The effect of choline-based ionic liquid on CNTs' arrangement in epoxy resin matrix

Abstract This work focuses on the effect of ionic liquids (ILs) on the arrangement of carbon nanotubes (CNTs) in CNTs–epoxy composites. Electrical conductivity experiments on epoxy–CNTs–ILs suggested that, compared to Ethaline, Oxaline and Reline, Glyceline had a more distinguishable effect on the CNTs' arrangement in the epoxy–CNTs–Glyceline (CG) composites based on scanning electron microscope results. The electrical conductivity of CG composites was improved by increasing the weight content of Glyceline up to 50 times that of CNTs (Gly/CNTs = 50), and for weight ratios higher than 50, a downward trend was observed. According to the proposed model, the increase in electrical conductivity seems to be a result of the formation of liquid vesicles which push the CNTs closer outside the Glyceline vesicles. Conversely, the drop in the electrical conductivity can be due to the enlargement of the vesicles, which dissolve CNTs and reduce their content in the epoxy. In addition, the tensile strength of CG composites increased by ratio of Gly/CNTs = 10 followed by a significant drop thereafter. Thermal stability of the CG composites was seen to decrease as Glyceline content is increased in the composite. This reduction was attributed to the early decomposition of Glyceline vesicles present inside the epoxy matrix.