Influence of technological processing parameters on the properties of carbon filled thermoplastics

The effect of processing parameters of injection molding on the mechanical and tribotechnical properties of carbon plastics based on polyacetals is investigated. The copolymer of 1,3,5-trioxane with 1,3-dioxolane is used as the polymer matrix. Hydrated cellulose Ural LO-24 carbon fibers are used as the reinforcing filler. The effect of molding temperature, pressing time, and temperature of the casting mould on the properties of carbon plastics is investigated. It has been found that for improving the mechanical properties of carbon plastics it is necessary to raise the molding temperature up to 200–210°C. Prolongation of the technological cycle leads to thermal degradation of the polymer in the cylinder of a casting machine. The mould temperature only slightly affects the composite strength properties, but lower temperatures create better conditions for polymer crystallization. As a result of our investigations, the optimal processing parameters of the above carbon plastics are determined.Ukrainian State University of Chemical Technology, Dnepropetrovsk, Ukraine. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 3, pp. 385–392, 1999.     

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     

Use of plastics as model materials in the photoelastic method of stress analysis

The suitability of various plastics for use as model materials in the photoelastic method of stress analysis is briefly reviewed. The photoelastic properties of a series of optically sensitive plastics are examined. It is shown that the wide range of properties possessed by these materials makes them suitable for the photoelastic solution of various problems.Mekhanika Polimerov, Vol. 2, No. 3, pp. 440–445, 1966     

Special features of the effect of cellular structure on the mechanical properties of foamed plastics

On the basis of the cell model proposed the mechanical characteristics of high-density foamed plastics are calculated. Assuming the general application of the foaming mechanism and the formation of macrostructure, the principle of structural-mechanical superposition of foamed plastics is established. This enables the equivalence of changes in their strength and elastic properties to be indicated over a wide range of variation of the stiffness of the polymer base and the apparent density of the foamed material.Scientific-Research Institute for Synthetic Resins, Vladimirsk. Translated from Mekhanika Polimerov, No. 6, pp. 976–981, November–December, 1972.     

Effect of scale and temperature factors on the compressive and shear strengths of plastics

Results are given of investigations of certain strength characteristics of a number of thermosetting plastics in relation to the scale of specimens reduced to 1/5 the standard size, i. e., the effect of the scale factor on the mechanical characteristics of plastics in compression and shear. In addition, results of a study of the dependence of the mechanical characteristics of plastics on the degree of heating in the temperature range from 20 to 200°C, i. e., the effect of the temperature factor on these characteristics, are also given.Mekhanika Polimerov, Vol. 1, No. 4, pp. 92–99, 1965     

Prediction of the thermal conductivity of oriented fiberglass plastics

An analytical equation has been derived for calculating the thermal conductivity of fiberglass plastic pipes in the axial direction. The pipes, which represent items with the most general type of reinforcement, were manufactured by uninterrupted slanting and longitudinal-transverse winding. Equations for calculating the thermal conductivity of oriented fiberglass plastics with other types of reinforcement featuring various angles to the direction and plane of reinforcement are particular cases of the derived equation. The results of an experimental check for this equation for calculating the thermal conductivity of epoxy fiberglass plastics are presented.Translated from Mekhanika Kompozitnikh Materialov, Vol. 29, No. 3, pp. 381–386, May–June, 1993.     

The effect of glass fiber inelasticity on the long-term strength of reinforced plastics subject to uniaxial tension along the fibers

Relationships are presented for determining the long-term strength of reinforced plastics subject to uniaxial tension by a constant load directed along the fibers; these relationships are based on the rheological characteristics of the components of the plastics. The proposed expressions agree quite well with experiment. Treatment of the experimental data by mathematical statistics showed that the relative strain at fracture remains constant; it does not depend either on the relative reinforcement content or on the applied load (i. e., on the time to fracture).Mekhanika Polimerov, Vol. 3, No. 4, pp. 719–725, 1967     

Effect of porosity and component ratio on the thermal conductivity of glass-reinforced plastics

The dependence of the thermal conductivity of glass-reinforced plastics on porosity and component ratio is investigated. The possibility of determining the porosity, specific weight, and resin content of glass-reinforced plastics from their thermal conductivity is confirmed.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 487–491, May–June, 1969.     

Experimental study of thermal expansion of layered carbon-reinforced plastics

Conclusion The nonlinear dependence of the thermal deformations on the temperature for a wide class of layered carbon-reinforced plastics was experimentally demonstrated and the use of the thermal expansion function of the material instead of the corresponding characteristic: the thermal expansion coefficient, was substantiated in the present study. A method for determining the parameters of the thermal expansion functions was developed in consideration of their nonlinear dependence on the temperature and the numerical values were reported for layered carbon-reinforced plastics of two types with typical reinforcement schemes. In addition, the significant dependence of the thermal expansion functions on the geometry of the structure of the carbon-reinforced plastics was observed, and the major possibility of optimum planning of the structure of the material from considerations of geometric stability was demonstrated. The study of thermal deformations of reinforced plastics in consideration of their random character is promising as a result of the significant variance of the experimental data.Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 32–36, January–February, 1990.     

