Dispersion State Study of Carbon Nanotube Epoxy Mixtures Using Linear and Nonlinear Rheology

Abstract

Carbon nanotube (CNT)-reinforced epoxy nanocomposites have attracted significant interest due to their potential applications in aerospace, electronics, and structural materials. To achieve the full potential of these nanocomposites, CNTs must be effectively dispersed within the epoxy matrix, as the dispersion state strongly influences network formation and overall material performance (1-3). Therefore, this study aims to provide a deeper understanding of the dispersion behavior of CNTs in epoxy resin through linear and nonlinear rheological characterizations. In this research, epoxy mixtures containing different concentrations of single-walled carbon nanotubes (SWCNTs) were prepared using tip sonication to evaluate the rheological percolation threshold through linear and nonlinear rheological measurements complemented by optical microscopy imaging. In addition, an electric field was applied to align the SWCNTs in the epoxy matrix. The results demonstrated that nanotube alignment reduced the percolation threshold, enabling the formation of an interconnected network at lower SWCNT concentrations. Furthermore, graphene oxide (GO) was incorporated into the SWCNT/epoxy systems to investigate the synergistic effects of combining one-dimensional (1D) and two-dimensional (2D) nanomaterials. Two SWCNT:GO ratios and two preparation methods were examined to evaluate their influence on the linear and nonlinear rheological behaviors of the mixtures. The results showed that nonlinear rheological analysis could distinguish between mixtures with similar linear rheological responses, highlighting its sensitivity to differences in nanofiller dispersion and microstructural development.