Abstract
The migration of dye molecules and healing of structural heterogeneities (internal interfaces) in an amorphous-polymer-dye system during thermal treatment are studied for the PVC-Rhodamine 6G composite prepared via the method of solvent crazing. The kinetic data on the above processes are collected through spectroscopic measurements in the visible spectral region and parallel measurements of the linear dimensions of the samples. During thermal treatment at temperatures above T (g), dye molecules in the monomer modification migrate from the surface of the fibrillar craze material into the volume of the bulk polymer matrix; as a result, uniformly colored transparent samples form. In the general case, healing of the polymerdye composites includes two stages: a fast stage and a slow stage (similar to 1 and similar to 2000 min at 85A degrees C, respectively). The molecular mechanism of the first stage is related to the growth of the conformational entropy during shrinkage of the sample; as a result of this process, porosity decreases. The slow stage involves the disappearance of interfibrillar boundaries and occurs owing to the reptational mobility of macromolecules. The phenomenon of healing (in the broad meaning of this term) should be treated as a process that decreases the free surface energy of the polymer system.