Structural theory of the strength of reinforced plastics

Conclusions In the present study, we developed structural criteria that make it possible to predict at the component level (polymer binder, fibers) and interface level the long-term strength of laminated reinforced plastics in a plane stress state. The proposed relations make it possible to evaluate the effect of the rheological properties of the components, their volume fractions, and the geometry of the structure of the laminated packet on the long-term strength of reinforced plastics. The relations also permit resolution of the inverse problem: efficiently design the structure of such materials for specific loading conditions.Translated from Mekhanika Kompozitnykh Materialov, No. 5, pp. 833–839, September–October, 1989.     

Free vibrations of plastic structures with consideration of the specific nature of the elastic and damping properties of the material (systems with distributed parameters)

A method is proposed for calculating vibrations of plastic structures with distributed parameters. The frequency dependence of the elastic properties and hysteresis losses of the plastics is taken into account in the calculation. The equation of motion of the system, simplified by a number of transformations and assumptions, is solved asymptotically by the Krylov-Bogolyubov method (Pisarenko method) in the first approximation. Since a rigorous solution with the use of the Krylov-Bogolyubov method proved to be complex, the possibility of taking into account the specific nature of the elastic and damping properties of plastics in such problems by other methods is investigated in this work.Mekhanika Polimerov, Vol. 1, No. 4, pp. 136–145, 1965     

Tensile strength of acrylic plastics (PPM) in the presence of a temperature gradient over the thickness of the material

Experimental values of the strength and deformation are presented for SO-95, SO-120, and SO-140 acrylic plastics (polymethyl methacrylate: plasticized, unplasticized, and copolymer) stressed in unaxial tension at v=10 mm/min, stationary temperature gradients of from 2.5 to 17.5 deg/mm over the thickness of the material, and a constant cold-face temperature of 25°C. The deformation properties under these conditions are described: in the presence of a temperature gradient the ultimate strains are higher than for a uniform temperature field at a temperature equal to the cold-face temperature, and the elongation at break falls as the hot-face temperature rises. The tensile strength of plastics with a temperature drop over the cross section can be approximately calculated from the mechanical characteristics obtained for a uniform temperature field.Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 963–969, November–December, 1969.     

Investigation of the dynamic behavior of optically active polymer materials

In view of the importance of the dynamic behavior of optically active plastics in connection with their use in model studies of the earthquake resistance of hydraulic engineering structures by the photoelastic method, the static and dynamic characteristics of the commonest types of photoelastic plastics are presented using published data and measurements made in the Photoelasticity Laboratory of the Vedeneev All-Union Scientific Research Institute of Hydroengineering, Leningrad.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1117–1124, 1967     

Analysis of the effect of transverse shear strains on the stability of multilayer cylindrical shells under external pressure

The effect of transverse shear strains on the critical pressure is investigated using the results of the solution obtained for the problem of the stability "in the small" of elastic multilayer cylindrical shells of regular structure with alternating light and stiff layers. Attention is drawn to the need to estimate the state of stress of the shells in the critical-load zone with the object of studying the desirability of taking the shear effect into account in the stability calculations. The results obtained can be used in calculating the stability of shells made from resin-based composites (glass-reinforced plastics, graphite-reinforced plastics, etc.). The numerical calculations were carried out using a computer.Translated from Mekhanika Polimerov, No. 6, pp. 1066–1070, November–December, 1973.     

On the causes of strength differences in molded plastics filled with mineral powder fillers

It has been established by investigating the effect of common mineral powder fillers on the rate and depth of resin cure that such additions may have an inhibiting or catalytic influence on the hardening process, depending on their nature and method of preparation. The fillers which catalyze the hardening process increase the strength and heat resistance of the cured plastics. When introduced in small amounts into resins used as binders for unsized glass fibers, these fillers equalize the rate and depth of cure in the resin layers, thus increasing the strength and heat stability of glass-reinforced plastics.Mekhanika Polimerov, Vol. 1, No. 5, pp. 58–65, 1965     

Use of plastics in photoelastic stress determination

The use of plastics in photoelastic analysis is described; some special and general requirements relating to plastics used as optically sensitive materials for model-making are formulated. The theoretical premises for obtaining large blocks of epoxy-based optically sensitive material with given opticomechanical properties are developed.Mekhanika Polimerov, Vol. 3, No. 2, pp. 348–356, 1967Paper read at a seminar on polymer mechanics at the Institute of Mechanics, Moscow State University.     

Glass-reinforced plastics based on matrices combining thermoplastics and thermosetting plastics

The conditions of fabrication and the physicomechanical properties of glass-reinforced plastics based on polysulfone combined in different ratios with epoxy resin and Rolivsan were investigated. It was found that realization of the strength of the fibers in glass-reinforced plastics based on three types of binders and mixtures of them at room temperature is approximately the same. The lower strength of glass-reinforced plastics based on polysulfone is determined by the lower concentration of fibers. Modification of thermosetting plastics with polysulfone significantly increases (by 5–8 times) the specific energy of delamination of the glass-reinforced plastics G_1c, which should be manifested by an increase in their crack resistance and other operating characteristics. Modification of ED-20 with polysulfone and polysulfone with Rolivsan significantly increases the glass transition temperature of the polymer and affects the character of the temperature curves of the strength of the glass-reinforced plastics.Institute of Chemical Physics, Russian Academy of Sciences, Moscow. D. I. Mendeleev Russian Chemical Technological University, Moscow. Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 111–117, January–February, 1996.