Sh. Tuichiev

Structure, mechanical, and tribological characteristics of polyurethane modified with nanodiamonds

The effect of modifying additives based on detonation nanodiamonds on the tribological characteristics of polyurethane rubber is studied. Introduction of modifying additives based on detonation nanodiamonds (0.5 wt %) leads to a marked improvement in the antifriction and wear-resistance characteristics under conditions of boundary sliding friction for steel and for lubrication with water. The attained tribological characteristics (total energy loss for friction, weight loss of polymer during tribological contact, maximum admissible working pressure) are well (∼300%) above the corresponding characteristics of foreign analogs. Changes in the tribological characteristics of the formed nanocomposite material are observed, but the elastic and strength characteristics remain unchanged.

Microdeformational behavior of oriented semicrystalline polymers

Abstract A new experimental approach to the evaluation of microdeformational properties on the supermolecular level of highly oriented semicrystalline polymer is proposed. It is based on small-angle x-ray scattering measurements in situ during elastic and plastic tensile deformation of oriented samples along the orientation axes. The main idea of this approach consists of consideration of the competition of two processes occurring in uniaxial deformation: (1) intrafibrillar deformation of long periods; (2) mutual interfibrillar slip. A quantitative experimental criterion of inhomogeneity of intrafibrillar deformation is introduced. The combination of inhomogeneous fibril deformation and interfibrillar slip can explain all kinds of relationships between micro- (long period) and macrodeformations. The proposed approach was tested for several highly oriented polymer films and fibers.

Tribological characteristics of composites based on poly(tetrafluoroethylene) and fullerene carbon

The effect of fullerene carbon fillers on the antifriction characteristics and wear resistance of PTFE during its sliding friction on steel and water lubrication has been studied. The structures of the modified PTFE and the fullerence carbon filler are analyzed by small-angle and wide-angle X-ray diffraction. The hypothetical mechanism of reinforcing effect provided by the fullerene carbon filler during friction is proposed.

Effect of fullerene C60 on the structure and mechanical characteristics of polyethylene: Technological aspect

On the basis of the literature data, a retrospective analysis of the thermodynamic characteristics of dissolution of fullerene C60 in a series of single-ring aromatic solvents is presented. The effect of the molecular structure of a solvent on its dissolving capacity with respect to fullerene is studied. The parameter of the boiling temperature of the solvent normalized to its molecular mass is introduced. The correlation of this parameter with the dissolving capacity of the solvent is discussed. Special emphasis is placed on the effect of halogen-containing solvents on the dissolution of fullerene and indirectly on the development of the mechanical characteristics of films prepared from common solutions of fullerene and low-density polyethylene. For comparison, the films prepared from PE melts modified with low concentrations of fullerene are considered. The film structure is studied via X-ray analysis, optical microscopy, AFM, small-angle scattering of linearly polarized light, and DSC. The films with the maximum strength are prepared from solutions in halogen-containing solvents at a concentration of fullerene below 1 wt %. In this case, spherulites are 5–10 times smaller than those in the films cast from solutions in other solvents. In the films cast from common solutions of PE and fullerene in bromobenzene, crystal solvates C60 · 2C6H5Br are formed. It seems that the formation of the crystal solvates binds the residual solvent and thus affects the mechanical behavior of the films, thereby eliminating the plasticizing effect of residual bromobenzene. Localization of fullerene in various regions of the supramolecular structure of the films is discussed, and the morphology of the separating regions of the crystal solvate fullerene phase is analyzed.

Effect of C60 fullerene additions on the mechanical properties of a polybutadiene-styrene raw rubber

The effect of small C60 fullerene additions on the mechanical properties (upon uniaxial tension) and structure of a polybutadiene-styrene raw rubber is studied.

Step-Wise Concentration Influence of Fullerenes C60 and C70 on the Various Parameters of Condensed Systems

A step-wise changing concept is developed of the influence of fullerenes C60and C70 on various properties of condensed systems, liquid, and solid. In this, Part I is considered the step-wise character for three parameters: (1) the density of solutions; (2) the boiling points of solutions, and (3) the coefficient of the surface tension of solutions. The sharp drop of the density of solutions at very small fullerene concentrations is pointed out and considered. A step change in the coefficients of the surface tension of fullerene solutions with concentration were determined and are discussed. In Part II, to follow, the influence of fullerene concentrations on the freezing and melting of solutions will be considered.

Formation of Zero Density Regions During the Dissolving of C60 and C70

Based on a comprehensive review of the calculated and experimental data obtained in this and previous articles by the authors, a phenomenological model of the supramolecular structure of fullerene solutions is proposed. The model suggests the development in the fullerene solutions of some zero density regions due to poor packing of spheroidal fullerene molecules C60 and C70, on the one hand, and columnar or ribbon supramolecular structures formed by solvent molecules, on the other. It is assumed that the source of the long-range energy of fullerenes is a physical vacuum, concentrated not only in the cavities of the fullerene molecules but also in new regions forming outside the fullerenes during their dissolving in single-ring aromatic solvents.

Effect of fullerene C60 on the structure and mechanical properties of thin films based on poly(methylmethacrylate) and other carbochain vinyl polymers: A technological aspect

The effect of fullerene C60 on the structure and mechanical properties of poly(methyl methacrylate) films are studied via the methods of X-ray diffraction, mechanics, and optical and atomic-force microscopy. The findings of this study are verified with the use of the data obtained for amorphous and semicrystalline samples of other polymers, primarily carbochain polymers of the vinyl series, such as polyethylene, polypropylene, and polystyrene.

Effect of C60 fullerene additions on the thermal conductivity of low-density polyethylene films

The thermal conductivity of LDPE + C60 nanocomposites with a fullerene concentration up to 10 wt % is studied in the temperature range 20–80°C. This conductivity is found to nonlinearly decrease with increasing fullerene concentration. The decrease in the thermal conductivity of the composites is considered to be caused by a decrease in the phonon mean free path as a result of an increase in the number of scattering centers. The temperature dependence of the thermal conductivity is found to have a maximum.

Effect of fullerene C60 and γ radiation on mechanical properties and radiation resistance of low-density polyethylene

We analyze the joint effect of fullerene C60 admixtures and γ radiation from 60Co on the mechanical properties and radiation resistance of low-density polyethylene.