Temperature dependence of the deformation properties of compositions based on polyethylene and polyisobutylene

The temperature dependence of the deformation properties (deformability and recoverability) of compositions based on low-density polyethylene and polyisobutylene has been investigated. For two-component polyethylene—polyisobutylene systems this dependence varies with the component ratio. Introducing a filler (talc) reduces the recoverability of the compositions owing to increases in both the delayed high-elastic deformation and the flowability. The deformation properties of compositions plasticized with paraffin change abruptly at the melting point of the latter.Moldavian Scientific-Research Institute of the Food Industry, Kishinev. Translated from Mekhanika Polimerov, No. 4, pp. 758–760, July–August, 1971.     

The optico-deformation effect in irradiated polyethylene

The absorption of light by polyethylene film subjected to extension and electron bombardment has been investigated on the wavelength interval 220–800 nm. It is shown that irradiation and illumination by a xenon lamp during extension reduce the stresses corresponding to the beginning of high-elastic deformation of the polyethylene. It is established that deformation and electron bombardment lead to an increase in the light absorption of the polyethylene film with absorption maxima at 245 and 290 nm. It is assumed that the nature of the effect is associated with reorientation of the macromolecule chains under the influence of mechanical stress and the appearance of allyl radicals-CH₂-CH CH-H-CH₂-.Institute of Physical Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 451–455, May–June, 1972.     

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.     

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.     

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.     

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.     

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.     

A comparison of the elastomeric properties of inorganic glasses and high polymers

The high-elastic properties and structural-mechanical characteristics of inorganic glasses and high-polymer materials are compared. Points of similarity and also differences in the mechanical behavior of organic and inorganic polymers in the high-elastic state are noted. Comparative estimates of the molecular weights of the chains in organic and inorganic polymer networks are given.Mekhanika Polimerov, Vol. 1, No. 3, pp. 21–28, 1965     

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.     

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.     

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.     

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     

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.     

A polymer film hardening effect

It is shown that a polyester film incapable of forced high-elastic deformation can be subjected to such deformation by stretching a film-substrate system. The resulting oriented structure is stable and on being measured from the substrate, the film exhibits a hardening effect. In this case contact with and adhesion to the substrate are a necessary condition for the development of the latent potential of the film.Lenin All-Union Electrical Engineering Institute, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 731–733, July–August, 1971.     

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     

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 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.     

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     

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     

Study of prefracture states of rigid polymers. 2. Elastic limit and strength

An explanation is offered for the relation between the magnitude of stresses at the elastic limit (strength) and the strains in rigid polymers. The possibility of high-elastic deformation and orienting processes, which have been considered in [1], is also explained here. Expressions are derived that relate the elastic limit to the strain, the modulus of elasticity, the coefficient of thermal expansion, and the Poisson ratio.For communication 1, see [1].A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 2, pp. 195–201, March–April, 1976.