Electret Materials Based on Fluoropolymers Modified with Vanadium- and Phosphorus-Containing Structures

Russian Journal of Applied Chemistry - Organo-inorganic composite materials based on films of polytetrafluoroethylene and tetrafluoroethylene–hexafluoropropylene copolymer, modified with...     

Influence of chemical composition of filler's surface on the burning of foam plastics

The influence of additives such as TiO₂, Al₂O₃ and their mechanical mixture as well as aluminium oxide, the surface of which contains phosphorous and titanium-oxide nanostructures, on the combustibility of foam plast (trade mark PEN-I), produced on the basis of epoxide novolak block-copolymers, was studied. It was stated that the incorporation both phosphorous-containing and titanium-containing oxides in the composition results in significant (in two to five times) decreasing of the samples’ combustibility. The probable mechanism of inhibition of burning process for those combustion retarders was discussed.     

Stability of the mechanical behavior of an arched TiNi strip under the conditions of the constrained shape memory effect

Unstable form changing (click) of an arched TiNi strip annealed at 773 K is investigated. After the annealing, the strip is placed into the grips of a deforming machine and is transferred to the martensitic state by bending in the direction opposite to its initial bend. Subsequent heating of the strip, which carries it to the austenitic state, is accompanied by a click under the conditions of constrained form changing. Analysis of the martensitic deformation in terms of the theory of diffuse martensitic transformations makes it possible to establish the conditions under which the form changing process becomes unstable.     

Thermal effects and anomalies in the low-temperature plasticity of crystals

This paper discusses theoretically the mechanism that causes the temperature dependences of the yield point and yield stress, along with their rate coefficients, to deviate from behavior characteristic of thermally activated plastic strain at low temperatures (<30 K). At this time the existence of such deviations, e.g., anomalous decreases in the values of these characteristics in this temperature range, is explained by arguing that the process whereby dislocations overcome local barriers has inertia. It is shown that the observed anomalies can be caused by the development of thermal instability in the plastic strain at low temperatures. In contrast to inertia-related effects, thermal effects allow us to explain the plasticity of crystals at low temperatures without contradiction and within the framework of a single mechanism, including the unstable, discontinuous character of plastic strain that is characteristic of these temperatures. Fiz. Tverd. Tela (St. Petersburg) 40, 684–689 (April 1998)     

Thermal Transformations of Titanium Oxochloride Nanostructures on Silica Surface

The nature of thermal transformations of titanium oxochloride surface groups on dispersed silica in the temperature range 25–600°C, both in the course of TiCl₄ chemisorption and in subsequent thermal treatments, is considered.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005, pp. 881–886.Original Russian Text Copyright © 2005 by Malkov, Sosnov, Malygin.     

The determination of the thermodynamic characteristics of Lennard-Jones fluids under isobaric conditions by the method of molecular functions

Integral equation theory for partial distribution functions was used to suggest an effective method for calculating the derivative of radial distribution function with respect to temperature under isobaric conditions. The thermodynamic expansion, compression, and pressure coefficients and isobaric and isochoric heat capacities were calculated for Lennard-Jones fluids. The calculation results were in close agreement with the known thermodynamic relations.     

Influence of chemical modification of the surface of polyethylene with phosphorus, boron, titanium, vanadium, and silicon halides on its vapor permeability

The influence of a gas-phase chemical modification of low-density polyethylene with volatile halides of various elements [PCl₃, TiCl₄, VOCl₃, BBr₃, and Si(CH₃)₂Cl₂] on the surface layer morphology and vapor permeability of polymeric formulations was examined by atomic-force microscopy, chemical analysis, and adsorption method.     

Synthesis and thermochemical transformations of vanadium oxychloride groups on a silica surface

Based on data from chemical analytical studies, IR, and Raman spectroscopy the relations between the conditions of synthesis, the structure of vanadium oxychloride groups formed on the surface in the interaction of VOCl₃ with OH groups of silica, and subsequent transformations in the composition of these groups during vapor-phase hydrolysis and heat treatment has been found.     

Influence of the grain size on the resistance of micro- and nanocrystalline metals against the neck-like localization of plastic deformation

The “high strength-low plasticity resource” dilemma associated with the macrolocalization of plastic deformation in the form of a neck in a stretched specimen, which leads to ductile failure of the specimen, has been theoretically discussed in the framework of the dislocation-kinetic approach. It has been quantitatively demonstrated using micro- and nanocrystalline metals as an example that their low plasticity resource (a small value of uniform strain before the beginning of the neck formation) and quasi-embrittlement result from the strong increase in the yield strength with a decrease in the grain size and the strain-hardening coefficient due to the annihilation of dislocations in the boundaries and bulk of grains.     

Generation and relaxation of reactive stresses in a Cu-Al-Ni shape memory alloy upon cyclic temperature variation in the range 293–800 K

The generation and relaxation of reactive stresses in Cu-Al-Ni shape-memory alloy single crystals studied during a single cycle of temperature variation in the range 293–800 K under conditions of the β-phase decomposition (above 600 K) are found to depend on the degree of β-austenite decomposition at the stage of decreasing temperature. The higher this degree, the lower the stresses relaxed and generated upon decreasing temperature and the higher the critical temperatures of the reverse martensitic transitions. Moreover, loading the alloy by reactive stresses during a heating half-cycle causes not only a reversible martensitic shape memory deformation but also an additional austenitic shape memory deformation to occur when the temperature is decreased.