Dispersion of Carbon-Nanotubes in a Polymer Matrix by a Visualization Analysis of Shear Flow

Abstract

The filler size in polymer composites has experienced a tremendous reduction, especially in nano-composite formulations. The physical properties of polymer composites are also strongly dominated by the dispersion conditions of the filler. In the case of nano-composites, break up of the agglomerated filler is an important factor for improvement of the properties.In our previous report, the dispersion conditions were explained by using total shear strain [γ·t] as the dominant dispersion parameter, and the optimum mixing conditions for the blending of polycarbonate (PC) and carbon-nanotubes(CNT) were determined.In this study, break up of agglomerated CNT (analysis of dispersion process) was observed by a visualization analysis of shear flow. CNT was used as the filler in a PC matrix as we reported previously. The minimum shear rate required to break up the agglomerated CNT was defined as “critical shear rate” [γ c]. “Critical shear rate” was observed in two steps of the break up of agglomerated CNT. Dispersion conditions by a visualization analysis of shear flow were explained in terms of total shear strain as performed in the previous report. At the same total shear strains, the shear rate [γ] had a greater effect on the dispersion conditions than the shear rate history time [t] in the PC/CNT material combination.