Electrically conductive polymer nanocomposites of polymethylmethacrylate and carbon nanofibers prepared by chaotic mixing

Electrically conductive composites of poly(methyl methacrylate) and carbon nanofibers (CNF) were prepared in a low-shear chaotic mixer. These materials showed a percolation threshold of approximately 2 wt.% CNF compared to 6 wt.% for materials prepared in an internal mixer under comparable conditions of mean shear rate. It was found in materials prepared by chaotic mixing that nanofibers were pulled out of the bundles and oriented along the flow directions to produce electrically conductive networks. Electrical conductivity showed great sensitivity to mixing time around percolation threshold and remained almost unchanged with prolonged chaotic mixing above the percolation threshold. Thermal, thermo-mechanical and mechanical properties of the composites were investigated.