Radial growth rate of spherulites in polypropylene/barium sulfate composites

The effect of barium sulfate (BaSO4) on the spherulite radial growth rates of isotactic polypropylene (PP) was studied by means of optical microscopy. The PP–BaSO4 interface was modified by treating the fillers with different couple agents. The addition of BaSO4 depresses the spherulite growth rate, and the effect is more dramatic when the interfacial interaction between the PP and BaSO4 was enhanced. The data were analyzed with the Lauritzen–Hoffmann secondary nucleation theory, and the results demonstrated that the enhanced PP–BaSO4 interaction promotes the particles to serve as physical crosslinking points, which hinder the movement of the polymer chains and results in a decrease of the pre-exponential factor, G0.