Partielle spezifische refraktionen von polymethylmethacrylat und polystyrol. I. Einfluß verschiedener lösungsmittel

The partial specific refractions according to the formulae of LORENTZ -LORENZ , GLADSTONE -DALE , and EYKMAN , respectively, have been determined for poly-(methyl methacrylate) in the solvents acetone, ethylacetate, butylacetate, tetrahydrofurane, dioxane, chloroform, toluene, and benzene, and also for polystyrene in butanone, dioxane, toluene, and benzene. It is shown that these values, which were obtained from experimental data of the refractive index increment, the refractive index of solution, and the partial specific volume with an accuracy of ± 0.1% are not completely independent of solvent. The largest difference was 1.3% in LORENTZ -LORENZ refractios, whereas the EYKMAN refraction seems to the smallest extend sensible against influences of solvatation. It is discussed, whether these effects bear some systematic feature. With respect to light scattering measurements it should be noticed, that refractive index increments may have an error of up to several percents, if calculated from a specific refraction value in another solvent.