The Effects of Functionalization, Preblending, and Melt Processing on SWNT-PP Nanocomposite Properties
V.K. Radhakrishnan, E.W. Davis, V.A. Davis
Auburn University, US
Keywords: carbon nanotubes, nanocomposites, melt processing, rheology
Abstract:Strong van der Waals attraction between single-walled carbon nanotubes (SWNTs) results in the formation of aggregates leading to poor performance when blended with polymers. Knowledge of the effect of fabrication parameters on the nanotubes dispersion and aggregate size is critical in manufacturing high performance polymer nanocomposites. We report the influence of sidewall functionalization, preblending, and processing conditions on the properties of 0.5 % vol. SWNT and functionalized SWNT polypropylene (PP) (MFI = 12) nanocomposites fabricated by three different preblending methods. The nanotubes and PP were initially mixed by dry mixing (DM), hot coagulation (HC), or spray coating methods (SM), followed by melt extrusion. The level of SWNT dispersion was estimated by microscopy, 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 HC melt extruded nanocomposite showed higher resistance to deformation, a more complex nanotube network, and better interfacial interaction with the polymer matrix than the other nanocomposites. The results of the investigation show that initial dispersion of SWNTs in polypropylene, and the processing conditions employed have a significant effect on the properties of the final nanocomposite.