Effect of supermolecular structure on deformation and strength properties of low-pressure polyethylene

The effect of the supermolecular structure on the mechanical properties of polyethylene was studied. A change in the structure of films was achieved by varying the isothermal crystallization conditions. Films have been prepared from low-pressure polyethylene (LPPE) which have fine spherulitic and lamellar structures. It has been demonstrated that the strength of unorientated films with a fine spherulitic structure is twice that of unorientated lamellar specimens. This difference in the strengths was also retained after orientational elongation to 20 times the length at a high temperature (102°C). The conclusion was reached that the casting of LPPE plays an important part in preparing high-strength orientated polyethylene films.A. F. Ioffe Physicotechnic Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 6, pp. 963–966, November–December, 1972.     

Damage caused to polymer films by laser radiation and its relation to the nature and structure of the material

The experimental results of an investigation of the damage caused to polymer films by a free-running neodymium laser are described in relation to the nature and structure of the material. It is shown that the damage pattern is determined by the material structure.V. I. Lenin Tadzhik State University, Dushanbe. Translated from Mekhanika Polimerov, No. 6, pp. 1092–1093, November–December, 1971.     

Effect of modification on the structure and and mechanical properties of chlorosulfonated polyethylene films

Structure formation in chlorosulfonated polyethylene films is described. Modification with phenol-formaldehyde resin leads to a change in the supermolecular structures, which are stabilized by introducing 1% aluminum diisobutoxymonoacetoacetate into the system. It is shown that modifying the chlorosulfonated polyethylene leads to the formation of stable supermolecular structures and a considerable improvement in the mechanical properties of the films.State Scientific-Research and Planning Institute of the Paint and Varnish Industry, Moscow. Karpov Scientific-Research Physico-Chemical Institute. Riga Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 387–390, May–June, 1969.     

Action of a powerful light beam on polypropylene film

The changes in the supermolecular structure of polypropylene films exposed to powerful light pulses have been investigated by optical microscopy. A pulse lasting 10^–3 sec produces melting of the polymer with subsequent recrystallization and the formation of a finely spherulitic structure. In connection with the change in supermolecular structure there is an increase in the breaking stress of the melted portion of the film. A pulse lasting 2·10^–8 sec causes melting and vaporization of individual parts of the spherulites in the irradiated region. The remainder of the polymer is such that orientation of the structural elements with respect to the radius—the maltese cross pattern of the original spherulites—is preserved.Mekhanika Polimerov, Vol. 2, No. 6, pp. 817–822, 1966     

Influence of the solvent on the durability of cellulose acetate films formed from solutions

The authors examine the influence of the nature of the solvent on the time dependence of the strengths of films obtained from solutions of cellulose acetate in various solvents. They found that the durability of the films depends on the nature of the solvent. They have established that as the thermodynamic affinity of the solvent in the film-forming solutions gets worse, the durability of the films passes through a maximum; the nature of the solvent influences the parameter in the equation for the durability, which is responsible for changes in the structure of the polymer.V. I. Lenin Tadzhik State University, Dushanbe. A. M. Gor'kii Ural State University, Sverdlovsk. Translated from Mekhanika Polimerov, No. 2, pp. 360–362, March–April, 1974.     

A structural feature of the end region of a crack

The structure of the end regions of progressive cracks in polypropylene and polyethylene films with different supermolecular structures is examined. It is established that in the end region the opposite sides of the crack are connected by oriented polymer.Institute of Problems of Mechanics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 741–742, July–August, 1968.     

Investigation of the structure of carbon fibers by means of the scanning electron microscope

The structure of carbon fibers based on hydrated cellulose and polyacrylonitrile after heat treatment between 800 and 3000°C and of carbonized fibers based on polyacrylonitrile, submitted to oxidation in air, was investigated. It was established that significant changes in the surface structure occur after heat treatment at 2600°C and above. Structural changes in the carbonized fibers after various degrees of oxidation were demonstrated. Additional data were obtained on the change in the surface structure and the formation of a porous structure in carbon materials during oxidation under certain conditions.Translated from Mekhanika Polimerov, No. 5, pp. 925–926, September–October, 1972.     

Effect of structural changes in amorphous polymer films on the mechanical properties of coatings

The effect of structure formation on the mechanical properties of amorphous paint films has been investigated. It is shown that the organization of the supermolecular formations affects the internal stresses and adhesion of the film and, moreover, their tensile and impact strengths over a broad temperature interval. Fibrillar and "reticulate" structures give the best mechanical properties.State Scientific-Research and Planning Institute of the Paint Industry, Moscow. L. Ya. Karpov Physicochemical Institute, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 771–775, September–October, 1968.     

Relation between the internal stresses and the structure of polyacrylonitrile fibers

The change in the structure of a polyacrylonitrile fiber after various stages of processing has been investigated. The existence of three relaxation processes in isometrically heated polyacrylonitrile fibers is demonstrated.Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 943–945, September–October, 1968.     

Effect of an electron beam on the structure of epoxy resins

It is shown that exposing a cured epoxy resin to the action of an electron beam leads to a change in the structure outside the zone of direct action of the beam; this is accompanied by the formation of diffraction rings in the electron diffraction pattern and a change in microhardness.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 523–525, May–June, 1976.     

