Electrical Conductivity and Elastic Properties of MWCNT-PP Nanocomposites

Electrical and elastic properties of multiwalled carbon nanotubes (MWCNTs) reinforced polypropylene (PP) nanocomposites were studied experimentally and theoretically. The MWCNT-PP nanocomposites samples with a range of 0 to 12 wt% MWCNT were injection molded using different injection velocities. These nanocomposites were characterized for their electrical resistance using 2-Probe measurement and their tensile properties. Parallel to the experimental investigation, a percolation theory was applied to study the electrical conductivity of the nanocomposite system in terms of content of nanotubes and injection rate. Both Kirkpatrick [1] and McLachlan [2] models were used to determine the transition from low conductivity to high conductivity which designates as percolation threshold. Both experimental and modeling results have shown that the electrical conductivity increased suddenly as the content of MWNTs was close to percolation threshold of 3.8 wt%. The injection speed also showed an effect on electrical conductivity of the composites. In addition, several micromechanical models were applied to elucidate the elastic properties of the nanocomposites. The results indicate that the interphase between the carbon nanotubes and polymers plays an important role in determining elastic modulus of the system.