Non-covalent functionalisation of carbon-based nanostructures and its application to carbon/epoxy composites

Abstract

This research goal is to investigate the surfactant effects on carbon/epoxy composites nano-modified by graphene and carbon nanotubes (CNTs). Multi-layered graphene (MLG) and multiwall carbon nanotubes were dispersed with two different surfactants, one ionic and another non-ionic, i.e., sodium dodecylbenzenesulfonate (SDBS) and polyoxyethylenenonylphenyl ether (IGEPAL® CO-890). The nanoscale analysis was based on morphological/nature observations via scanning electron microscopy (SEM) and atomic force microscopy (AFM), while the macro analysis follows the mechanical characterisation by tensile tests (ASTM D 3039) and three point bending test (ASTM D 790). The usage of surfactants as a strategy to improve the bonds between the nanostructures themselves, i.e., MLG and MWNT, and/or polymeric chains seems to be a viable option. However, in both cases, tensile and bending tests, the stiffness seems to be insensitive to non-covalent functionalised nanostructures. The ultimate strength, on the other hand, appears to be affected by the usage of surfactants (either CO890 or SDBS). The non-ionic CO890 surfactant seems to be more effective with MLG and pristine MWNT. In this case, for tensile tests the increase was close to 23.5%, while for bending tests an improvement of 11.4% was observed.