution temperature, and in the effect of pressure on polymer-solvent compatibility, the second virial coefficient and the coil dimensions. Quantitative aspects of polymer solution thermodynamics are then discussed; arguments in favour of the use of the segment fraction (instead of the volume fraction) in expressing the combinatorial term are given, and the noncombinatorial contribution at zero pressure and the effect of pressure on the x parameter are characterized. Finally, a difficulty is noted in assessing the possible effect of a difference in diameter between polymer chains and solvent molecules or chains. © 1972, Walter de Gruyter. All rights reserved.