The Interaction of Plasticizers and Polymers

The general problem of plasticizer compatibility is discussed, and it is suggested that a comparative measure of compatibility can be obtained from experiments which measure polymer-plasticizer interactions (w). Experiments are described which measure the viscosity of dilute polymer solutions in suitable mixed solvents containing the plasticizer in question. The slope of the ηsp/c−c curve is shown to be related to the equilibrium extent of swelling of the polymer in the pure plasticizer and, in general, the slope of the curve is a good comparative measure of the plasticizer's compatibility. The effects of temperature and composition of the mixed solvent are also discussed. The experiments are considered in the light of a previous theory of the effect of solvent on the ηsp/c ratio: the results do not support the suggested view that the slope of the ηsp/c−c curve is a simple linear function of w/kT.