Effect of Interfacial Free Energy on the Heterogeneous Distribution of Oxidized Carbon Black in Polymer Blends

The effect of oxidation of carbon black (CB) on the heterogeneous distribution in polymer blends was examined. In three kinds of polymer blends, i.e., high density polyethylene (HDPE)/isotactic polypropylene (PP), PP/atactic poly(methyl methacrylate) (PMMA), and HDPE/PMMA, the heterogeneous distribution of CB and oxidized CB were observed. The heterogeneous distribution of fillers in a polymer blend matrix was mainly due to the difference in affinity of CB particles to each component of the polymer blend. In HDPE/PP blend, the dispersion state of oxidized CB was different from that of unoxidized CB. The dispersion states of the fillers in these samples were predicted qualitatively from the values of the wetting coefficient which were calculated from the interfacial free energies, and they were coincident with the observations by scanning (SEM) and transmission (TEM) electron microscopies.