Preparation and rheological characterization of poly(methyl methacrylate)/functionalized multi-walled carbon nanotubes composites

A method to synthesize poly(methyl methacrylate) (PMMA)-modified multi-walled carbon nanotubes (MWNTs) via emulsion polymerization under high shear is presented. The modification of PMMA on MWNT surfaces was confirmed by Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectra, transmission electron microscopy and thermogravimetric analysis. PMMA composites with MWNTs and PMMA-modified MWNTs were prepared through melt mixing, and their morphology and rheological behavior were investigated. PMMA/PMMA-modified MWNTs composites have the rheological percolation threshold of 1.5 wt% MWNTs, but PMMA/MWNTs composites have the rheological percolation threshold of 2.5 wt%. The difference in rheological percolation threshold is mainly attributed to the larger gap between nanotubes exited in the PMMA/PMMA-modified MWNTs composites.