Measuring surface energy of carbon nanotubes using modified washburn method

In this study, the Washburn method and Owens and Wendt model were used to estimate the surface energy of an industrial grade multiwalled carbon nanotube (MWCNT) having a carbon purity of 90%. Identical MWCNT beds were prepared and tested using seven different solvents covering wide range of surface tensions and polarities. The solvents were water, diiodomethane, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), toluene, chloroform, and n-hexane. DMF showed the highest affinity towards the MWCNT. Therefore, it was used to determine the packing constant of the MWCNT beds assuming perfect wetting between the MWCNT and DMF. The contact angles between the solvents and MWCNT were fitted using the Owens and Wendt model to calculate the dispersive and polar components of the MWCNT surface energy. The test results showed that the surface energy of the 90% carbon pure MWCNT is 28.0 mJ/m(2) with dispersive and polar components of 23.1 mJ/m(2) and 4.9 mJ/m(2), respectively.