The theory of orientational drawing of linear amorphous polymers

On the basis of modern ideas on the structure of linear, amorphous polymers a model of a molecular, three-dimensional network with temporary cross-links and van der Waals interaction between the chains is presented. Using this model as a starting point, a differential equation for the deformation of a linear, amorphous polymer in the viscoelastic state is derived. The differential equation for the orientation of a linear, amorphous polymer, which describes the evolution of distribution functions for statistical segments, is obtained. Previously obtained results follow from this theory as special cases.V. I. Lenin State Pedagogic Institute, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1021–1028, November–December, 1974.     

Positronium atom in an ionic crystal

The Sommerfeld-Welker model of a hydrogen atom in a spherical, impenetrable force cavity is used to calculate the basic properties of positronium in an ionic crystal. The basic properties of positronium (the lifetime against 2- and 3-annihilation, the count rate of 3 coincidences, and the magnetic-quenching parameter) are found as functions of the radius of the spherical force cavity.Translated from Izvestiya VUZ. Fizika, No. 7, pp. 71–75, July, 1970.     

Effect of sliding velocity on area of real contact and on force of friction in high-elastic materials

The velocity dependence of the force of friction and the area of real contact of SKN-18, SKN-26, and SKN-40 rubbers has been simultaneously determined on an optical instrument. In the region of small sliding velocities the area of real contact is virtually independent of the sliding velocity, while the force of friction increases in proportion to the logarithm of the sliding velocity, in accordance with the molecular-kinetic theory of friction. At high sliding velocities a deviation in the velocity dependences of both quantities is observed. The constant of friction has been determined over the entire velocity range and the resulting velocity dependence is examined in molecular terms.Mekhanika Polimerov, Vol. 3, No. 2, pp. 309–311, 1967     

Kinematics of fragments from disintegrating pressure vessels

The disintegration of an elastoplastic vessel filled with high-pressure gas is experimentally investigated and a model of the process is proposed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 88–93, November–December, 1988.     

Investigation of the deformation of a rubbery network polymer (SKN-40) in various types of states of stress

From the experimental data on equilibrium uniaxial and nonsymmetrical and symmetrical biaxial tension and pure and mixed shear it follows that the deformation behavior of SKN-40 crosslinked butadiene-nitrile copolymer is more accurately described by the Bartenev-Khazanovich high-elastic potential. The potential of the classical statistical theory of high elasticity of network polymers does not describe different types of states of stress with the same value of the material constant.Lenin Moscow State Pedagogical Institute, Laboratory for Problems in Polymer Physics. Leningrad Branch of the Scientific-Research Institute of the Rubber Industry. Translated from Mekhanika Polimerov, No. 5, pp. 840–845, September–October, 1971.     

Formation of the true contact area between high-elastic materials and a hard smooth surface

The change in the true contact area between rubber and glass on passing from static to dynamic friction has been studied experimentally. The extent of this change depends on the applied normal load and the contact time. The change of friction force is determined by the conditions of formation of the true contact area under the action of normal and tangential forces.Mekhanika Polimerov, Vol. 2, No. 2, pp. 263–268, 1966     

Relaxation mechanisms in polymers

The various types of molecular-kinetic effects are examined and the place of relaxation processes among them is determined. The transitions in noncrystalline and crystalline polymers are classified in accordance with physical principles. The experimental results of a study of molecular mobility on a broad temperature interval are analyzed for bulk polymers with different effective chain stiffnesses. The importance of taking into account the various relaxation processes that develop in polymers used in different branches of technology is noted.     

Temperature dependence of the actual contact area and friction force of high-elasticity materials

An investigation of the temperature dependence of the actual contact area (under static conditions and during friction at a given sliding speed) of materials based on butadienenitrile rubber in a wide temperature interval is described. Measurements of the friction force were also made. It was established that the temperature dependence of the contact area is associated with corresponding changes in the elasticity modulus (nonequilibrium static modulus for contacts at rest and dynamic modulus for nonstationary contacts). The friction constant c decreases linearly with rising temperature and does not depend on the applied load.Mekhanika Polimerov, Vol. 3, No. 4, pp. 726–729, 1967