Deformation and sliding friction of polyurethane in the presence of a lubricant

The relation between coefficient of friction and elastic and high-elastic strains is investigated with reference to polyurethane subjected to friction in various liquid media. It is shown that a definite relationship between these parameters does exist. The effect of various liquids on the elastic and high-elastic deformation of polyurethane is studied.Kiev Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, Vol. 5, No. 2. pp. 357–359, March–April, 1969.     

Behavior in the transient regime of vibrating systems incorporating nonlinear spring-plastic shock absorbers

Combined spring-plastic shock absorbers, in which the part of load-bearing elements is played by springs while the plastic components with high internal friction provide for the intense absorption of vibration energy on passage through resonance, are subjected to a theoretical analysis. The model of the plastic component incorporates elastic and high-elastic elements connected in series, the high-elastic component of the total deformation being expressed by a fractional integration operator (see [5]).V. A. Kucherenko Central Scientific Research Institute of Building Structures, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1082–1088, November–December, 1973.     

Predicting the performance of extruded low-pressure polyethylene from rheological characterstics

Characteristic features of the high-elastic stalling of the melts of modern types of low-pressure polyethylene is investigated. The possibility of predicting the performance of polyethylene pipes from measurements of the following rheological characteristics is demonstrated: melt viscosity, shear-rate gradient at the outset of high-elastic stalling, swelling of the extrudate, and the amplitude of self-sustained fluctuations in shear stress.Kazan' State Technical University, Tatarstan, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 32, No. 4, pp. 558–563, July–August, 1996.     

Rheological properties of polymers in the fluid state

The possibilities and conditions of correlation are determined for the principal rheological characteristics of single-phase polymer systems measured for one-dimensional shear deformation in steady-state flow regimes, on transition from rest to steady-state flow, and in harmonic vibration regimes. Special significance attaches to the quantitative results of measuring the high-elastic properties of the polymer systems. It is shown that the Lodge theory, describing the flow behavior of high-elastic media, is well-founded in the linear region of deformation, i.e., for the limiting case of shear rates and shear stresses tending to zero, whereas the Mooney-Rivlin-Weissenberg theories are not in accord with the experimental data even in this limiting deformation regime.Topcheiv Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 1, pp. 164–181, January–February, 1969.     

Relaxation processes in oriented amorphous polymers

Values of the birefringence and high-elastic strain are presented for amorphous polystyrene subjected to stretching and annealing. The laws of the relaxation processes that occur in linear polymers under these conditions are discussed.Mekhanika Polimerov, Vol. 2, No. 3, pp. 323–329, 1966     

Effect of the physical state on tearing of amorphous polymers

On the assumption that the strength of linear amorphous polymers is determined by the efficiency of molecular interaction and the degree of orientation in a region adjacent to the tip of a tear, the temperature dependence of both indicated factors is described in the temperature range encompassing the rigid, high-elastic, and viscous flow states. On the basis of a comparison of the indicated temperature dependences, a -T curve for real polymers is proposed and confirmed by experiment. The dependence is characterized by a pronounced peak in the region of transition from the rigid state to the high-elastic state and is of exponential type in the temperature range encompassing this state.Mekhanika Polimerov, Vol. 1, No. 4, pp. 100–105, 1965     

Effect of liquid media on the deformation of the surface layers of a polymer-metal pair in sliding friction

The relation between the high-elastic component of polyurethane deformation and the deformation of the surface layers of metals has been investigated for sliding friction in various media. The surface layers of polymer and metal are plastically deformed. There is a certain correlation between the coefficient of friction and the amount of deformation.Kiev Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, No. 1, pp. 147–149, January–February, 1970.     

State of stress and strain of plates with two equal openings in the presence of high-elastic deformation

The apparatus of the nonlinear theory of elasticity [1–3] is used to investigate the high-elastic deformation of a plate with two equal circular openings and a massive block with two cylindrical channels. Computer-calculated stress concentration factors are given for compressible and incompressible materials.Translated from Mekhanika Polimerov, No. 4, pp. 687–692, July–August, 1969.     

Calculation of multilayer cylinders and disks composed of high-elastic polymer materials

The state of stress and strain of multilayer cylinders and disks composed of high-elastic materials is examined on the basis of the relations of the nonlinear theory of elasticity [2, 3].Mekhanika Polimerov, Vol. 3, No. 2, pp. 318–325, 1967     

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.     

Effect of hydrostatic pressure on the strength properties of polymer materials

On the assumption that the strength characteristics of homogeneous polymer materials depend on the specific volume, equations are derived for the dependence of the strength or high-elastic limit on the hydrostatic component of the stress tensor and temperature. The ultimate strengths in simple tension, compression and shear are considered in relation to brittle and plastic fracture.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 449–454, May–June, 1969.     

Surface instability of high-elastic materials

The problem of the surface instability of a lower half-plane in compression is investigated for an arbitrary form of the potential within the framework of the plane problem of the deformational stability of incompressible elastic bodies at finite subcritical strains [1, 4]. Numerical examples are considered for high-elastic bodies with potentials of the Mooney and Treloar types.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 1107–1110, November–December, 1970.     

