Abstract
According to the rotating disk method, the dissolution of polyvinylpyrrolidone (PVP) was investigated in acetone-water system to make an approach to an understanding of general dissolution behaviors of synthetic polymers. Three stages of dissolution were observed with the lapse of time, i.e., the initial, the main, and the final stages. The initial stage disappeared upon addition of NaCl in bulk solution. Only the main stage was explained according to Noyes-Nernst equation, and the activation energy of dissolution was close to the data reported for the diffusion controlled dissolution. The initial stage is considered to be concerned with the swelling process of PVP inducing the dissolution, and the final stage may be concerned with the coacervation of PVP. When NaCl was added in bulk solution, the initial stage seemed unessential for the dissolution of PVP, while the whole dissolution rate decreased. This was considered due to a suppression of the swelling of PVP on the surface of disk by the adsorption of Na+ on PVP.
