Change in the properties of impact polystyrene during multiple processing

It has been shown experimentally that the multiple extrusion of grade UP-1E impact polystyrene (5–7 cycles) has almost no effect on most of the physicomechanical properties, the content of volatiles and helium or the residual monomer content. Multiple processing of the same polystyrene by injection molding (10 cycles) causes partial degradation of the material and the destruction of its crosslinked fraction, which results in increased fluidity, reduced molecular weight, and a partial improvement in mechanical properties (approximately up to the fifth or sixth cycle).Mekhanika Polimerov, Vol. 3, No. 1, pp. 156–160, 1967     

Development of forced high-elastic deformations in polystyrene and its self-unloading capacity

The thermodynamic states of two systems of impact polystyrene based on polybutadiene-styrene rubbers are investigated, without introducing spectrography, in terms of the theory of linear viscoelasticity. The results are confirmed by the considerable difference in physicomechanical properties.Ukrainian Scientific-Research Institute of Plastics, Donetsk. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 595–597, July–August, 1968.     

Effect of the molecular weight of polystyrene on the viscosity of concentrated solutions

The viscosity of solutions of polystyrene of various molecular weights (from 1.04 · 10² to 3.8 · 10⁵) in a poor solvent (decalin) and a good solvent (ethylbenzene) has been measured at temperatures from 15 to 70°C over a broad range of shear stresses from 10² to 10⁶ dyne/cm². The nature of the solvent has a considerable influence on the critical molecular weight and the absolute value of the viscosities of the solutions over the entire range of molecular weights and on the form of the flow curves of decalin solutions of polystyrene as a function of temperature. The heat of activation of viscous flow increases with increase in molecular weight and shear stress on the interval 20–80°C. The results obtained are explained in terms of the effect of the molecular weight of the polymer, the nature of the solvent, stress and temperature on structure formation in the solution and on the orientation of the macromolecules and structures in the flow process.Ural Gor'kii State University, Sverdlovsk. Translated from Mekhanika Polimerov, No. 5, pp. 920–926, September–October, 1970.     

Effect of electrical discharges on the mechanical strength and molecular weight of polystyrene film

Electrically aged polystyrene film was examined to determine the effect of voltage, aging time, and nature of the medium on the mechanical strength and molecular weight. It was established that the changes in the mechanical strength and molecular weight of the film always correspond.Mekhanika Polimerov, Vol. 4, No. 1, pp. 59–63, 1968     

Effect of fibrous filler on the mechanical properties of polystyrene and polymethyl methacrylate in the glassy state

The authors have investigated the effect of introducing fiberglas into polystyrene and polymethyl methacrylate films on the transition temperatures and on the intervening glassy-state temperature intervals within which the polymers possess different physicomechanical properties. The variation in a number of the mechanical characteristics of these polymers has been studied as a function of filler concentration within all the subregions of the glassy state bounded by the transition temperatures obtained. Temperature inversion of the reinforcing action of the fibrous filler within the glassy state has been detected. Attention is drawn to the existence at a given temperature of a large number of filled polymer systems with the same reinforcing effect and the same strength at different contents of the same filler in the same polymer.Mekhanika Polimerov, Vol. 3, No. 3, pp. 517–523, 1967     

Molecular orientation and the tensile strength of polystyrene

The tensile strengths of uniaxially oriented polystyrene films with molecular orientation determined by IR spectroscopy are compared. Two different orientation methods involving different time and temperature regimes are employed. It is found that the tensile strength is a unique function of the degree of orientation of the molecular segments of the polystyrene carbon chain irrespective of the means used to orient the specimens and increases linearly with increase in the degree of molecular orientation of the polymer. The experimental dependence is in satisfactory agreement with the results of a theoretical analysis.A. F. Ioffe Physico Technical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 4, pp. 612–615, July–August, 1969.     

