This paper investigates the structure, length, and percentage of functional groups of multi-walled carbon nanotubes (CNT) depending on the time taken for functionalization in HNO3 and H2SO4 mixture. The carbon nanotube content and influence of functionalization time on mechanical properties of polymer composite materials based on epoxy matrix are studied. The extreme dependencies of mechanical properties of carbon nanotube functionalization time of polymer composites were established. The rise in tensile strength of obtained composites reaches 102% and elastic modulus reaches 227% as compared to that of unfilled polymer. The composites exhibited best mechanical properties by including carbon nanotube with 0.5 h functionalization time.

This research is devoted to the study of radar absorbing properties of the composites, based on the epoxy binder and carbon nanotubes (CNT) in the frequency range of 52-73 GHz. Three species of unmodified multi-walled CNT differing in length and diameter were investigated as fillers. The reflection coefficients (K refl) at the radar absorbing material (RAM)-air interface and the electromagnetic radiation (EMR) absorption coefficients (K abs) in the materials with the different content of nanotubes were measured (K refl and K abs were calculated using the highest (the worst) value of the voltage standing-wave ratio (VSWR) in the frequency range of 52-73 GHz). It was established that the increase in nanotubes aspect ratio (a ratio of CNT length to its diameter) leads to K abs rising for polymer composites. Also, CNT diameter decrease leads to K refl reduction. CNT of 8-15 nm in diameter and more than 2 μm in length are the most effective from all investigated fillers. The reflection loss values were calculated and CNT optimal concentrations were obtained at different thickness of RAMs.

No abstract

No abstract

No abstract