Dielectric Spectroscopy on Propylene Glycol/Poly(Vinyl Pyrrolidone) Solutions: Polymer and Solvent Dynamics in Hydrogen-Bonding Systems

摘要

The dielectric behavior of solvent-rich solutions of poly(vinyl pyrrolidone) in propylene glycol has been studied through broadband dielectric spectroscopy. Measurements covered a broad temperature range both in the liquid and the glassy state of the samples and concentrations from 0% to 60% wt. of poly(vinyl pyrrolidone). Two distinct glass transitions are observed dielectrically, evidencing decoupling of the segmental motion of PVP and the rotation of the propylene glycol molecules. The decoupling appears not to be full, since the dielectric strength data hint to a participation of propylene glycol molecules in the relaxation connected with the glass transition attributed to poly(vinyl pyrrolidone). Interactions between the two components are expressed through the concentration dependency of the relaxation times, as well as through the marked broadening of the propylene glycol relaxation.