5-polymer processing and composites: Coarsening of PS/SAN blends with cocontinuous morphology studied with 3D image analysis

Geometrical parameters of the interface in fluorescently labeled polystyrene (FLPS)/styrene-ran-acrylonitrile compolymer (SAN) blends with cocontinuous morphology were obtained on the basis of differential geometry of 3D images. Images were analyzed for time evolution of interfacial area, average mean and Gaussian curvatures, curvature distributions and topology. Annealing of a symmetric (50/50 FLPS/SAN w/w) and a non symmetric (35/65) blend was monitored. For the symmetric blend a linear time evolution of the characteristic length along with a self similar growth of the microstructure, evidenced by the dynamic scaling of the curvature probability densities, were observed. For the non symmetric blend, the more elongated domains of the minor phase, namely FLPS, broke up producing zones with droplet-matrix structures coexisting with cocontinuous domains. Due to this morphological transition, dynamic scaling failed for the non symmetric blends. The number of holes on the interface, described by the genus, in a fixed sample volume decreases with time due to the growth of the microstructures and the formation of droplets.