Distribution of Filler in Polymer Composites. Role of Particle Size and Concentration

The spatial distribution of filler particles and their agglomeration depending on concentration and size was studied. In all cases, silica particles served as filler. The particle size varied over a wide range, from nanoparticles to glass beads, and therefore the filler particles have the same nature. An amorphous polymer (polysulfone) and a crystallizing polymer (polypropylene) were chosen as a matrix for comparison. The filler concentration over the cross-section of the samples was determined visually and by electronic chemical analysis. It was shown that with increasing particle size, the tendency to redistribute the concentration increases in such a way that the near-wall region becomes depleted of filler. This effect is more pronounced for high filler concentrations and for a crystallizing polymer compared to an amorphous one.