## 1 Introduction  
Carbon fiber reinforced plastic composites (CFRPs) have manifested their superior strength and stiffness capabilities in various industries, such as aerospace, civil infrastructure, and marine and automotive transformations [1; 2]. Most of these applications expose the CFRPs to loading and operating conditions that may induce vibrational oscillations. These motions are usually prominent around the natural frequencies of the system and often lead to structural damage and failure, and as such, cannot be ignored. Practically, the vibration attenuation can be carried out either passively or actively. Passive techniques use the intrinsic ability of certain materials to absorb the vibration energy (for example, via mechanical deformation in viscoelastic materials). Active methods employ sensors to attain the vibrations and actuators to suppress them in real time. Typically, these sensors and actuators are made of piezoelectric materials [3]. For fiber-reinforced composites (FRPs), vibration damping is achieved by embedding a viscoelastic matrix [4]. However, the mere addition of viscoelastic polymer lowers the strength and the modulus of the structure (per the rule of mixtures). Alternatively, in the stiffer phase, the fibers, can be tailored such that they contribute to vibration attenuation. Several approaches have been carried out to improve the fibers' damping capabilities, including fiber surface chemical functionalization, interlaminar interface improvement by adding metal particles, surface polymerization [5], adding carbon nanofibers [6], and viscoelastic polymer particles [7]. The discovery of carbon nanotubes (CNTs) in the late 1990s has invoked the idea of utilizing nano-additives to improve the interlaminar shear stress (ILSS) of CFRPs [8]. These allotropes of carbon possess exceptionally high aspect ratios, along with high thermal and electrical conductance [9; 10; 11; 12]. They can be grown on various substrates, including silicon and alumina [13; 14]. Despite their superior mechanical and transport properties, CNTs are prone to the problems associated with agglomeration [15; 16; 17; 18]. When dispersed in viscous media, they tend to form huge entangled colonies in random locations. [PERSON] et al. [19] studied this effect at the macro scale by fabricating two layer composites with different concentrations of CNTs. In addition to CNTs-enriched matrix, a CNT-rich sizing agent was also applied to the carbon fabric prior to the land layup vacuum bagging process used to make the composites. The results of tensile tests and fracture analysis revealed deterioration in the mechanical properties beyond certain concentrations of CNTs due to agglomeration [5; 20]. To mitigate agglomeration, several studies suggested functionalization of CNTs with various carboxyl, nitrile, or fluoride groups prior to their dispersion in any matrix [21]. These chemical groups allow CNTs to act hydrophobically, thus, improving their field emission characteristics and allowing fine-tuning of their electro chemical properties. [PERSON] et al. [22] conducted direct shear testing of epoxy thin films containing multi-walled carbon nanotubes (MWCNTs) and reported strong viscoelastic behavior with a 1400% increase in loss factor (damping ratio) over the baseline epoxy. [PERSON] et al. [23] employed MWCNT thin films as interlayers to reinforce the interfaces between composite plies, enhancing laminate stiffness and structural damping. The flat-wise bending tests of a piezosilica composite beam with an embedded nano-film sublayer indicated up to 200% increase in the damping level and 30% increase in the baseline bending stiffness. In this research, the CNTs were densely packed on a silicon substrate before being coated with epoxy. This treatment would bring significant damping, but fabrication could be costly and difficult. In addition, the weight % of CNTs is high in this case, which may not be economical. [PERSON] et al. [24] fabricated composites with randomly dispersed single-walled carbon nanotube (SWCNT) addition.