A novel physicomechanical approach to dispersion of carbon nanotubes in polypropylene composites

A novel physicomechanical technique for the dispersion of carbon nanotube particles was proposed to fabricate the electrically conductive polymer composites in this study. The combination of dispersion agents such as superplasticizer and silica fume, ultrasonication, and melting processing method utilizing a solvent in the proposed technique was applied to improve the dispersion of carbon nanotube particles. Polypropylene and xylene were used as a binder material and as a solvent, respectively. The dispersion state of carbon nanotube particles in the xylene solution was estimated by the sedimentation and zeta potential tests, while that of carbon nanotube particles in polypropylene composites was evaluated by the electrical resistivity of the composites, Raman spectrum, and field-emission scanning electron microscopy images. The test results showed that the proposed technique significantly improved the dispersion of carbon nanotube particles in xylene solution, synergistically generating a physical shock to carbon nanotube agglomerates by the combination of silica fume and ultrasonication. The mechanism of the proposed technique for the dispersion of carbon nanotube particles was discussed. Furthermore, the electrical resistivity of polypropylene composites utilizing the proposed technique was significantly lower than that of polypropylene composites with carbon nanotubes measured in previous studies.