In this report, we propose an experimental approach to determine the role of the epoxy-CNT interface on damping by designing two systems of composites which differ in the interfacial area. The composites are namely 'dispersed' and 'layered'. The CNTs were uniformly distributed in the epoxy matrix of the dispersed nanocomposites. Whereas, in the layered nanocomposite, a layer of CNT was sandwiched between two epoxy sheets. Image threshold technique was adopted to characterize the CNT spread area in the epoxy matrix. The epoxy-CNT interfacial area is assumed to be less than the CNT spread area due to the agglomeration of CNTs. The CNT spread area of dispersed nanocomposites was found to be 30 times higher than that of the layered composite. In addition to this, it is observed with microstructure analysis using scanning electron microscope and transmission electron microscope that the dispersed nanocomposites were comprised of more epoxy-CNT interfaces, and the layered nanocomposites have more CNT-CNT interfaces. At a particular CNT content, at the glass transition temperature, higher dynamic loss factor was characterized with dispersed nanocomposites. The energy dissipating nature of the epoxy-CNT and CNT-CNT interfaces were studied by analyzing the microstructural mechanisms of damping related to the system of composites dealt with this study. © 2019 IOP Publishing Ltd.