Effect of the substrate on the strength of adhesive-bonded joints

The possibility of the adhesion failure of adhesives is discussed. It is shown that the properties of the adhesive film depend on the physicomechanical characteristics of the substrate as a result of the action of molecular forces.V. I. Lenin All-Union Electrotechnical Institute. Translated from Mekhanika Polimerov, No. 2, pp. 295–300, March–April, 1972.     

Effect of fillers and solvents on the properties of polystyrene coatings

The mechanism of coating formation from solutions of atactic polystyrene in xylene and carbon tetrachloride has been investigated. It has been established that, as the filler content increases, in coatings formed from polystyrene solutions containing an evaporating solvent the growth of the internal stresses and the thermophysical characteristics is characterized by similarity of slope, as distinct from the case of coatings obtained from systems containing a polymerizing solvent. It is shown that the nature of the solvent has an important effect on the character of the interaction at the polymer—filler interface and on the structure and properties of the coatings.Kucherenko Central Scientific-Research Institute of Structural Design. Institute of Physical Chemistry, AS USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1127–1129, November–December, 1968.     

Effect of the nature of the filler surface on the properties of phenol-formaldehyde molding powders

The physicomechanical properties and microstructure of phenolic molding powders containing fillers with different surface energies have been investigated. It has been found that an increase in filler surface energy leads to an increase in the density of the resin around the filler particles and hence to an improvement in the physicomechanical properties of the molding powder. A parallel investigation of a molding powder containing a lubricant shows that adsorption of the lubricant on the filler surface reduces the density of the resin, which is accompanied by a deterioration in the properties of the material.Scientific-Research Institute of Precision Engineering Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 677–681, July–August, 1968.     

Fracture mechanism of amorphous polystyrene

The degradation products of polystyrene film specimens have been recorded and their accumulation kinetics in the presence of uniaxial tensile stresses have been studied at various temperatures. It is shown that the accumulation kinetics satisfy the Arrhenius equation for reactions in a mechanical field. The equation for the rupture life can be written in terms of the corresponding parameters of the mechanical degradation reactions. It is concluded that the rupture life and strength of polystyrene depend on the kinetics of mechanical degradation of the polymer chains.A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 3, pp. 541–544, May–June, 1975.     

Investigation of the adiabatic elasticity of polystyrene in the glass-transition region

Experimental results are presented for the density, absorption coefficient, and speed of ultrasound in a morphous polystyrene at frequencies of 375, 910, and 2350 kHz on the temperature interval 15–140°C. The glass-transition temperature does not depend on frequency. The adiabatic elasticity and characteristic impedance are calculated.Kolomna Branch of the All-Union Correspondence Polytechnic Institute. Translated from Mekhanika Polimerov, No. 4, pp. 746–749, July–August, 1973.     

Photoelastic investigation of the flow instability of a polystyrene melt

The flow instability of a polystyrene melt in plane convergent channels is investigated by the photoelastic technique. The possible mechanisms leading to loss of stability are analyzed.Institute of Physics, Academy of Sciences of the Belorussian SSR, Minsk. Translated from Mekhanika Polimerov, No. 3, pp. 564–565, May–June, 1969.     

Properties of reinforced polystyrene in short-time tension,compression, and bending

The mechanical properties of reinforced polystyrene in short-time tension, compression, and bending have been experimentally investigated. Specimens of nine different reinforced-polystyrene compositions with reinforcement ratios of 18.7, 12, and 6.75% and wire diameters of 2, 1, and 0.5 mm were tested. The reinforcement consisted of steel or brass wire. The method of preparing the laboratory specimens is described. The principal results of machine tests on reinforced- and unreinforced-polystyrene specimens are presented. It is shown that certain reinforced-polystyrene compositions possess the properties of a Cosserat medium.Kharkov Structural Engineering Institute. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1059–1064, November–December, 1968.     

Influence of acetone-soluble fraction content on physicomechanical properties of cellulose triacetate

The influence of a change in the acetone-soluble fraction content on the physicomechanical properties of irradiated triacetate (CTA) fibers has been investigated. The results obtained showed that irradiation of CTA sharply alters the acetone-soluble content of CTA fibers, which correlates well with the changes in physicomechanical propertiesKaunas Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 537–539, May–June, 1970.     

