New method of determining the brittle point of polymers

A new method is proposed for determining the brittle point of polymers. This method, based on testing specimens with "frozen-in" internal stresses, makes it possible to determine the lower temperature limit of forced segmental mobility of the macromolecules of linear and crosslinked polymers in the solid state.Scientific-Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 554–556, May–June, 1976.     

Thermomechanical method for determining the molecular weights of amorphous linear polymers

A thermomechanical investigation of polyisobutylene specimens under various time and stress conditions enabled us to extend the applicability of this method of determining the molecular weight of an undissolved polymer. The previously proposed mechanical model of a polymer, which is the basis of the relationship between the molecular weight of the polymer and the difference between the yield and glass-transition temperatures, must be refined to make allowance for the supramolecular structure.Mekhanika Polimerov, Vol. 3, No. 4, pp. 586–590, 1967     

Ultrasonic method of determining the elastic characteristics of anisotropic materials

An ultrasonic method of determining the elastic characteristics, developed for isotropic materials and based on the measurement of the angles of total internal reflection of ultrasound at a liquid-solid interface, is applied to an anisotropic Compreg of the DSPA type. The results obtained for the shear modulus using the ultrasonic method at 2.5 MHz and an independent method based on measuring the frequency of the damped torsional vibrations of a prismatic bar at 10–30 Hz are compared. It is shown that the shear modulus varies only slightly (10–12%) on the frequency interval investigated.Leningrad Kirov Forest Engineering Academy. Translated from Mekhanika Polimerov, No. 4, pp. 728–731, July–August, 1969.     

Rapid method of determining temperature dependence of adhesion of polymers to metals

A new method of determining the temperature dependence of the adhesion of polymers to metals and an equipment for carrying this out are described. The adhesion of the polymer to metal is determined by stripping the film from a metal plate or bar with a temperature gradient in the plane of adhesive contact in the direction in which the film is stripped.     

Use of computers to calculate the mechanical characteristics of relaxation processes in polymers

A method of calculating the constants found in Kohlrausch's empirical function describing relaxation processes is proposed, which is based on the application of a well-known algorithm for solving nonlinear problems on a computer using the conjugate gradient method. All the experimental information is used by this method and the degree of calculation accuracy is increased. The reproducibility of calculations to find these constants is found to be satisfactory in the case under investigation when the duration of the experiment is varied.     

Instrument for investigating the dynamic mechanical properties of polymers by the resonance vibration method

The RUIZ-2T instrument for automatically measuring the dynamic modulus of elasticity and decrement of plastics in the resonance vibration regime is described.Rostov-on-Don Institute of Railroad Transport Engineers. V. I. Lenin Moscow State Pedagogical Institute, Problem Laboratory of Polymer Physics. Translated from Mekhanika Polimerov, No. 6, pp. 1100–1101, November–December, 1971.     

Compound vibrator method of determining the complex deformation characteristics of polymeric materials

The propagation velocities c and logarithmic decrements in the longitudinal and shear modes, used for calculating the complex deformation characteristics of polymeric materials, can be simultaneously determined by means of a compound vibrator with a mechanical clamp. Relations are obtained for determining c and when the other end of the specimen is free or fixed and with allowance for the mechanical losses in the measuring rod. The method has been tested on specimens of P-4020E polyethylene at various temperature.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 116–123, January–February, 1970.     

Boundary layer method in the problem of far propagation of surface SV-waves

The SV polarized wave field is investigated in an elastic gradient layer of constant width. A point source is situated on the boundary of the layer. Rigid contact conditions are assumed to be valid on the boundary between the layer and an elastic half-space. It is shown that the interference field in the principal approximation far from the source does not depend on the relation between the phase velocity and the transversal and longitudinal velocities in the half-space. Bibliography: 11 titles.     

Method of determining thermophysical coeffients of polymers

This article presents the solution of the problem of the temperature field of a two-piece cylinder under boundary conditions of the second kind. On the basis of the results of the derived solution a method is developed for investigating the thermophysical coefficients of polymers in relation to temperature and pressure.Mekhanika Polimerov, Vol. 1, No. 6, pp. 132–137, 1965     

An investigation of the dynamical mechanical properties of some block polymers using the resonant vibration method

Some results are presented, obtained on the RUIZ-2T apparatus, for the determination of the decrement and characteristic vibrational frequencies of polymer samples by the resonance method.V. I. Lenin Moscow State Pedagogical Institute, Problem Laboratory for the Physics of Polymers. Rostov-on-Don Institute for Railway Transport Engineers. Translated from Mekhanika Polimerov, No. 1, pp. 152–154, January–February, 1972.     

Dynamic modulus of elasticity and resistance to mechanical breakdown of individual polymers and their mixtures

It is shown that when polystyrene, polymethyl methacrylate, polyvinyl acetate, and an ultramicroheterogeneous mixture of polyvinyl acetate and polymethyl methacrylate are vibroground in the brittle state, the resistance of the system to mechanical breakdown is determined by its elastic properties.Moscow Technological Institute of the Wood Industry. Translated from Mekhanika Polimerov, No. 4, pp. 744–745, July–August, 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.     

Intensity of mechanical action and mechanical degradation of rigid polymers

The authors have investigated the relation between the degradation of rigid carbon-chain polystyrene, polyvinyl acetate, and polymethyl methacrylate polymers with the kinetics of mechanical degradation during vibromilling. They determine the critical value of the intensity necessary for the onset of the degradation process.Moscow Technological Institute of Light Industry. Translated from Mekhanika Polimerov, No. 2, pp. 362–364, March–April, 1974.     

Fourier regularization method of a sideways heat equation for determining surface heat flux

We consider a non-standard inverse heat conduction problem in a quarter plane which appears in some applied subjects. We want to know the surface heat flux in a body from a measured temperature history at a fixed location inside the body. This is an exponentially ill-posed problem in the sense that the solution (if it exists) does not depend continuously on the data. A Fourier regularization method together with order optimal logarithmic stability estimates is given. A numerical example shows that the theoretical results are valid.