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.     

Mechanical characteristics of oriented glass-reinforced plastics in shear

The mechanical characteristics of oriented glass-reinforced plastics stressed in shear are considered. Various methods of determining them are compared. The dispersion of the shear strength is characterized and the possibility of glass-reinforced plastics elements failing as a result of low interlaminar shear strength is discussed.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1008–1013, November–December, 1969.     

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.     

Physicomechanical properties of radiation-cured PN-1 polyglycol maleate resin

The radiation and thermochemical methods of crosslinking polyesters are compared with reference to PN-1 resin, commonly used for glass-reinforced plastics. Certain physicomechanical properties of copolymers obtained by the two methods are examined. It is established that the radiation copolymers have greater rigidity and strength.Mekhanika Polimerov, Vol. 3, No. 3, pp. 395–398, 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.     

Resistance of glass-reinforced plastics to long-term shear failure

The time dependencies of the strength of glass-reinforced plastics in shear under steady, continuous and alternating loads are examined. Failure under steady and continuous loading is depicted by means of an exponential model of the build-up of damage.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, No. 2, pp. 295–302, March–April, 1970.     

A rheological model of polymers and glass-reinforced plastics

Network polymers and the corresponding glass-reinforced plastics are investigated for a homogeneous uniaxial state of stress and constant temperature. A physical law relating the high-elastic strain and the stress in explicit form with once-determined structural constants is obtained for the damped (bounded) creep regime. The theoretical solutions are compared with the experimental data for a glass-reinforced plastic based on unsaturated polyester resin and glass mat reinforcement.Institute of Engineering Mechanics, Bulgarian Academy of Sciences, Sofia. Translated from Mekhanika Polimerov, No. 5, pp. 851–857, September–October, 1971.     

Investigation of the adhesion strength of carbamide resins

The adhesion of carbamide resin to clean or treated fiber glass surfaces has been determined. The effect of this adhesion on the strength of glass-reinforced plastics is examined.Moscow Mendeleev Chemical Engineering Institute. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1119–1121, November–December, 1968.     

Estimation of the anisotropy of the short-time and long-time strengths of glass-reinforced plastics

A linear correlation between the tensile stress and the logarithm of the lifetime of a glass-reinforced plastic in various directions in the plane of the sheet has been experimentally established. The parametric introduction of the time factor into the criterion of the short-time strength of anisotropic materials is proposed as a first approximation. The Gol'denblat-Kopnov criterion is used to derive a simple relation describing the strength properties of glass-reinforced plastics in the uniaxial state of stress.Moscow Institute of Chemical Machine-Building. Scientific-Research Institute of Mechanics, Moscow Lomonosov State University. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 243–249, March–April, 1969.     

Predicting certain structural characteristics and physicomechanical properties of glass-reinforced plastics from their thermal activity

A procedure and apparatus for determining the thermal activity of glass-reinforced plastics with one-sided access have been developed. A correlation is established between the interlaminar shear modulus and interlaminar shear strength and the thermal activity of a glass laminate. The effect of structural inhomogeneities and bonding flaws on the thermal activity of a glass-reinforced plastic is investigated and it is shown that the location of an inhomogeneity within the article can be determined.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 128–132, January–February, 1976.     

Determination of the magnitude and distribution of the initial stresses in glass-reinforced plastics

The stresses that develop in the resin at and near the glass-resin interface during the curing of polyester and epoxy glass-reinforced plastics have been experimentally studied by the photoelastic method. The volume state of stress in three mutually perpendicular directions in various sections and in the danger zones is qualitatively and quantiatively described. It is established that the stresses investigated may be the cause of cracking that reduces the tightness and strength of the glass-reinforced plastic.I. M. Gubkin Moscow Institute of the Petrochemical and Gas Industry. Translated from Mekhanika Polimerov, No. 4, pp. 661–667, July–August, 1973.     

