Adiabatic compressibilities of polymer solutions. Part. 1. Dilute solutions of cellulose nitrate

Adiabatic compressibilities of dilute solutions of cellulose nitrate, polyisobutene and polystyrene are obtained from measurements of sound velocity and density. Assuming solvent molecules concerned in solvation to be effectively incompressible, degrees of solvation are estimated from the adiabatic compressibilities of the solutions and solvents. Degrees of solvation of polyisobutene and polystyrene are very small. Those of cellulose nitrate are in general agreement, as regards order of magnitude, with those obtained by other methods and show a marked decrease with increasing molecular size of solvent. With solvents of smaller molecular size degrees of solvation exceed one solvent molecule per nitrate group and some attraction may be propagated from a first layer of firmly bound solvent molecules.