Antifrictional properties of compositions in the polyamide - copper system

Conclusion 1. The antifrictional properties of metallopolymer compositions made up by a thermal method in an air atmosphere (method A) and in a hydrogen atmosphere (method B), and also made up by mechanical mixing of P610 polyamide powders and PM grade copper (method C) have been investigated.2. It has been shown that the metallopolymer obtained by the thermal method in a hydrogen medium, at a degree of filling of 30% or more by wt., has less wear of the composition as compared with compositions made up by method C which are similar in degree of filling.3. Compositions made up by method A have a loosened structure and are comparable in wear resistance with the unfilled polymer.4. The coefficient of friction of the metallopolymer obtained in a hydrogen medium is less at the selected slippage regime than the coefficient of friction of the pure polyamide by a factor of 1.5, and is 20% less than that of the metal-filled composition made up by mechanical mixing in accordance with method C.5. It has been shown that the temperature on the friction surface of the metallopolymer made up by method B is less than that of the pure polyamide or the metal-filled composition made up by method C, by 40°C and by 20°C, respectively.Lenin Young Communist League. Riga Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, No. 6, pp. 1043–1048, November–December, 1978.     

Wear of glass-reinforced plastics in aggressive media

The effect of certain aggressive media on the wear of glass-reinforced plastics has been investigated. It is shown that as the angle of inclination of the glass reinforcing fibers relative to the friction surface increases, the wear of the material is sharply reduced.Ukrainian Agricultural Academy, Kiev. Translated from Mekhanika Polimerov, No. 2, pp. 364–366, March–April, 1974.     

Experimental investigation of the strength of structural plastics in multiple pulsed bending

Strip-beams of molded fabric-reinforced plastic, unidirectional wound glass-reinforced plastic, and polystyrene and syntactic foam have been tested in pulse bending in a modified electrodynamic testing device. The main stages of the failure process and the nature of the relation between the peak load and the number of cycles to failure have been established. For all the materials tested these relations are similar to the cyclic strength curves obtained at low loading rates. It is shown that for glass-reinforced plastics there is a correlation between the various stages of the failure process.Translated from Mekhanika Polimerov, No. 2, pp. 337–341, March–April, 1971.     

Preparation of fiberglass plastics by the method of curing under vacuum

A method of preparing fiberglass plastic articles using vacuum treatment in the curing process is considered. It has been established that the strength and deformation properties of fiberglass plastics so made improve greatly as the degree of vacuum is increased.Voroshilovgrad Engineering Institute. Translated from Mekhanika Polimerov No. 6, pp. 1128–1130, November–December, 1972.     

Calculation of frictional heat resistance characteristics

The search for self-lubricating materials, the selection of suitable ingredients and processing techniques for such materials, and quality control require the development of methods of testing for friction and wear. The frictional heat resistance can be used to evaluate the frictional properties of self-lubricating materials and to determine their limits of applicability. It is shown with reference to AF-3am self-lubricating material that it is possible to calculate the temperature dependence of the wear rate if the physicomechanical and geometric characteristics of the contact materials are known.Mekhanika Polimerov, Vol. 3, No. 3, pp. 524–532, 1967     

Predicting the porosity of glass-reinforced plastics from their thermal conductivity

The effect of porosity, reinforcement ratio and specific weight on the thermal conductivity of a series of glass-reinforced plastics has been investigated. It is shown that, if the thickness, the weight characteristic (weight per square meter), and the number of layers of reinforcing fabric are known and the thermal conductivities of the components are constant, then the porosity of the glass-reinforced plastic can be predicted from its thermal conductivity. Data on the relation between the specific weight and the thermal conductivity of the glass-reinforced plastics investigated are presented.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 522–525, May–June 1971.     

