Plasma treatment as a method for functionalising and improvingdispersion of carbon nanotubes in epoxy resins

This study reports on the results of plasmatreatedcarbon nanotubes (CNTs) in the presence of oxygenand ammonia which can be scaled up for relatively largequantities of nanomaterials. The plasma treatment has beenshown to change the surface chemistry and energy as wellas the morphology of the carbon nanotubes. X-ray photoelectronspectroscopy analysis shows increases in oxygenand nitrogen groups on the oxygen- and ammonia-treatedCNTs, respectively. Titration of the enhanced oxygenplasma-treated CNTs reveals an increased presence ofcarboxylic acid groups at 2.97 wt% whilst bulk densitydecreases from 151 kg/m3 for untreated carbon nanotubesto 76 kg/m3 after the enhanced oxygen treatment. The freesurface energy has also been shown to increase from 33.70up to 53.72 mJ/m2 determined using a capillary rise technique.The plasma-treated carbon nanotubes have beenmixed in epoxy and have shown an improvement in dispersion,which was quantitatively evaluated using anoptical coherence tomography (OCT) technique shown tobe suitable for nanocomposite characterisation. Thisresearch has demonstrated that it is possible to surfacefunctionalise large quantities of carbon nanotubes in asingle process, and that this process improves the dispersionof the carbon nanotubes in epoxy.