Effect of Functionalization and Processing Parameters on SWNT Polypropylene Nanocomposites
Vinod K. Radhakrishnan and Virginia A. Davis. Department of Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, AL 36849
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. We report the influence of fabrication parameters on the properties of 0.5 % vol. SWNT and functionalized SWNT polypropylene (PP) (MFI = 12) nanocomposites fabricated by three different initial mixing methods. The nanotubes and PP were initially mixed by dry mixing, hot coagulation, or spray methods, followed by melt extrusion. Experiments were conducted to analyze the effect of mixing methods, extrusion conditions, and functional groups on the rheological and thermal properties of the nanocomposite. 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 results of the investigation show that initial dispersion of SWNTs in polypropylene has a large effect on the properties of the final nanocomposite.