SUMMARY

Three types of CNTs were synthesized to elicit samples with distinct morphologies, all of which were subjected to identical in-situ flat punch nanoindentation tests. The density, tortuosity, and entanglement were found to represent three key factors governing the overall mechanical response of the CNT forests to local compressive loading. All CNT forests undergo an initial instability manifested as the formation of a buckle. These local buckles that determine a major part of deformation mechanism of CNT forests form at the location of best combination of low density, aligned CNTs, and less entangled CNTs along the height. This study provides insights into establishing a link between the differences in the density, alignment, and entanglement along CNT forest height and the distinct deformation mechanisms, which suggest that new synthesis methods could be developed to control CNT forest morphology and tailor the mechanical response to suit the needs of specific applications. I propose to perform nanoindentation on CNT forests coated on the top or along the height to measure their stiffness and recoverability. This study will help to understand the effect of the change of the mechanical constraints and the properties of individual nanotubes by coating. Finally, I propose a study of the effect of morphology change along the height and also the coating of CNTs on the adhesion of CNTs to the substrate which is an important strength property of CNT forests when used as grown on the substrate.