The outstanding mechanical and thermal properties of single-walled carbon nanotubes (SWNTs) make them attractive reinforcing agents in fabricating the next generation composite. However, strong van der Waals attraction between the tubes results in the formation of aggregates leading to poor performance. Knowledge of the effect of fabrication parameters on the nanotubes dispersion and aggregate size is critical in manufacturing high performance nanocomposites. Our previous studies compared various pre-processing methods and showed that pre-processing along with extrusion conditions have a significant effect on the properties of melt extruded nanocomposites. In this study we focus solely on the effect of pre-processing parameters on the properties of the final nanocomposite.

We report the influence of fabrication parameters on the properties of 0.5 % vol. SWNT and functionalized SWNT polypropylene (MFI = 12) nanocomposites produced by mixing polypropylene in a mildly sonicated dispersion of SWNTs in chloroform followed by melt extrusion. Statistically designed experiments were employed to analyze the effect of polypropylene pellet size, sonication time and functional groups on the rheological and thermal properties of the nanocomposite. The level of SWNT dispersion was estimated by microscopy and Raman spectroscopy while TGA and DSC were used to observe variations in thermal properties. Rheological properties were investigated under controlled strain within the linear viscoelastic region of the nanocomposite. The results of the investigation show that initial dispersion of SWNTs in polypropylene has a large effect on the properties of the final nanocomposite.