Electrical and rheological properties of double percolated poly(methyl methacrylate)/multiwalled carbon nanotube nanocomposites

Electrical and rheological properties of nanocomposites based on poly(methyl methacrylate) (PMMA) and multiwalled carbon nanotube (MWCNT) were studied from view points of double percolation by adding crosslinked methyl methacrylate-butadiene-styrene (MBS) copolymer particles to lower percolation threshold concentration of MWCNTs. It was found that the critical concentrations of MWCNTs for the percolation in the nanocomposites decrease and then increase with increasing the MBS contents of the nanocomposites. It is postulated that the addition of MBS at low concentrations results in double percolation of MWCNT and the significant decrease of critical concentration for the percolations. However, adding MBS particles in large amounts results in limited space for the distribution of MWCNTs and less efficient dispersion of the MWCNTs and the increase of the critical concentrations of MWCNTs for the percolations. Rheological properties and change of T(g)s reflect large interfacial areas in the well dispersed nanocomposite and were also interpreted to support the speculations for the effects of MBS contents and MWCNT concentrations of PMMA/MWCNT nanocomposites.