Electrical and Steady Shear Rheological Behaviour of Polypropylene Composites Reinforced with Single-Walled Carbon Nanotubes

The steady shear rheological behaviour, morphological, electrical, physical and mechanical properties of melt-blended polypropylene (PP)/single walled carbon nanotube (SWNT) were investigated. The rheological behaviour results indicated that both PP and its nanocomposites exhibited non-Newtonian behaviour. Addition of SWNT increased the shear stress and shear viscosity. It was also found that the materials experience a fluid-solid transition at 0.5 wt.% SWNT. The die swell behaviour increased with increasing shear rate and also decreased with the SWNT content. The morphology and degree of dispersion SWNT in the polypropylene matrix were investigated by SEM. The electrical percolation threshold was formed at about 1 wt.% of SWNT. In addition, a difference between electrical and rheological percolation thresholds was observed. DSC results confirmed the expected nucleate effect of SWNT on the crystallization process of polypropylene. It was also found that the tensile strength improved when 0.5 wt.% SWNT used. Furthermore, an increase in the tensile modulus was observed with increasing SWNT contents, but the elongation at break decreased.