Effect of surface-active agents on the friction properties of polymers

The effect of surface-active agents on the friction properties of plastics has been investigated in relation to the example of an aqueous solution of alkyl phenol polyethylene glycol ether (OP-10) and polymethyl methacrylate. In the presence of a surface-active agent, as a result of adsorption plasticization, the deformation is localized in a thin plasticized layer without affecting the underlying layers of plastic.Moscow Lenin State Pedagogical Institute, Problem Laboratory of Polymer Physics. Translated from Mekhanika Polimerov, No. 5, pp. 927–929, September–October, 1970.     

Polymeric pairs having a low coefficient of friction

Results are given from studies on sets of pairs which have a coefficient of friction below 0.1 at medium specific loads and low rates of relative slippage. It is shown that this may be accomplished by using materials with different chemical structures in the pair, for example, Teflon and low-density polyethylene, or a self-lubricating material, for example oil-impregnated modified wood in a pair with a polymeric counterbody.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 933–935, September–October, 1973.     

Some laws of plastics friction

The dependence of the actual contact area S of plastics on temperature, specific load, and sliding speed has been investigated. The value of S increases exponentially with the specific load, the maximum value at large specific loads being less than the nominal contact area. The temperature dependence of S under static conditions between 20 and 130° C is attributable to the decrease in the static modulus of elasticity of the plastic near the glass transition point and to the development of high-elastic and plastic deformations at elevated temperatures. There is practically no change in S as the sliding speed varies from 10^–3 to 10 cm/min; at the same time the force of friction increases slightly.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1078–1081, 1967     

Effect of the surface activity of polymers during degradation on the friction and wear of plastic-metal and metal-metal pairs

The results of studies on the reasons why degradation products of polymers migrate into the metal and the metal is transferred into the plastic material during friction are discussed. Saturation of the steel surfaces with the degradation products of the polymers has been shown in the case of electropositive plastic counterbody, and decarbonization of steel surfaces in the case of the electronegative polymeric counterbody; a hypothesis has been put forward on the triboelectric and mechanochemical phenomena for the friction and wear processes of the plastic-metal and metal-metal pairs.Rostov-on-Don Institute of Railway Transport Engineers. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 520–525, May–June, 1973.     

Relationship between strength characteristics of unidirectional glass-reinforced plastics and their composition

The article discusses the effect of the amount of binder present and the porosity of the glass reinforced plastic on the usable strength of the glass fibers, the tensile strength, and the elasticity module in stretching. It is shown that a relationship exists over the whole range tested between the volume ratio of the components (binder and glass fiber), certain strength characteristics, and porosity. A method is suggested for the comparison of glass-reinforced plastics according to their usable fiber strength which can be used for the selection of the best binder, the glass material, the glass composition, glass fibers, the lubricant, the technological scheme, etc.Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 477–480, May–June, 1970.     

Deformative characteristics of plastics reinforced with high-modulus anisotropic fibers

The independent elastic constants of plastics unidirectionally reinforced with transversely isotropic fibers have been determined. It has been assumed that the distribution of reinforcement in a transverse section of the plastic is regularly rectangular or hexagonal. To determine the transverse elastic modulus and the shear modulus in the plane of reinforcement, a constancy-of-plane-sections hypothesis was used. Values of deformative characteristics determined by the assumed calculational dependences have been compared with the experimental ones for plastics reinforced with graphite fibers.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 631–639, July–August, 1972.     

Resistance to interlayer shear of plastics on a carbon filament base

Conclusions 1. An equation has been derived for the strength during interlayer shear along reinforcing fibers of a composite material of unidirectional texture which allows calculation of this index as a function of composition of the material and state of the interphase boundary. Experimental confirmation of this equation has shown that the effectiveness of surface treatment of the reinforcing filler can be estimated by its use.2. It has been shown that the strength during interlayer shear of an epoxy-phenol plastic can be increased by a factor of more than 3, and during bending by a factor of 1.3, as the result of treatment of high-modulus carbon fibers in nitric acid.3. A correlation has been established between changes in electrical resistivity of the carbon fiber and the molecular component of adhesion to it of consolidated epoxy-phenol binder.Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 445–451, May–June, 1977.     

