Dynamic modulus of elasticity and resistance to mechanical breakdown of individual polymers and their mixtures

It is shown that when polystyrene, polymethyl methacrylate, polyvinyl acetate, and an ultramicroheterogeneous mixture of polyvinyl acetate and polymethyl methacrylate are vibroground in the brittle state, the resistance of the system to mechanical breakdown is determined by its elastic properties.Moscow Technological Institute of the Wood Industry. Translated from Mekhanika Polimerov, No. 4, pp. 744–745, July–August, 1969.     

Effect of molecular mobility,state of stress,orientation, and plasticization on the temperature dependence of the mechanical properties of linear polymers

The temperature dependence of the breaking stress and ultimate creep strain has been investigated in relation to preorientation, plasticization, and state of stress for polymethyl methacrylate, high-pressure polyethylene, polystyrene, and polyvinyl alcohol. The results of the mechanical tests are compared with the NMR data on the molecular mobility. The causes of the observed effects are discussed.Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 1, pp. 30–35, January–February, 1971.     

Study of relaxation transitions in polymers in the presence of magnetic fields

Infrared spectroscopy in polarized light has been used to investigate specimens of polyvinyl chloride exposed to a magnetic field. It is shown that, depending on the conditions of heat treatment, various conformational transitions of the C-Cl bond occur in the polyvinyl chloride. The orientation effects in PVC exposed to a magnetic field are associated with the preferential formation of trans isomers of the C-Cl bond.Sumgait Branch, Mamedaliev Institute of Petrochemical Processes, Academy of Sciences of the Azerbaidzhan SSR. Translated from Mekhanika Polimerov, No. 5, pp. 923–925, September–October, 1972.     

Intensity of mechanical action and mechanical degradation of rigid polymers

The authors have investigated the relation between the degradation of rigid carbon-chain polystyrene, polyvinyl acetate, and polymethyl methacrylate polymers with the kinetics of mechanical degradation during vibromilling. They determine the critical value of the intensity necessary for the onset of the degradation process.Moscow Technological Institute of Light Industry. Translated from Mekhanika Polimerov, No. 2, pp. 362–364, March–April, 1974.     

The acoustic properties of polymers with an asymmetric potential barrier at liquid-helium temperatures

The pulse-phase compensation method has been used to measure the propagation velocities of longitudinal and shear waves in polyvinyl chloride, polyvinyl fluoride, and polystyrene at frequencies of 1 and 5 MHz on the temperature interval 2.1–240°K. It has been established that as the temperature falls to 2.1°K the speed of ultrasound in these polymers monotonically increases, the dispersion (frequency dependence) of the speed of sound being preserved over the entire temperature interval. Two possible causes of the viscoelastic relaxation observed in the investigated polymers in the region of helium temperatures are considered.Scientific-Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 749–751, July–August, 1973.     

Problems of adhesive contact. A review

Questions of importance to the understanding of the adhesion mechanism are examined. Special attention is given to the relief of the substrate surface and processes associated with the penetration of the adhesive into surface depressions. The possibility of diffusion of macromolecules across the adhesive-substrate interface is considered; the importance of a little-studied factor — the diffusion of low-molecular substances — is demonstrated.V. I. Lenin All-Union Electrical Engineering Institute, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 840–849, September–October, 1969.     

Physicomechanical properties of elastomers in binary and ternary systems

A study was made of the physicomechanical and thermophysical properties of elastomers in binary and ternary systems consisting of polyamide, polyvinyl chloride, and rubber in various proportions. Binary and ternary systems with optimal physical and mechanical properties were selected from the composition-property diagrams for engineering applications. It was found that at a given ratio of polyvinyl chloride and SKN-40 rubber there is a nonmonotonic change in the physicochemical properties of films caused, apparently, by chemical interaction. It was shown that the mechanical properties of polyamide can be stabilized against thermal aging by blending with binary systems.Mekhanika Polimerov, Vol. 1, No. 5, pp. 3–12, 1965     

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.     

Relaxation of polyvinylchloride compositions

The relaxation of polyvinyl chloride, stabilized by dibasic lead carbonate or lead stearate and plasticized by a small amount of diisooctyl phthalate, was investigated. It was found that the lead stabilizers and diisooctyl phthalate accelerate the relaxation processes in the polymer. There is a correlation between the rate of the relaxation processes and the glass-transition temperature.Higher Chemicotechnological Institute, Sofia. Translated from Mekhanika Polimerov, No. 5, pp. 916–919, September–October, 1972.     

Effect of stabilizing additives on the strength characteristics of rigid polyvinyl chloride

The authors studied the effect of some stabilizing additives on the strength and durability (static fatigue) of stiff polyvinyl chloride (PVC) under uniaxial tension. They found these stabilizers to exert a significant effect on the durability of the compositions under study.Tambov Institute of Chemical Engineering. Scientific-Research Institute of Chemicals for Polymer Materials, Tambov. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 550–552, May–June, 1973.     

Methods of analyzing the results of long-time strength tests on synthetic materials

This article examines the deviations of Zhurkov's long-time strength equation, obtained in processing test results, from experimental data with reference to the example of polyvinyl chloride film. As a possible approximation an inverse linear dependence of the coefficient on temperature is proposed which makes it possible to obtain close agreement with experiment and complete information on the long-time strength of a polymer material from tests at two temperatures.Mekhanika Polimerov, Vol. 1, No. 6, pp. 92–97, 1965     

Long-term strength of rigid polyvinyl chloride in the flat stressed state

On the basis of experimental studies it has been established that the time to failure of rigid polyvinyl chloride depends basically on the magnitude of the largest stretching stress and at a long duration of testing deviates considerably from the exponential dependence. A refined formula is suggested for calculating the time to failure, which takes into account some characteristics of the stressed state.A. A. Zhdanov Leningrad State University. Translated from Mekhanika Polimerov, No. 3, pp. 453–457, May–June, 1970.     

