Relation between the shear and longitudinal viscosity coefficients for concentrated polymer solutions

A relation between the shear and longitudinal viscosity coefficients is obtained on the basis of the theory of flow of polymeric systems in the single relaxation time approximation. A comparison of the shear and longitudinal viscosity coefficients for polymer melts and solutions shows that the relation obtained is valid over a broad stress region.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Scientific-Research Institute of Synthetic Fibers, Moscow. Translated from Mekhanika Polimerov, No. 1, pp. 124–131, January–February, 1973.     

Variation of the deformation resistance of phenol-formaldehyde thermosets during cure

The dependence of the viscosity of phenol-formaldehyde thermosets on the previous thermal history has been investigated at a fixed shear rate.Moscow Institute of Chemical Machine Building. Institute of Problems of Mechanics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 619–623, July–August, 1971.     

Experimental determination of the influence of periodic shear deformation and filling on the effective viscosity of solutions of synthetic rubber

The influence of periodic shear deformation on the effective viscosity of filled solutions of synthetic rubber has been studied. The study was carried out on an amplitude-frequency viscosimeter developed by the authors. It has been established that during periodic deformation a linear region exists in which the effective viscosity is independent of the vibration rate, and a nonlinear region where the effective viscosity of the solutions decreases with increase in amplitude of the speed of relative deformation.Presented at the IV Symposium on Rheology of Polymers at the A. V. Topchiev Institute for Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow, May 27–30, 1969.Institute for Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, 514–520, May–June, 1970.     

Effect of harmonic shear deformations on the viscosity of epoxy potting compounds

A method has been developed for experimentally determing the effect of harmonic shear deformation on the effective viscosity of pseudoplastic liquids. Harmonic deformation substantially reduces the effective viscosity of a filled composition based on epoxy resin ED-5.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 328–331, March–April, 1969.     

Effect of technological factors on the structure and properties of Eskaplen film material

The effect of the composition of the solvents, the concentration of the solutions, and the rate of film formation on the structure and properties of Eskaplen film material obtained on the basis of SKI-3 isoprene rubber hydrochloride has been investigated. The properties of the film material are shown to depend on the structure that develops during the film-forming process.Moscow Technologic Institute of the Meat and Dairy Industry. Translated from Mekhanika Polimerov, No. 1, pp. 8–13, January–February, 1973.     

The acoustic properties of polymers with an asymmetric potential barrier at liquid-helium temperatures

The pulse-phase compensation method has been used to measure the propagation velocities of longitudinal and shear waves in polyvinyl chloride, polyvinyl fluoride, and polystyrene at frequencies of 1 and 5 MHz on the temperature interval 2.1–240°K. It has been established that as the temperature falls to 2.1°K the speed of ultrasound in these polymers monotonically increases, the dispersion (frequency dependence) of the speed of sound being preserved over the entire temperature interval. Two possible causes of the viscoelastic relaxation observed in the investigated polymers in the region of helium temperatures are considered.Scientific-Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 749–751, July–August, 1973.     

Effect of loading on the roughness set in run-in metal - rubber surfaces

A study has been made on the effect of loading on the roughness set of a metal surface run-in with rubber containing an SKN-18 + SKN-26 nitrile rubber blend in conditions of friction without lubrication. The experimental results are compared with those calculated.State Scientific-Research Institute of Mechanical Engineering, Moscow. Scientific-Research Institute of the Rubber Industry, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 737–740, July–August, 1972.     

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.     

Effect of ultrasonic vibrations on the flow of a viscoelastic liquid

The rheological characteristics of a viscoelastic liquid flow, on which finite-amplitude ultrasonic shear vibrations have been superimposed, are investigated. It is shown that at periodic deformation amplitudes of 5 µ or more there is a thixotropic reduction of the viscosity and elasticity of the system owing to the destruction of certain types of structural bonds. The experimental apparatus is described.Moscow Institute of Chemical Machine Building. Translated from Mekhanika Polimerov, No. 6, pp. 1097–1099, November–December, 1971.     

Periodic deformation and viscous flow of polymer solutions and melts

The transition from the start of deformation to the establishing of a stationary state of nonlinear, periodic shear deformation and the kinetics of the change in the mechanical characteristics after deformation at finite amplitudes has ceased have been investigated. The calculated values have been compared with those obtained experimentally.For Communication 2 see [3].Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Institute of Mechanics Problems, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 521–529, May–June, 1970.     

Dynamic deformation of a stationary rubber flow

The effect of dynamic deformation on the stationary flow of a rubber composition has been experimentally investigated for comparable values of the stationary and dynamic strain rates. The dependence of the effective viscosity on the stationary shear rate is not equivalent to its dependence on the periodic shear rate amplitude. An expression is given for calculating the effective viscosity in the case of combined stationary and dynamic shear deformation. The effectiveness of the dynamic deformation, estimated in terms of the effective viscosity, depends on whether it is superimposed on the stationary flow at constant stationary shear rate or at constant stress. It is proposed to estimate the effectiveness of dynamic deformation of a stationary non-Newtonian flow in terms of the change in the power of the stationary forces. When the effective viscosity is reduced by dynamic deformation of the stationary flow, the power of the stationary forces increases at constant shear stress and falls at constant stationary shear rate.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 489–496, May–June, 1971.     