Characteristics of stretching of high-impact polystyrene and polycarbonate close to the glass transition temperature

A study has been made of the stress-strain characteristics of high-impact composites based on poly sty renes (PS) or polycarbonates (PC) in uniaxial stretching at temperatures close to the glass transition temperature of the matrix material Heterogeneity of the structure of the material at the microlevel, owing to the presence of a graft copolymer in the PS composites or the presence of polyethylene terephthalate (a reactive additive) in the PC, tends to lower the effective glass transition temperature as determined at high elongations. Weak interaction of the impact-strength modifiers with the matrix material (determining the heterogeneity of the structure at the macrolevel) results in a lower stability of uniform stretching in the region of the high-elastic state, but increases the values of the elongation at break in the transition region from the glassy state to the high-elastic state. From the standpoint of achieving high strength and deformability of high-impact composites during their processing, the structure should be organized so as to provide optimal heterogeneity at both the microlevel and macrolevel.Translated from Mekhanika Kompozitnykh Materialov, Vol. 31, No. 4, pp. 509–517, July–August, 1995.     

A rheological model of polymers and glass-reinforced plastics

Network polymers and the corresponding glass-reinforced plastics are investigated for a homogeneous uniaxial state of stress and constant temperature. A physical law relating the high-elastic strain and the stress in explicit form with once-determined structural constants is obtained for the damped (bounded) creep regime. The theoretical solutions are compared with the experimental data for a glass-reinforced plastic based on unsaturated polyester resin and glass mat reinforcement.Institute of Engineering Mechanics, Bulgarian Academy of Sciences, Sofia. Translated from Mekhanika Polimerov, No. 5, pp. 851–857, September–October, 1971.     

Effect of deformation on the supermolecular structure of PN-1 copolymer

It is shown that under the combined influence of temperature and tensile stresses the spherical structure of crosslinked PN-1 copolymer becomes ellipsoidal. The change of shape is associated with the zone of high-elastic deformation.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 1129–1131, November–December, 1969.     

Effect of fillers on the structure and properties of cured resins

The elastic (modulus of elasticity and equilibrium high-elastic modulus) and thermal (volume coefficients of thermal expansion below and above the glass transition temperature) properties of compositions based on ÉD-5 epoxy resin cured with polyethylenepolyamine have been investigated. Quartz powder and aluminoborosilicate glass powder were employed as fillers at concentrations from 0 to 0.413. The thermal expansion coefficients of the compositions were studied in a dilatometer, in which the specimen is free of mechanical loads. The Young's modulus at 25°C and the equilibrium high-elastic modulus at 125°C of the compositions were determined in the compression regime in an instrument based on the IZV-2 optical length gage. The thermal expansion coefficients of the polymer matrix were calculated with allowance for the elastic properties of the resin and the filler. It is shown that, as the filler concentration increases, the thermal and elastic properties of the resin in the filled system change. This can be interpreted as a change in the properties of the resin as it approaches the surface of the filler particles. Increased interaction between the filler surface and the epoxy resin tends to stiffen the polymer network.Scientific Research Institute of Precision Technology, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1018–1022, November–December, 1969.     

Instability at the interface of bodies subjected to high-elastic deformations

The problem of instability at the interface of two elastic half-planes in compression is investigated within the framework of the plane problem of the stability of deformation of compressible and incompressible elastic bodies at finite subcritical strains [1, 2]. The results are obtained for the plane deformation of bodies with an arbitrary form of the elastic potential. Numerical examples are presented for high-elastic bodies with potentials of the Mooney and Treloar types.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 999–1002, November–December, 1971.     

Long-time strength of high-elastic polymers

This article examines the question of the inadequacy of the Zhurkov equation for describing the laws of long-time strength of polymers, loading of which is accompanied by the development of high-elastic or induced-elastic deformations. On the basis of general considerations concerning the deformation dependence of the stress concentration coefficient and orientation hardening of polymers, a more general relation between static fatigue life and long-time strength is proposed.Mekhanika Polimerov, Vol. 1, No. 6, pp. 85–91, 1965     

Freezing-in and relaxation of the elastooptical effect in transparent polymers

The behavior of typical transparent plastics, characterized by the birefringence under load, has been investigated experimentally on the interval of transition from the high-elastic to the glassy state during cooling. The optical effect, thus frozen-in, relaxes on heating above a certain temperature which is characteristic of a given material.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1110–1116, 1967     

Internal stresses associated with the swelling of ion-exchanger particles

The distribution of swelling stresses in a spherical ion-exchange resin particle is theoretically examined. It is established that the greatest stress occurs at the center of the particle and is proportional to the relative change of density at the particle surface and the high-elastic modulus of the ion exchanger. The time taken to reach the maximum stress at the center of the particle is also calculated.Mekhanika Polimerov, Vol. 3, No. 5, pp. 795–799, 1967