CONCENTRATED-SOLUTIONS OF PERFLUOROPOLYOXYALKYLENE OLIGOMERS .2. VISCOSITY AND DENSITY IN POLAR-SOLVENTS

Viscosities and densities of two low molecular weight perfluoropolyoxy alkylene diols in 11 polar solvents are analysed. The specific volume- concentration behaviour shows the presence of an excess mixing volume common to all the solvents tested. Plots of viscosity data vs solvent volume fraction and solvent molar fraction are compared. This last cor relation allows a generalization of the phenomenology of concern, acco rding to peculiar solubility mechanisms mainly ruled by interactions b etween solvent and end units. The behaviour of a large number of diffe rent binary mixtures is consequently described by means of a few ''col lective'' relations which take into account changes in viscosity of so lutions due to the solvent choice.