Modeling the temporal evolution of tokamak discharge

Time dependences of integral characteristics of a discharge are modeled — plasma current, inductor current, and currents in the control windings in the presence of a ferromagnet. The effect of the iron core is allowed for by introducing nonlinear mutual inductances in the system of electrical-engineering equations. The system is solved numerically. Some discharge scenarios for the T-15 device are calculated.Translated from Metody Matematicheskogo Modelirovaniya, Avtomatizatsiya Obrabotki Nablyudenii i Ikh Primeneniya, pp. 259–266, 1986.     

Lifetime of amorphous polymers under intermittent loading

The lifetimes of two types of amorphous polymers (polyvinyl chloride and plasticized epoxy resin) under intermittent loading have been investigated. It is established that the lifetime, determined without allowance for recovery time, is less than that under constant load. Under periodic loading at constant stress the lifetime varies with the loading regime. For each of the investigated polymers a lifetime minimum is observed at a certain duration of the loading and recovery periods.Higher Chemical Technology Institute, Sofia. Translated from Mikhanika Polimerov, No. 5, pp. 912–916, September–October, 1971.     

Hardness of polymers

Hardness was measured on a Rockwell type instrument modified to measure the depth of the unrecovered indentation. The indentors were balls of various diameters and cones with various vertex angles. The hardness of the following materials was investigated: aminoplast (amino resin), K-17-2, FKP-1, polymethylmethacrylate (plexiglas), polyvinyl chloride (PVC), polyethylene, and teflon. The hardness is related to the strength and elastic characteristics.Mekhanika Polimerov, Vol. 2, No. 3, pp. 337–349, 1966     

Study of moisture absorption by an organoplastic

Conclusion A complex experimental study of the state of sorbed moisture in a unidirectionally reinforced organoplastic was conducted. The methods of TG, DSC, DTA, and NMR showed that moisture absorption in OP is reversible up to 8%, the sorbed moisture does not crystallize in the temperature range from –70 to 0 °C, it is finely dispersely distributed and is in the strongly and weakly bound state, and there is almost no free moisture. The results of the sorption experiments conducted on OP and its structural components: microplastic and EDT-10 binder, in a wide range of temperature-humidity conditions and the data from physical studies showed that moisture absorption in the materials basically takes place by diffusion and is satisfactorily described by a phenomenological model based on the Fick equation.A method of accelerated determination of the sorption characteristics of anisotropic composite materials was developed, using the introduced concept of the fictitious diffusion coefficient and the extrapolation method of determining the limiting moisture content. The features of migration of moisture on the interface in a multiphase system were investigated, and the possibility of successive calculation estimation of the sorption characteristics of an organoplastic at different structural levels was demonstrated: components—unidirectionally reinforced composite—model laminated article. The tested phenomenological model of the sorption process and the experimentally obtained values of the characteristics of the material were the basis for a method of calculation determination of the resource of moisture-proofing properties of a model multilayer article of CM in nonstationary external conditions.Translated from Mekhanika Kompozitnykh Materialov, No. 4, pp. 624–632, July–August, 1990.     

Local compatibility and the adhesion of polymers

The role of the thermodynamic factor in creating an adhesion bond between partly or wholly compatible polymers is discussed. The importance of this factor depends on the fact that polymers brought into contact will diffuse into each other only if they are wholly or partly mutually soluble. This mutual solubility is confined to a surface layer and is determined by the local diffusion. In considering the mechanism of formation of an adhesion bond between two polymers it is necessary to take their surface properties into account. In the diffusion theory of adhesion diffusion is regarded as the motive force in the creation of an adhesion bond.Moscow Lomonosov Institute of Fine Chemical Technology. Translated from Mekhanika Polimerov, No. 3, pp. 455–459, May–June, 1969.     

Measurement of the strength of plastics in high-speed compression

A previously developed [1] method of determining the strength of plastics in high-speed compression is extended to the temperature range –196° to +150°C. Dynamic strength data have been obtained for epoxy-polyester and polyvinyl butyral resins and glass-fabric reinforced plastics based on these resins in the indicated temperature range.Mekhanika Polimerov, Vol. 1, No. 5, pp. 34–38, 1965     

Derivation of quantum kinetic equation from the Liouville-von Neumann equation

A quantum Markov kinetic equation is derived from the Liouville—von Neumann equation in the framework of second-order kinetic perturbation theory. The proposed method can be used to obtain an equation that describes the quantum diffusion of a particle in a crystal.Moscow Aviation Institute. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 100, No.1, pp. 33–43, July, 1994.     

Unique Solvability of the Inverse Problem with a Time-Dependent Boundary Condition for a Sorption Model

A mixed initial boundary-value problem is considered for nonequilibrium sorption dynamics with inner-diffusion kinetics. The problem allows for convection and longitudinal diffusion and has a time-dependent boundary condition. This condition contains the time derivative of a solution component and constitutes the balance equation for the absorbed mixture near the output boundary of the sorption region—inside the diffusion barrier. Bounds on the solution of the direct problem are obtained: nonnegativity of the solution and its first time derivatives, and boundedness of the solution by known functions. The inverse problem of estimating the nonlinear system parameter—the sorption isotherm—is considered and a uniqueness theorem is proved.