Viscous flow and structure of linear polymers

The viscosity of linear polymers obeys the logarithmic additivity rule. This is associated with the fact that the activation energy of the viscous flow within certain limits of parameters changes does not depend on temperature, stress, molecular weight, and content of active filler. The mechanism of viscous flow of linear polymers is associated with the reversible destruction of an unstable supramolecular structure typical of the polymers in the state of viscous flow. The effect of shear stress on the viscosity of linear polymers does not obey the Eyring equation. It is supposed that the effect of shear stress on viscosity is associated with the peculiar mechanism of the destruction of the supramolecular structure. At higher rates of viscous flow of the polymer, the activation energy can decrease as a result of the deep destruction of the supramolecular structure. This is a reversible process, as after removal of stress the supramolecular structure slowly reverts to its original state.     

Thermochemical aspects of interaction of polyimide composites with organic sorbents

Interaction of ITA-31 polyimide binder with a series of industrial sorbents based on styrene and vinylpyridine derivatives was studied.     

Relaxation spectra in polymers

Methods of determining the continuous and discrete relaxation spectra are analyzed with the object of choosing a characteristic describing the actual relaxation processes. It is shown that the discrete spectrum is a physically sounder characteristic and makes it possible to distinguish the most probable elementary relaxation processes. Problems of predicting the relaxation processes in real polymers can be simplified by using the discrete relaxation spectrum.Leningrad Branch, Scientific-Research Institute of the Rubber Industry. Translated from Mekhanika Polimerov, No. 1, pp. 151–154, January–February, 1973.     

Deformation behavior of a filled nitrile vulcanizate in various states of stress

On the basis of experimental data obtained in uniaxial and symmetrical and nonsymmetrical biaxial tension and pure shear, the deformation behavior of unfilled and filled butadiene-nitrile rubbers is described by means of the Bartenev-Khazanovich one-parameter high-elastic potential.Leningrad Branch of the Scientific-Research Institute of the Rubber Industry. Translated from Mekhanika Polimerov, No. 2, pp. 363–366, March–April, 1972.     

Lifetime and relaxation processes in solid polymers

The relationship between relaxation processes and the fracture of solid polymers is examined with reference to the example of repeat loading with recovery. An investigation of polymethyl methacrylate, KAST-V glass laminate, and a Finnish polyester glass-reinforced plastic has shown that this lifetime may be considerably (several orders) shorter than that at the same level of constant stress. This is attributed to the time dependence of the structure-sensitive coefficient in the lifetime equation and is illustrated by means of a model that includes a Regel' fracture element.Moscow Lenin State Pedagogical Institute, Problem Laboratory of Polymer Physics. Translated from Mekhanika Polimerov, No. 4, pp. 629–635, July–August, 1969.     

Effect of lubricating greases on rubber-metal sliding friction at high temperatures

The effect of sliding velocity and temperature on the lubricating action of greases has been investigated under constant and variable temperature conditions. The most important factor is the friction temperature. Two different temperature regions, separated by a change in the type of friction, have been detected. A method has been developed for evaluating the lubricating effect of greases.Scientific-Research Institute of the Rubber Industry, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 876–880, September–October, 1968.     

Theory of molecular-kinetic processes in glass melts

Various equations that characterize the molecular mobility in vitrifying liquids and the vitrification process are compared and analyzed. The Williams-Landel-Ferry equation is treated within the framework of the relaxation theory of vitrification, and its relationship with the equations of Bartenev and Shishkin is discussed. The Shishkin equation for the activation energy is derived on the basis of the hole theory of liquids and the concept of free volume. As a result, the empirical constants in the Williams-Landel-Ferry and Shishkin equations take on a simple physical meaning.Translated from Izvestiya VUZ. Fizika, Vol. 11, No. 11, pp. 93–101, November, 1968.