Effect of electron irradiation on the mechanical and thermal properties of some polymer materials

The effect of electron irradiation on the mechanical properties (deformability) of polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyimide (PI), and Fenilon (Fe) films, as well as the thermal properties (heat conductivity and capacity) of PTFE is studied experimentally. The thickness of the films was 40–50 m. Mechanical tests showed that polyimide films were more resistant to radiation than the other films. The investigation of the changes in the thermal properties of PTFE due to electron irradiation revealed that the phase transitions observed at temperatures of 293 and 303 K in unirradiated PTFE were shifted to lower temperature regions.Abai Alma-Ata State University, Kazakhstan. Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 5, pp. 683–689, 1998.     

Research on factors influencing the mechanical properties of metallic rubber

Starting from the theory of cellular solids, the nonlinear theory of dry friction, and the model of a bent slender beam, a nonlinear constitutive equation for a metallic rubber is constructed. The effect of density and shape factor on the mechanical properties of the metallic rubber is studied in the cases where varies only one of the parameters or both vary simultaneously. Static experiments were carried out in every case, and based on the results found, relations between the parameters and the corresponding nonlinear constitutive equation are constructed. If the density and shape factor of a metallic rubber are known, the coefficients of the equation can be obtained, and thus the constitutive equation itself of the rubber can be predicted.     

Some physical and mechanical properties of recycled polyurethane foam blends

Blends of secondary rigid polyurethane foams (RPUFs) with soft polyurethane foams (SPUFs) were investigated. The effect of SPUF content and its chemical nature on some physical and mechanical properties of the blends was evaluated. Owing to the stronger intermolecular interaction and higher values of cohesion energy, the blends of RPUFs with polyester SPUFs showed higher mechanical properties than those with polyether SPUFs. The density, hardness, ultimate strength, and the tensile, shear, and flexural moduli increased, while the impact toughness, ultimate elongation, and damping characteristics decreased with increasing RPUF content in the blends. Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 5, pp. 737–746, September–October, 2008.     

Dynamic mechanical properties of a heavily filled rubber

The acoustico-mechanical properties of a heavily filled rubber (70% by vol. NaCl) are investigated over a broad frequency-temperature interval. It is shown that there are various qualitative differences as compared with unfilled polymers. The effects of tensile strain and hydrostatic pressure on the dynamic properties of a heavily filled rubber are also determined.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 4, 688–692, July–August, 1968.     

Effect of mechanical factors on rubber wear in aggressive media

The effect of mechanical factors on rubber wear in aggressive slurries has been investigated. As the mechanical action becomes more intense, the effect of the aggressive medium increases. Rubber wear in an abrasive flow is a two-stage process: the aggressive medium modifies the surface layer, which is then worn away by the abrasive.Mekhanika Polimerov, Vol. 4, No. 3, pp. 499–503, 1968     

Effect of combined extrusion parameters on mechanical properties of basalt fiber-reinforced plastics based on polypropylene

Basalt fibers are efficient reinforcing fillers for polypropylene because they increase both the mechanical and the tribotechnical properties of composites. Basalt fibers can compete with traditional fillers (glass and asbestos fibers) of polypropylene with respect to technological, economic, and toxic properties. The effect of technological parameters of producing polypropylene-based basalt fiber-reinforced plastics (BFRPs) by combined extrusion on their mechanical properties has been investigated. The extrusion temperature was found to be the main parameter determining the mechanical properties of the BFRPs. With temperature growth from 180 to 240°C, the residual length of the basalt fibers in the composite, as well as the adhesive strength of the polymer-fiber system, increased, while the composite defectiveness decreased. The tensile strength and elastic modulus increased from 35 to 42 MPa and 3.2 to 4.2 GPa, respectively. At the same time, the growth in composite solidity led to its higher brittleness. Thus, a higher temperature of extrusion allows us to produce materials which can be subjected to tensile and bending loads, while the materials produced at a lower temperature of extrusion are impact stable. The effect of the gap size between the extruder body and moving disks on the mechanical properties of the BFRPs is less significant than that of temperature. An increase of the gap size from 2 to 8 mm improves the impregnation quality of the fibers, but the extruder productivity diminishes. The possibility of controling the properties of reinforced polypropylene by varying the technological parameters of combined extrusion is shown. The polypropylene-based BFRPs produced by the proposed method surpass the properties of glass and asbestos fiber-reinforced plastics.Submitted to the 10th International Conference on Mechanics of Composite Materials (Riga, April 20–23, 1998).Ukrainian State University of Chemical Technology, Dnepropetrovsk, Ukraine. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 6, pp. 845–850, November–December, 1997.     