Some special features of the structural changes of epoxy resins under the action of magnetic fields

Conclusions 1. The action of a magnetic field leads to a change in the structure of an epoxy resin both at the molecular and at the supramolecular levels.2. A homogeneous magnetic field acting on the hardening process of an epoxy resin, due to the presence of the orientating moment, is able to produce ordered formations.3. A nonhomogeneous magnetic field results in a distribution of anisotropic morphological formations along the field gradient, promoting a change in the physicomechanical properties of the material.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 583–587, July–August, 1978.     

Analysis of the Adhesion and Adhesion Strength of Two-Layer Polymer Films and Coatings

The formation of adhesion bonds during the creation of two-layer polymer films and coatings capable of acid–base interaction is considered. The coatings are obtained from polymer solutions, and the second layer is formed from the polymer solutions and their mixtures on a hard polymer coating. As a result of absorption by the coating of a considerable amount of solvents (to 14%), polymer macrochains are able to approach one another at a distance necessary for the formation of acid–base (hydrogen) bonds and a transition layer. The polar component of the work of adhesion is equal to about 50% of the whole work W _a. There is no interrelation of the thermodynamic work W _a between the films and the work of their separation into layers. The main part of the external work upon the separation is spent (if strong donor–acceptor bonds are formed) for extracting the segments and macrochains of polymers out of the films.     

Some features of the frictional behavior of polymeric crystalline materials

The coefficients of friction for thin polymeric films are calculated, and it is shown that the coefficient of friction of the films is much less than that of a homogenous block. This may be due to some features of the antifriction properties of polymeric crystalline materials.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1053–1058, November–December, 1972.     

Effect of polymetaphenylene isophthalamide (phenylon) structure on the properties of an antifriction material

The relationship between phenylon structure and the friction properties of a phenylon-based material is established using the data of friction tests, x-ray analysis, and electron microscopy. It is shown that amorphization of the binder structure leads to a change in the coefficient of friction and to a displacement of the zone of maximum operating temperatures in the direction of higher values.Institute of Hetero-Organic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 201–206, March–April, 1969.     

Behavior of the supermolecular structure of oriented amorphous-crystalline polymers under cyclic loading

Equipment has been developed for investigating small-angle X-ray diffraction in various phases of the loading period in cyclically extended polymers. The behavior of the large-period structure of oriented polycaprolactam (kapron) films in cyclic extension has been studied. The results are compared with the data on the behavior of the same structure in static tests.Mekhanika Polimerov, Vol. 4, No. 2, pp. 195–199, 1968     

Mechanism of the increase in strength and heat resistance of oriented polymeric materials modified by graft copolymerization with vinyl monomers

The mechanical properties and structures of oriented films and fibers composed of polyethylene, polymethyl methacrylate, and other amorphous and crystalline polymers modified by the synthesis of uniformly distributed graft and block copolymers of methyl methacrylate, acrylonitrile, vinylidene chloride and other monomers have been the subject of a comparative investigation. The effect of the grafted polymers on the molecular mobility, relaxation processes, and solubility of the materials is explained by reference to a universal physical "crosslinking" mechanism. A theory of the interrelation between the structure and physical properties of the materials, the nature of the polymers, and the grafting conditions is developed and used to analyze the experimental data on a broad range of systems.V. I. Lenin Belorussian State University, Minsk. Translated from Mekhanika Polimerov, No. 6, pp. 968–975, November–December, 1973.     

Effect of structural changes on the sorptivity and mechanical properties of polyformaldehyde fibers

The dependence of the mechanical and sorption properties and structure of polyformaldehyde fibers on the degree of extension has been investigated. By x-ray structural analysis and sorption techniques it is shown that an increase in stretch ratio is accompanied by an increase in structural orientation with a simultaneous increase in porosity. It is established that the change in the mechanical properties associated with drawing depends both on orientation and on the presence of macrodefects in the fiber.Kiev Technological Institute of Light Industry. Translated from Mekhanika Polimerov, No. 6, pp. 1103–1106, November–December, 1971.     

Changes in the structure of polymeric materials in a magnetic field

It is shown that the action of a magnetic field leads to a change in the supermolecular structure of crystalline polymers. The creation of an oriented state in amorphous thermoplastics and thermosets is accompanied by an increase in their hardness and the homogeneity of the structural state.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 737–739, July–August, 1973.     

Experimental study of the effect of friction and bending on the strain distribution around the perimeter of a glass-reinforced plastic ring with unidirectional structure

The effect of friction and bending on the circumferential strain distribution in glass-reinforced plastic rings with unidirectional structure, stretched by two rigid half-disks, has been experimentally investigated. Strain distribution curves for rings of various thicknesses are given. The strain distribution at different levels over the thickness of the ring and the change in compressive strain along the radius have been studied.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 947–949, September–October, 1971.     

Functional approach to the periodic Anderson model

The method of functional integration is applied to the study of the behavior of the electron subsystem of adsorbed films with a regular structure. The effective action functional is calculated; equations for its parameters have been derived and investigated.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova, Akademii Nauk SSSR, Vol. 180, pp. 44–52, 1990.