Микроволновые характеристики композитного материала на основе эпоксидного полимера с добавлением графеновых и ферритных наноматериалов

The radio absorption properties of polymer composite materials with ferrite and graphene additives in the microwave frequency range (26-38 GHz) were studied. It was shown that graphene-like structures have a significant effect on the ability of composite materials to shield from electromagnetic radiation.Проведены исследования взаимодействия электромагнитного излучения микроволнового диапазона с полимерными радиопоглощающими композитными материалами, содержащими наноразмерные ферритные и графеновые добавки. Установлено, что преимущественно слоистые графеновые структуры оказывают существенное влияние на способность композитных материалов к экранированию электромагнитного излучения данного спектрального диапазона

The use of carbon nanotubes to create materials that absorb electromagnetic radiation and electrodes of supercapacitors

Carbon nanotubes are effective nanomodifiers – providing the formation of a variety of thermal and electrophysical properties in composite materials. The functional purpose of composite materials determines the type and concentration of carbon nanostructures. The use of carbon nanostructures in polymer composites intended for electromagnetic shielding and electrode materials of supercapacitors is a promising direction in modern materials science. The method of manufacturing a radio-absorbing composite material included impregnation of a polyurethane foam billet – an aqueous composite suspension consisting of water, an acrylic copolymer, and carbon nanotubes "Taunit-MD". Structural studies of carbon nanotube samples were performed using transmission and scanning electron microscopy. To do this, PAM and SAM studies were performed using a HitachiH-800 electron microscope with an accelerating voltage of up to 200 Kev. For research purposes, electrodes with an area of 2 cm2 were made from carbon materials. Active mass was prepared from a carbon material and a binder, polivinildenftorid. Show PEM and SAM micrographs for samples of carbon nanotubes with the commercial name "Taunit-M". In this case, carbon nanotubes are characterized by smaller thicknesses in the range of 10-20 nm with a preferred average size of 12-15 nm. The structure of the tubes is very defective. The thickness of the tubes varies in some areas (not exceeding hundreds of nm) by more than 2 times. Carbon nanotubes have an irregular shape-there are processes, bends. The analysis of the obtained results allows us to conclude that the characteristic of the reflected EMI signal demonstrated by the pyramidal RPM is close in its values to that of the free space. At the same time, in comparison with the free space, there is a slight weakening (3-4) dB of the reflection coefficient. Carbon nanotubes MD has characteristics that exceed the carbon fabric "busofit" in terms of specific mass capacity, but inferior to it in terms of specific surface capacity. In addition, this advantage completely disappears at high current densities, which may be the result of a closed macrostructure and requires further optimization of the electrode manufacturing technolog

Aspects of the directional synthesis of carbon nanotubes to create hierarchical radio-absorbing composite materials

The conducted information review showed that there are various types of radio absorbing materials.  The expansion of the working wavelength range for radio-absorbing composites is possible due to the combined use of conductive fillers, characterized by different magnetic and dielectric characteristics and the value of electrical conductivity.  As a rule, the increase in the efficiency of radio absorption of materials is associated with an increase in the concentration of metal fillers in them, as a result of which the weight and size parameters increase proportionally.  To avoid this, the use of carbon nanomaterials, which have the ability to create self-organizing hierarchical structures in the bulk of the composite, allows.  Varying the composition of the catalytic systems of the CVD process allows directional synthesis of carbon nanomaterials with the necessary morphological characteristics.  To assess the effect of the composition of the catalyst on the morphology and structure of the synthesized CNTs, 3 Ni / MgO catalyst compositions with different contents of the active component (Ni) were selected.  The effectiveness of the obtained catalysts was determined by the specific yield of CNTs (gC/gkat).  The morphology and structure of the catalysts and the synthesized CNTs were studied by means of scanning by transmission electron microscopy. The use of a nickel-based catalyst provides the material with magnetic properties.  The diameter of carbon filiform formations synthesized on Ni/0.16MgO and Ni / 0.3MgO catalysts is ~ 30 ÷ 60 nm.  The Ni/0.5MgO system is characterized by low productivity in one-dimensional nanostructures; the sample after the CVD process contains a large number of unstructured forms of carbon and an unchanged catalyst.  Structural diversity in carbon nanomaterials allows to obtain on their basis an effective hierarchical structure in the radio absorbing composite.