ABSTRACT
When using clay llers, it is necessary to separate the particles into the right shape and layer structure which is called exfoliation. They need to be about 1 nm thin and 500 nm wide for achieving optimal gas permeability without affecting the optical quality. Particle orientation also has an effect on the success of a nanocomposite. Nanoparticles need to be dispersed throughout polymer so that they are parallel to the material’s surface. This position ensures a maximum torturous path for the gases when passing through the polymer. Compatibility between the nanollers and the polymer substrate may cause issues as well, depending on how they interact with each other. Certain nanollers need to be prepared so that they can perform well
with the substrate. Another concern is during the processing stage. There is a possibility of reaggregation where the particles clump together. At the same time, if it is subjected to force, there is a possibility of agglomerated nanoparticles getting split. Therefore, premature failure takes place in the nal product. The alignment of nanoparticles in the composite matrix is critical to maximize unidirectional properties such as strength and toughness. As in the case for traditional composites, it is even more challenging to determine the strength, composition, and functionality of the interfacial region. In addition to the composite integrity, the nature of the nanoparticle is also critical for property improvement. It is observed that single-walled nanotubes (SWNTs) are relatively defect-free whereas, multiwalled nanotubes (MWNTs) typically have more defects, such as topological defects (pentagon, heptagon) and structural defects (discontinuous, cone-shaped walls, or bamboo structure). To improve dispersion and compatibility in polymer matrices, nanotube is functionalized. There are still some concerns such as whether functionalization of a nanotube will affect the properties to improve the nal product. Scale-up is needed to produce large quantities of nanomaterials for manufacturing purposes. There is still a lack of real-time characterization methods, instrumentation, tools, as well as a lack of affordable infrastructure (facilities, equipment, design tools, skilled personnel). The mechanical and dispersion properties, and the alignment of nanotubes are mainly involved in enhancing the properties of nanotube/polymer composites. However, it is also hard to achieve this without a good interfacial bonding between nanotubes and matrix. It is yet to be established: (1) whether the chemical bonding between nanotubes and matrix exists or not and (2) do the nanotubes still maintain their extraordinary mechanical, electrical, and thermal properties if chemical bonding exists between the nanotube and the matrix?
