Effect of fullerene C<Subscript>60</Subscript> 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.     

Influence of fullerene C60 on the structure and mechanical properties of polyethylene

Influence of fullerene C₆₀ on the structure and mechanical properties of low-density polyethylene samples cast from a melt and a solution was studied.     

Stability and Stress State of an Underground Pipeline Joined to a Unit

International Applied Mechanics - The stability of a pipeline jointed to a unit interacting with the surrounding soil is analyzed. The pipeline is subject to axial compression. The stress state of...     

Inverse problem of determining the kernel in an integro-differential equation of parabolic type

We study the inverse problem of determining the multidimensional kernel of the integral term in a parabolic equation of second order. As additional information, the solution of the direct problem is given on the hyperplane x _n = 0. We prove a local existence and uniqueness theorem for the inverse problem.     

The structure of pediculidine

Summary A new alkaloid pediculidine, C₁₀H₉NO, mp 74–75°C, has been isolated from the ethereal fraction of the combined alkaloids ofP. olgae. Structure (I) has been proposed for the new alkaloid on the basis of its UV, IR, NMR, and mass spectra.Order of the Red Banner of Labor Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 304–306, May–June, 1971.     

Untersuchung der Änderung der übermolekularen Struktur von orientierten Filmen aus Polyäthylen niederer Dichte beim Reorientierungsprozeß

Ohne Zusammenfassung     

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.     

Transverse Vibrations of Buried Pipelines Under Axial Loading Within Geometrically Nonlinear Theory

International Applied Mechanics - The transverse motions of an underground pipeline located in water-saturated fine-grained soil are studied using the developed models of interaction in the...     

Quality Assessment of Wild and Cultivated Green Tea from Different Regions of China

Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term “wild tea” is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu’Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas.     

Viscoelastic characteristics of the interaction between structures and soils

The shear coefficients of a body relative to the soil and the shear creep and relaxation kernels are determined from the data of creep and relaxation tests.Urazbaev Institute of Mechanics and Earthquake Resistance of Structures, Academy of Sciences of the SSR, Tashkent. Translated from Mekhanika Polimerov, No. 2, pp. 207–211, March–April, 1973.