Partial specific volume and refractive index increment of polyvinylpyrrolidone in aqueous solutions: Temperature, concentration and wavelength dependence

The specific volume and the refractive index increment of aqueous solutions of polyvinylpyrrolidone were measured at temperatures from 25 to 35. Concentrations up to about 150 kg·m−3 were covered. The refractive index measurements were performed at 3 wavelengths, viz. 436, 546 and 578 nm. Our findings indicate that there is a sharp decrease in the partial specific volume of the polymer with increasing concentration above 100 kg·m3 and a corresponding increase in refractive index increment.