Self-heating and failure of plastics under cyclic loading

It has been shown that plastics heated by cyclic deformation have two characteristic temperatures—a critical temperature T_hc, at which the most heavily stressed part of the test piece is intensely heated, and a temperature T_h, at which the test piece fails. The values T_hc and T_h are determined not only by the physicomechanical properties of the material, but also by the state of stress and strain, by the scale factor, and by the heat transfer conditions. It has likewise been shown that the form of the fatigue fracture surface of plastics is determined by the type of deformation and the temperature T_h.Mekhanika Polimerov, Vol. 3, No. 3, pp. 483–492, 1967     

Deformation of rigidly clamped specimens of acrylic plastics subjected to one-sided cyclic heating

The effect of one-sided rapid cyclic heating on the deformation of rigidly clamped specimens of acrylic plastics has been investigated. It is shown that as the temperature drop increases, so does the bending deformation (concave toward the heated surface) of the unclamped specimens; the greatest temperature change during thermal cycling is concentrated in an active surface layer not more than 1.6 mm thick and is accompanied by the development of tensile stresses in that layer. The characteristics of the reversibility of the deformation upon subsequent annealing are examined.Riga Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, No. 1, pp. 85–90, January–February, 1976.     

Mass-spectrometric investigation of solid lubricating coatings subjected to friction in a deep vacuum

The life of solid lubricating coatings of the VNII NP type, based on molybdenum disulfides and various binders, has been experimentally investigated under deep vacuum conditions (10^–8–5 · 10^–9 torr) together with the composition of the gas released in the friction process. It is shown that both under atmospheric conditions and in a deep vacuum the life of the coatings depends on the chemical nature of the film-former. The depth of the vacuum also has an important influence on the life of the coatings, both the mechanism and the end result of this effect depending to a large extent on the physicochemical properties of the bind. On the interval 10^–1–10^–2 torr there is a sudden change in the life of the coating.Physicotechnical Institute of Low Temperatures, Academy of Sciences of the Ukrainian SSR, Khar'kov. Translated from Mekhanika Polimerov, No. 6, pp. 1070–1075, November–December, 1970.     

Experimental evaluation of the strength anisotropy of a unidirectionally reinforced organic fiber-reinforced plastic

Conclusions The strength of a unidirectional organic fiber-reinforced plastic has been experimentally determined in various special cases of plane stress. An analysis of the data obtained shows that it is possible to describe the strength of the material in plane stress by means of a second-order surface equation containing linear and quadratic terms. The dependence of the strength in tension and compression on the angle between the directions of loading and reinforcement has been predicted and experimentally confirmed using the values found for the components of the strength surface tensors. The results of the study can be used to estimate the strength of multilayer organic fiber-reinforced plastics in cases where a unidirectionally reinforced layer can be taken as the basic structural element of the material.Translated from Mekhanika Kompozitnykh Materialov, No. 5, pp. 799–803, September–October, 1979.     

Investigation of the transfer process in polymer friction

It is shown that infrared spectroscopy can be used to investigate material transfer in external polymer friction. The kinetics of the process of transfer of Teflon to a polyethylene surface are examined and it is shown that the thickness of the transferred layer depends on the conditions under which the rubbing pair operates.Institute of Mechanics of Metal-Polymer Systems, Academy of Sciences of the Belorussian SSR, Gomel'. Translated from Mekhanika Polimerov, No. 4, pp. 750–752, July–August, 1971.     

Investigation of the effect of polymer coatings on wear under vibrational loads

The process of friction and wear in the presence of vibration has been investigated on the range of relatively high loads and vibration amplitudes. It is shown that the use of Teflon-based composites completely eliminates damage to the contact surfaces as a result of fretting corrosion.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1029–1035, November–December, 1973.     

Determination of the static strength of plastics from the elasticity and internal friction characteristics

It has been shown experimentally that the tensile or compressive strengths of various plastics on a broad temperature range can be estimated from the values of the dynamic modulus of elasticity and logarithmic decrement measured by a vibration method.All-Union Scientific-Research Institute of Aviation Materials, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 551–554, May–June, 1976.