In the elements of aviation structures of large size and low rigidity rubber thermal protective coatings are used, which do not collapse when the structure is deformed. The use of rubber for supersonic aircraft and spacecraft is limited due to high requirements for heat and frost resistance of materials, as well as to their stability under the conditions of radiation and in a vacuum. Therefore, the development of new rubber with improved characteristics is an urgent problem. Multiwall carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. Carbon nanotube aspect ratio of length to diameter is more than 10 3 ; this distinguishes it from other nanoparticles. New composites with carbon nanotubes (CNTs) as additives were studied intensively during the last decade. Composites are characterized by extremely high specific strength properties, electrical and thermal conductivity. The effect of multiwalled carbon nanotubes on the performance characteristics of rubbers based on nitrile-butadiene was studied with various methods of their preliminary treatment and introduction into the composition of rubbers. It was shown that the introduction of 0.5-1.0 wt. % сarbon nanotubes into elastomers of different chemical structures leads to an increase in their physic mechanical characteristics, wear resistance and aging resistance, which significantly increases the service life of such products.
It is given the description of expanded graphite (EG) as a cluster-assembled nanoscale system. It is shown that in the structure of EG there are both extended defects formed by the convolution of one or more graphene layers and orientation defects-disclination. The strength characteristics of EG compacted materials can be controlled by changing the parameters of the production process in a limited interval (the ratio of the amount of oxidizing agent, intercalant, with natural dispersed graphite, its particle size). The procedure for treating multiwalled carbon nanotubes (MW CNTs) with a solution of potassium dichromate in sulfuric acid was carried out according to the known technology of oxidation of natural graphite in order to obtain expandable graphite. It provides for the use of sulfuric acid as an intercalating agent and potassium dichromate (K 2 Cr 2 O 7) as an oxidizing agent. The aqueous dispersion of oxidized MW CNTs is stable over time: the average particle size is 50 nm; two fractions-from 20 to 100 nm, amount-99.9%, mass-10%; from 250 to 500 nm and amount of 0.1%, mass-90%; high polydispersity ranges from 0.35-0.4, that is, the particles are quite close to the spherical shape. Modification of CNTs by oxygen simultaneously with anodic oxidation of natural dispersed graphite allowed for the first time to create a carbon-carbon composite "EG-MW CNTs" with enhanced physical and mechanical characteristics without additional use of binders.
The process of obtaining of new biosorbents from apricot seed shells by oxidative-organosolvent processing in "acetic acid-hydrogen peroxide" medium has been studied. The structural and sorption properties of the materials obtained using physical and chemical methods were investigated. The effect of the reactants ratio in solution, as well as the duration of the modification process on the yield, content of cellulose, lignin, and mineral components and on sorption properties of the products was studied. The dependence between the mineral content and the adsorption pore volume was shown. The positive effect of hydrogen peroxide application in the process of modifying of plant waste on cellulose content was estimated. Increasing the duration of modification increases the contribution of oxidative transformation of lignin into soluble products and decreases the yield of the lignocelluloses' materials. The regularities of sorption of marker of low molecular weight toxins and non-steroidal anti-inflammatory drugs on obtained products were investigated. It has been found that the highest sorption capacity of obtained lignocelluloses' sorbents towards Methylene Blue and Sodium Diclofenac corresponds to the samples with polysaccharide content 60%. It has been also found that the sorption equilibrium occurs within 120 min of contact. The obtained results demonstrate the feasibility of application of such lignocelluloses' carriers in the production of prolonged action drugs.
We analyzed "semiconductor" model of the "polymer-CNTs" composite strengthening at 300 K and low (0.1-0.5) wt% CNTs concentration. Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. We investigated influence of vibration bonds on polymer crystallization and strengthening in composite films of polyethylenimine, polyamide, polypropylene and rubber with multiwall carbon nanotubes. IR absorbance maxima we evaluated after formation of composite "polyethylenimine-carbon nanotube" in the spectral area of the sp 3 hybridization bonds at the frequency of primary amino groups of polyethylenimine. High IR absorption in the spectral area of sp 3 hybridization bonds of polypropylene, polyamide-6 with carbon nanotubes is determined by γ ω (CН) and γ ω (CH 2) vibrations. We measured IR reflectance maxima of composite "rubber-carbon nanotube" in the spectral area of CH valence and deformation vibrations. The IR peak dependence on the carbon nanotube content corresponds to 1D Gaussian curve for the diffusion equation in the electric field between electrons of nanotubes and protons in polymer according to "semiconductor" model of the composite structuring. For our case of the long-acting hundreds nanometer interactions, the polymer crystallization depends on sp 3 CC bonds organization in the intrinsic electric field according to the semiconductor n-p model. Tensile strength for polyamide-6 composites at 0.25% CNTs increases 1.7 times and tensile deformation-2.3 times.
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