Resistance of wound glass-reinforced plastics to failure by unwinding

The debonding of wound glass-reinforced plastics is examined from the statistical standpoint. The statistical stress intensity distribution function characterizing the fracture toughness is obtained. The effect of defect size on the critical nominal stresses is discussed.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, No. 5, pp. 881–885, September–October, 1969.     

Effect of fiber tension on the unwinding resistance of hardening layers of glass-reinforced plastic

The shear fracture toughness characteristics of glass-reinforced plastics used for strengthening metal pressure vessels have been determined by testing metal-GRP rings. The shear fracture toughness characteristics are statistically estimated for a unidirectional GRP as a function of the winding tension.K. É. Tsiolkovskii Moscow Aviation Engineering Institute. Translated from Mekhanika Polimerov, No. 5, pp. 935–938, September–October, 1975.     

Stresses in various resins cured on glass films

By using Sanzharovskii's method for determining the stresses in lacquer coatings and employing as a model a layer of resin deposited on a glass film, it is possible to simulate the processes that take place in glass-reinforced plastics and determine the stresses that develop in different resins cured under various conditions. The method proposed makes it possible to estimate the effect on the stresses of the shrinkage of the resin, its elasticity, and the difference in the coefficients of thermal expansion of the resin and the glass. Such an investigation is desirable before selecting the composition of the resin, additional organic or mineral fillers and elasticizers, and the optimal curing regime for glass-reinforced plastics.All-Union Scientific-Research Institute of Aviation Materials, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 481–486, May–June, 1969.     

Correlation between the strength and thermal conductivity of glass-reinforced plastics

The effect of changes in the component ratio and porosity of glass-reinforced plastics on their strength and thermal conductivity is considered. A correlation is shown to exist between the bending strength and thermal conductivity of a glass laminate.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 749–751, July–August, 1969.     

Residual stresses in glass-reinforced plastics parts

The determination of the residual stresses in glass-reinforced plastics elements is considered. It is shown that these stresses reach appreciable values and should be taken into account in strength calculations. Quantitative data are supplied for a series of materials. At normal operating temperatures the residual stresses are stable.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1117–1119, November–December, 1969.     

Effect of proton-electron irradiation on the strength of a glass-reinforced plastic and its components

The action of protons and electrons on the properties of glass strands under vacuum conditions has been experimentally investigated. The experimental procedure is described. The effects of irradiation, strain rate, and reduced temperature and pressure on the properties of glass reinforcement and glass-reinforced plastics are estimated.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev; Physicotechnical Institute of Low Temperatures, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 4, pp. 755–760, July–August, 1970.     

Oxygen etching of polyamides

The application of oxygen etching to polymers of the polyamide series, including KS-30/9 and SP-68 glass-reinforced plastics, has been investigated. The results obtained point to the possibility of using this method for studying the structure of polyamides.Voroshilovgrad Machine-Building Institute. Translated from Mekhanika Polimerov, No. 6, p. 1096, November–December, 1971.     

Calculation of the moduli of elasticity and tensile strength of oriented glass-reinforced plastics on the basis of a nondestructive determination of their composition and structural parameters

The theoretical basis of the nondestructive determination of the modulus of elasticity and tensile strength of oriented glass-reinforced plastics in the direction of the principal axes of anisotropy from the resin content and porosity of the finished product is examined. The results of an experimental verification are presented.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 332–341, March–April, 1969.     

Propagation of elastic waves along the fibers in oriented glass-reinforced plastics

The dispersion equation is derived for axisymmetric (longitudinal and torsional) normal vibrations in oriented glass-reinforced plastics. The low-frequency case is examined in detail. The frequency limits of applicability of the method of substituting a homogeneous medium for the composite (GRP) are estimated. The dependence of the vibration propagation velocity on glass content is calculated.Leningrad Zonal Scientific-Research Institute of Experimental Design of Public and Residential Buildings. Translated from Mekhanika Polimerov, No. 6, pp. 976–983, November–December, 1973.