Mathematical model of polytropic polymer extrusion

The basic equations of the statics of the extrusion process have been derived with allowance for viscosity anomaly, heat-transfer effect, and the dependence of the actual length of the metering zone on the regime parameters. The model obtained makes possible the analytic determination of the output and the temperature and pressure of the melt at the screw outlet. The theoretical results are compared with experiment.All-Union Scientific-Research Institute of Agricultural Machine-Building, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1095–1101, November–December, 1970.     

Periodic deformation and viscous flow of polymer melts and solutions (communication 1)

The principles of the theory of thixotropy are formulated. The basic relations are obtained for cases of periodic vibration superimposed on shear flow. The effect of stationary shear flow on the linear dynamic characteristics of an elastic liquid is investigated. The calculated values are compared with the experimental data.Institute of Problems of Mechanics, Academy of Sciences of the USSR, Moscow. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 519–527, May–June, 1969.     

Periodic deformation and viscous flow of polymer solutions and melts

The effect of nonlinear periodic deformation on the relaxation spectra and viscous-elastic characteristics of polymer melts and solutions is considered. The experimental and calculated relationships between the dynamic characteristics and effective viscosity and the amplitude of the rate of periodic deformation were compared.For Communication 1, see [6].Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Institute of Mechanics Problems, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 2, pp. 357–366, March–April, 1970.     

Periodic shear deformation of a curing epoxy composition

The curing of an epoxy resin with amines is investigated in relation to the changes in the viscoelastic shear characteristics. The effect of the shear deformation amplitude on the curing kinetics is considered.Presented at the Symposium on Polymer Rheology, Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow, May, 1970.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 301–306, March–April, 1971.     

Barus effect in polymer flows through cylindrical and flat dies

The determination of the swell factor of a polymer jet extruded from a cylindrical or flat die is examined. Relations are obtained for the dependence of the swell factor on shear rate and shear stress, expressed in terms of the constants of the rheological model.Scientific Research Institute of Plastics, Moscow. Kiev Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 487–492, May–June, 1976.     

Effect of the nature of the solvent on the mechanical and adhesion properties of atactic polystyrene

The effect of the supermolecular structure on the internal stresses and adhesion of coatings obtained from solutions of atactic polystyrene has been investigated. The structure of the coatings depends on the nature of the solvent and is nonuniform with respect to the morphology, size, distribution, and state of order of the structural elements. The greatest strength and adhesion correspond to fibrillar structures.Kucherenko Central Scientific Research Institute of Building Structures, Moscow; Institute of Physical Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 793–797, September–October, 1969.     

Effect of the type of state of stress on the characteristics of the mechanical glass transition process in polymers

The effect of the type of state of stress on the activation energy and relaxation time is investigated with reference to the mechanical glass transition (softening) process in polymers. An expression relating the mechanical glass transition temperature with the structural glass transition temperature, the mean stress, and the stress intensity is obtained for isotropic homogeneous polymers. Experimental data obtained for polymethyl methacrylate in uniaxial tension and compression, pure bending, and shear are presented.All-Union Scientific Research Institute of Aviation Materials, Moscow. Translated from Mekhanika Polimerov, No. 2, pp. 195–199, March–April, 1971.     

Theory of flow of concentrated polymer solutions and melts

Starting from the concept of a polymer system as a collection of macromolecules forming an effective network, an expression is obtained for the stress tensor of a flowing concentrated polymer solution or melt. It is shown that the variation of the effective viscosity of polymer systems is associated with the orientation of the macromolecules and changes in the equilibrium number of nodes during flow. A system of equations describing the flow of polymer systems characterized by a gradient dependence of the effective viscosity and normal stresses in shear is written in the single relaxation time approximation.Institute of Chemical Physics, Moscow Region, Academy of Sciences of the USSR. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 724–730, July–August, 1968.     

Dynamic properties of certain unvulcanized rubbers in the high-elastic and fluid states

The dynamic properties of a series of unvulcanized rubbers (cis-polybutadienes, Na-polybutadiene, cis-polyisoprene, butyl rubber, polyisobutylene, and ethylene-propylene copolymer) have been investigated in a low-frequency dynamic testing machine and a frequency rheometer on the frequency range from 5 · 10^–2 to 4.5 · 10³ Hz at temperatures of 25 and 60°C. At these temperatures the mechanical loss factor is the most sensitive criterion of transitions from one physical state of the polymer to another. For all the specimens investigated on the experimental range of angular frequencies the modulus of the complex dynamic viscosity and the effective viscosity determined under static conditions coincide, assuming the equivalence of angular frequencies and shear rates.A. V. Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 698–703, July–August, 1969.