Crystallization behavior of carbon black-filled polypropylene and polypropylene/epoxy composites

Effect of carbon fiber as secondary filler on the electrical, thermal and rheological properties of carbon fiber/polypropylene composites

In this study, hybrid composites based on carbon fiber (CF) and polypropylene (PP) were fabricated by melt mixing techniques. The composite with optimum fiber length (8 mm) was chosen as a reference material, and to it, CF of various lengths (6 mm, 100 μm, 60 μm and 100 nm) were added as secondary filler. To understand the synergism effect of these fibers, electrical, rheological, thermal and morphological properties of composites were studied. The surface resistivity of the neat PP is in the order of 1017 ohm/square. It is observed that surface resistivity of a single fiber filled composite is in the range of 104 ohm/square, while it further decreased by three-fold (101 ohm/square) in the case of secondary fiber filled composites, indicating that the electrical network remains intact. Thermal analysis shows variation in crystallization of hybrid composites that can correlate to the lengths of secondary fibers. The rheological analysis shows that the frequency dependence of storage modulus (G′) and loss modulus (G″) in the lower frequency region indicates an elastic solid like behavior of these composites. The morphological behavior showed that the CFs are well dispersed and form a good adhesion with the polymer matrix.