Effect of powdered mineral fillers on the crosslinking of phenol-formaldehyde oligomers and the mechanical properties of the molding materials

By investigating the effect of various powdered oxides on network formation in phenolformaldehyde oligomers, it has been established that nonionogenic oxides increase the number of network defects in proportion to the surface energy of the powder. Small amounts of ionogenic oxides with a divalent cation cause the formation of new ionic or ionic-coordination linkages in the polymer network. The effect of mineral powders on polymer network formation is correlated with the mechanical properties of molding materials based on phenol-formaldehyde polymers with different network densities.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1033–1042, November–December, 1968.     

Antifriction and mechanical properties of polymer compositions based on silicone adhesives

A comparative investigation has been made of the antifriction and mechanical properties of polymer compositions based on K-400 silicone adhesive and fillers in the form of finely dispersed powdered polymers (tetrafluoroethylene, Kapron, polyethylene), graphite, sawdust, B-83 babbitt, and a lubricant^–US-2 grease. The antifriction properties of these materials are not inferior to those of some common nonferrous metals (B-83 babbitt, TsAM9-1.5 zinc alloy, OTsS5-5-5 bronze). The rational range of application of the compositions investigated is indicated.Rostov-on-Don Institute of Railroad Transport Engineers. Translated from Mekhanika Polimerov, No. 5, pp. 937–940, September–October, 1969.     

Effect of hydrostatic pressure on mechanical properties of plastics

The effect of hydrostatic pressure on the elastic and strength properties of plastics is investigated. Hydrostatic pressure is found to raise the modulus of elasticity, the tensile strength, and the elastic limit. Approximate equations for calculating the strength and elastic properties under various amounts of hydrostatic presure are proposed.Mekhanika polimerov, Vol. 1, No. 1, pp. 65–75, 1965     

Finite time blow-up and stability properties of materials with fading memory

A detailed analysis of the equations of nonlinear elasticity is carried out for a certain class of initial-boundary value problems. In particular, I examine whether the presence in the differential equation of a mechanical mechanism of dissipation is able to prevent instabilities and ensure global existence in time of the solutions.     

Identification of mechanical properties of composites based on design of experiments

A numerical-experimental method for the identification of mechanical properties of laminated polymeric composites from the experimental results is being developed. For the first time, it is proposed to use the method of experiment planning to solve the identification (inverse) problems. The basic idea of the approach is that simple mathematical models are determined only from information on the response of a structure in reference points of the design. Therefore, a significant reduction in the calculation of the identification functional (about 50–100 times) can be achieved in comparison with the conventional methods of minimization. Examples of the numerical identification of the elastic properties of the laminated composites from the measured eigenfrequencies of plates are discussed.Submitted to the 10th International Conference on Mechanics of Composite Materials, April 20–23, 1998, Riga, Latvia.Institute of Computer Analysis of Structures, Riga Technical University, Riga LV-1058 Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 1, pp. 3–16, January–February, 1998.     

Effect of temperature on the mechanical properties of boron fibers

The effect of exposure to temperatures on the interval 20–600°C for up to 1000 h on the physicomechanical properties of boron fibers at room temperature has been investigated. Prolonged exposure to temperatures up to 200°C does not have much effect on the mechanical characteristics of the fibers, whereas heating for one hour at 300–350°C increases the strength of the fibers by 10–12%.All-Union Scientific Research Institute of Aviation Materials, Moscow. Translated from Mekhanika Polimerov, No. 2, pp. 329–332, March–April, 1971.