Some special features of the structural changes of epoxy resins under the action of magnetic fields

Conclusions 1. The action of a magnetic field leads to a change in the structure of an epoxy resin both at the molecular and at the supramolecular levels.2. A homogeneous magnetic field acting on the hardening process of an epoxy resin, due to the presence of the orientating moment, is able to produce ordered formations.3. A nonhomogeneous magnetic field results in a distribution of anisotropic morphological formations along the field gradient, promoting a change in the physicomechanical properties of the material.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 583–587, July–August, 1978.     

Properties of PS-B polystyrene foam in pure tension and compression

The results of testing polystyrene foam of five different densities in pure tension and compression are presented.All-Union Scientific-Research Institute of Physicotechnical and Radio-Engineering Measurements, Moscow Region. Translated from Mekhanika Polimerov, No. 5, pp. 808–812, September–October, 1971.     

A study of the lifetime of impact-resistant polystyrene as a function of the action of external factors

The effect of temperature, oils, and domestic washing agents on the lifetime of type 475-K high-impact polystyrene has been studied. An intermittent character of the temperature-time dependence of strength has been observed. It has been discovered that household fats and cleaning media significantly affect the strength characteristics of high-impact polystyrene; the greatest action is exterted by the simultaneous action of an oily medium, temperature, and stress.V. I. Lenin Tadzhik State University, Dushanbe. Translated from Mekhanika Polimerov, No. 6, pp. 1121–1123, November–December, 1972.     

Some aspects of the behavior of shock-compressed polymers

The changes in the properties of certain polymeric materials subjected to the action of plane shocks of varying amplitude are discussed. Three loading techniques are employed — single, multiple, and high-frequency multiple loading — each accompanied by a different rise in the temperature of the polymeric material. The results show that the change in physicomechanical properties also varies with the loading technique.Volgograd Polytechnic Institute. Translated from Mekhanika Polimerov, No. 1, pp. 76–80, January–February, 1970.     

Scanning electron microscope study of the structure of carbonized polyacrylonitrile fibers

The morphology and physicomechanical properties of carbonized PAN fibers (oxidized and heat-treated to 1500, 2000, and 2750°C) have been studied. It is shown that surface and internal structural defects sharply reduce the values of the physicomechanical characteristics of the carbonized fibers. The scanning electron microscope reveals the nonuniformities of the fiber over the fracture surface and makes it possible to take into account the effect of macro- and microdefects in studying fiber strength.Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Institute of Fossil Fuels, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1122–1124, November–December, 1971.     

Modification of glass-filled polyamide 66 by reactive oligoorganosilane

Properties of glass-filled polyamide 66 modified by reactive oligoorganosilane were investigated. It was found that modification led to the improvement of the rheological properties of polyamide. The addition of the modifier decreased the glass transition temperature T_g of the polyamide from 60 to 50–59°C, without affecting the melting point. Composites modified by oligoorganosilane are characterized by higher (10–40°C) temperatures of onset and 50% weight loss as compared to the initial composite. It was found that chemical reaction of oligoorganosilane with polyamide and glass fibers took place during coextrusion of the modifier and polyamide, which formed firm chemical bonds between the polyamide and filler and thus favored a considerable improvement in the physicomechanical properties of the composite. The change in the structure and properties of the polyamide observed during modification by oligoorganosilane significantly affected its behavior during friction. The modification made it possible to increase the wear resistance of the composite 1.5 to 2 times and to decrease its friction coefficient from 0.38 to 0.27–0.33. It was also found that the ability of oligoorganosilane to react during its processing with water in the polyamide allowed for a significant decrease in the intensity of hydrolytic processes in the polymer. Because of this, the physicomechanical, rheological, and antifrictional properties of modified composites with an increased content of moisture (up to 3%) in the initial polyamide surpass similar characteristics of the composites containing no modifier, with not only enhanced but also optimum (0.2%) humidity of polymer granules.Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 4, pp. 545–553, July–August, 1998.