Multi-scaled carbon epoxy composites underwater immersion: A durability study

Abstract We study the effect of introducing different carbon fillers in epoxy, i.e. milled carbon and carbon nano tubes, separately and combined to produce binary and ternary composites with tailored properties. All specimens were immersed in water until saturation and subsequently tested using Dynamic Mechanical Analysis, Impedance Spectroscopy and Sliding Wear. The inclusion of carbonaceous fillers led to reduced water absorption with the overall absorption profile being mostly controlled by the matrix phase. The combined inclusion of carbonaceous fillers resulted in the optimal thermomechanical and electrical properties and the multi-scale reinforcement approach mitigated the detrimental effects of the hydrothermal exposure for the ternary composites. Wear resistance was heavily dependent on the employed filler, where MC composites exhibited the lowest mass loss rates. At the same time, the inclusion of the CNTs resulted in increased mass loss rates attributed to the weak interface between the matrix and the fillers. The multi-scale approach mitigated these phenomena maintaining the mass loss rates at intermediate levels. All obtained results indicate a synergy effect between the nano and micro scale thus providing an effective route towards epoxy composites with “tailor-to-demand” performance.