The accelerated de-dispersion and sedimentation behaviors of multi walled carbon nanotube suspensions using surfactants

Multi walled carbon nanotubes (MWNTs) suspensions were prepared by using propylene glycol n-propyl ether (PnP), ethylene glycol monobutyl ether (EB) and propylene glycol monomethyl ether (PM) as solvents, copolymer Disperbyk-2012 (D-2012) and Disperbyk-198 (D-198) as surfactants associated with ultrasonication. The de-dispersion and sedimentation behaviors of suspensions were characterized by a step view centrifugation methodology which allows accelerating and quantifying the stability of dispersions in a direct way. During 1000 rpm accelerated centrifugation for 5600 s, PnP, EB and PM suspensions showed severe de-dispersion and sedimentation behaviors compared with that of surfactant suspensions, the sedimentation velocities of PnP, EB and PM dispersions were far more than that of surfactant suspensions. Both real time and statistic instability index analysis were performed and the results showed that PnP/D-198 and EB/D-198 were superior mediums for MWNTs suspensions, a plausible dispersing and stabilizing mechanism of the used surfactants and solvents for MWNTs was proposed.