Interfacial and hydrophobic evaluation of glass fiber/CNT–epoxy nanocomposites using electro-micromechanical technique and wettability test

Interfacial evaluation of glass fiber reinforced carbon nanotube (CNT)–epoxy nanocomposites and the hydrophobicity of CNT–epoxy nanocomposites were investigated by micromechanical and wettability tests. The contact resistance of the CNT–epoxy nanocomposites was measured using a gradient specimen, containing electrical contacts with gradually-increasing spacing. The contact resistance of CNT–epoxy nanocomposites could be better valuated by mainly the two-point method. Due to the presence of hydrophobic domains on the heterogeneous surface, the static contact angle of CNT–epoxy nanocomposites was about 120°, which was somewhat lower than that for super-hydrophobicity (>150°). For surface treated glass fiber, tensile strength decreased dramatically, whereas tensile modulus exhibited little change despite the presence of flaws on the etched fiber surface. The interfacial shear strength (IFSS) between the etched glass fiber and the CNT–epoxy nanocomposites increased due to enhanced surface energy and roughness. As thermodynamic work of energy, Wa increased, both the mechanical IFSS and the apparent modulus increased.