HSP study on the dispersion and interfacial adhesion of functionalized SWNTs in epoxy composites

Carbon nanotubes (CNTs) are considered as highly potential reinforcement material for the epoxy composites. However, the dispersion of CNT into epoxy is a big challenge due to the tiny scale and large aspect ratio. Surface functionalization is one of the ways that could change the compatibility between CNTs and epoxy matrix hence to change the dispersion of CNTs. The effect of functionalization was investigated by the XPS. The CNTs were dispersed in a solvent and mixed with the epoxy resin during the preparation of nanotube/epoxy composites, ultrasonic treatment and shear mixing is included to aid the dispersion. In this study, the compatibility of the CNTs with different functionalization and the polymer or the solvent is measured by using Hansen solubility parameters (HSP). The compatibility influences both the dispersion and the interfacial adhesion. The dispersion is tested by Dynamic Light Scattering (DLS) and light optical microscopy. The results of the dispersion of CNTs in epoxy are explained by HSP theory. The interfacial adhesion was evaluated using Raman spectroscopy and measuring the shift of the 2D band when applying a strain on the sample. Again the results are compared with the HSP results. This suggests an application of HSP to predict the properties of carbon nanotubes filled epoxy composite.