Effect of surface treatment of carbon fibers on the strength properties of carbon fiber plastics

Conclusions The strength characteristics of composites based on carbon fibers having a coating of silicon carbide are in direct dependence on the coating thickness and on the porosity, which makes it possible to assume the possibility of increasing the degree of realization of the strength characteristics of fibers having a coating in a composite by increasing the degree of impregnation of the carbon cord with the binder. The latter finds confirmation also in the fact that at a small coating thickness on the carbon fiber (of the order of 5 nm) the porosity of the composite obtained is equal to the porosity of the material based on the carbon fiber without coating. Moreover, as is evident from Fig. 3c, the casing of silicon carbide does not form a continuous coatting over the whole perimeter of the cord. The presence of these prerequisites, and also the high resistance of carbon fibers having a silicon carbide coating to oxidation [9], open up wide prospects for creating new composite materials based on them.Translated from Mekhanika Kompozitnykh Materialov, No. 4, pp. 603–606, July–August, 1979.     

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     

Effect of extended storage on the mechanical properties of reinforced plastics

The effect of storage time (6–10 years) on the mechanical properties of KAST-V glass laminate, textolite, and SVAM glass-reinforced plastic has been experimentally investigated.Moscow Lomonosov State University. Translated from Mekhanika Polimerov, No. 3, pp. 556–558, May–June, 1969.     

Effect of silane coupling agents on the physicomechanical properties of glass-reinforced plastics

The chemical nature of the coupling agent is investigated in relation to its effect on the wet and dry flexural strength of specimens of polyester glass-reinforced plastic (GRP), the water absorption of the material, and the degree of polymerization of the resin.Mekhanika Polimerov, Vol. 3, No. 5, pp. 787–794, 1967     

Effect of moisture on the viscoelastic properties of an epoxy-clay nanocomposite

The results of a complex study on the viscoelastic behavior of an epoxy-clay nanocomposite after a long-term exposure to moisture are presented. The main laws of variation in the glass-transition temperature of the nanocomposite in relation to the different content of filler and absorbed moisture were determined by using a thermomechanical analysis. The loading levels in creep experiments were chosen according to the results of quasi-static tensile tests. The sets of creep and creep recovery curves obtained were approximated by the Boltzmann–Volterra linear integral equation with account of the principle of moisture-time analogy. The variation in the spectrum of retardation time of the epoxy resin with introduction of the nanofiller was estimated. It is shown that the moisture-time reduction function correlates with changes in the forced rubber-like elasticity and the volume of nanocomposite specimens upon their moistening.     

Effect of fiber curvature on the modulus of elasticity for unidirectional glass-reinforced plastics in tension

The effect of curvature of the fibers on the modulus of elasticity of unidirectional glass-reinforced plastics (GRP) in tension has been investigated on the basis of the theory of layered reinforced media with random initial irregularities [1,2]. It is shown experimentally that relatively minor distortion of the fibers during manufacture may result in important changes in the modulus of elasticity. A model is proposed for determining the effect of fiber curvature on Young's modulus; experiments on specimens with a given regular fiber curvature indicate good agreement with the theory. The effect of prestressing the fibers on the modulus of elasticity has been studied using commercial AG-4S material and the optimum prestress has been established.Mekhanika Polimerov, Vol. 3, No. 2, pp. 243–249, 1967     

Effect of temperature on the mechanical characteristics of carbon plastics reinforced with metal mesh

The behavior of carbon plastics based on FN resin and FN plus rubber and reinforced with metal mesh is investigated over a broad range of temperatures in tension, compression, and pure bending. The presence of a rubbery component considerably reduces the strength of the plastic while improving its deformation properties.Dnepropetrovsk State University. Translated from Mekhanika Polimerov, No. 2, pp. 358–361, March–April, 1971.     

Main features of the viscoelastic behavior of carbon fiber-reinforced plastics with a polymer matrix: Model study and calculation

It was shown that below the glass transition temperature of the amorphous matrix, its viscoelastic behavior in a composite is described by the Halpin-Tsao equation for composites, as modified by Nielsen, with a sufficient degree of reliability. However, when the matrix passes into the highly elastic and especially the viscous flow state characteristics of thermoplastic matrices, a significant difference is observed in the experimental and calculated temperature curves of the elastic and matrix loss moduli. It is possible to hypothesize that this is due to hindrance of plastic deformation of the matrix in the composite not accounted for in the Halpin-Tsao model. Using simple models of the one-sided coating and sandwich type, it was shown that consideration of the stress state of a matrix in contact with a rigid coating can result in the same kind of effects as in a composite, namely, apparent toughening of the matrix in the highly elastic region and shifting of the maximum of the mechanical loss modulus to the high-temperature region.Institute of Macromolecular Compounds. Russian Academy of Sciences, St. Petersburg, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 5, 690–703, September–October, 1997.     

Effect of surface modification on the adhesion and mechanical properties of glass-reinforced plastics

The adhesion of an epoxy-polyester resin to glass fibers with clean and modified surfaces has been determined. The effect of this adhesion on some of the properties of glass-reinforced plastics (bending, tension, shear) is investigated.Mekhanika polimerov, Vol. 1, No. 1, pp. 93–99, 1965     

Effect of certain technical and geometric factors on the properties of glass-reinforced plastics

Experimental data are used as the basis for a discussion of some of the technical factors affecting the strength of filament-wound glass-reinforced plastics (GRP): winding speed, tension on the glass, life of resin. A relationship between the strength of GRP and these factors is demonstrated. The effect of the thickness and diameter of the test piece on the tensile strength of GRP material is examined.Mekhanika Polimerov, Vol. 3, No. 1, pp. 99–103, 1967     

Effect of curvature of the fibers on the elastic properties of unidirectionally reinforced plastics

An approximate method is proposed for determining the reduced elastic constants of reinforced plastics (glass-reinforced plastics) with allowance for the curvature of the reinforcing fibers. All the conclusions relate to plane stress. The results of model tests are presented as confirmation of the theoretical conclusions.Mekhanika Polimerov, Vol. 3, No. 5, pp. 858–863, 1967     

Study of the effect of the dressing of carbon fibers on the properties of carbon-fiber-reinforced plastics based on polyacetals

Studies are made of the mechanical and friction engineering properties of a copolymer of trioxane-1,3,5 with dioxolan-1,3 reinforced with dressed carbon fibers based on hydrated cellulose. Polyalkyloxysilanes are used as the finishes. The optimum concentrations of the finishes on the fibrous filler are determined. Relations are obtained to describe the dependence of the mechanical properties of carbon-fiber-reinforced plastics on the type of finish and its effect on the condition of the phase boundary between filler and the polymer matrix. The effect of adhesion of the polymer to the fibrous filler on the properties of a randomly reinforced thermoplastic composite is also determined. The dependences of the friction engineering properties of polyacetal-based carbon-plastics on the loading parameters of the friction-loading unit are examined. The material that is developed has high values of strength, elastic modulus, and notch toughness and low values of the friction coefficient and shrinkage. The material can be used as structural and anti-friction elements in rocketry, aviation, and the automobile industry.Ukrainian State Chemical Engineering University, Dnepropetrovsk. Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 90–97, January–February, 1997.