Dispersion of Calcium Carbonate Particle in Polypropylene Compound

The shape, size and rate of agglomerates in polypropylene (PP) filled with calcium carbonate (CaCO3) have been characterized by scanning electron microscopy (SEM), scanning acoustic microscopy and light scattering. Stearic acid was used as a modifier. PP and CaCO3 were mixed on a two-roll mill and thin films were prepared by compressing the mixed compound in a heated press.Using SEM images, the size and rate of agglomerates in PP/CaCO3 compounds were evaluated based on a binarization method. The rate of agglomerates (Diameter of equivalent circle>10μm) gradually decreased with mixing time. The degree of decrease of agglomerates in unmodified system was less than that of stearic acid modified system. Furthermore, the difference in particle size distributions of the agglomerates has been recognized for unmodified and stearic modified systems.The heterogeneous structure observed by scanning acoustic microscopy drastically decreased with mixing time and by modification of CaCO3. On the other hand, the radius of gyration from Guinier plot (light scattering) was not dependent on mixing time and modification of CaCO3.