New insights into thermal conduction mechanisms of multi-walled carbon nanotube/ionic liquid suspensions

Abstract

Finely dispersed multi-walled carbon nanotube (MCNT)/ionic liquid suspensions spanning the dilute and semi-dilute regimes were prepared and their thermal conductivity (TC) was investigated. These suspensions showed remarkable TC enhancements only at a percolation concentration, i.e. 0.1 wt%, and at specific temperatures, indicating that the TC was both concentration and temperature dependent. Therefore, the results of the TC measurements demonstrated an interesting percolation thermal conduction phenomenon. Based on this, new insights into heat conduction mechanisms of MCNT/ionic liquid suspensions were proposed. At dilute concentration, the contribution of MCNT to the thermal conduction was negligible and base liquid played a dominant role. At or around percolation concentration, however, network structures of MCNT and temperature played synergistic effect. The former provided efficient thermal conduction paths and the latter dredged these paths. While at semi-dilute concentration, no marked TC enhancement was achieved due to the formation of MCNT aggregates.