V.Ye. Gul

Cryolysis and its effect on rigid chain polymer structure

Abstract Freezing the aqueous solutions of rigid chain polymers will result in the development of complicated cryolytic processes, such as decomposition and structuration, which will produce structural changes. Polyvinyl alcohol (PVAL) is used as the example to show the results of the structural parameter determinations of the network which was produced by cryolysis.

Correlation by physical and chemical methods of the transverse crosslinking density in unsaturated polyester copolymers

The following relationship correlated equilibrium stress with deformation according to the statistical theory of high elasticity [1, 2]: σ∞ = 2C (λ −1/λ2) in which σ∞- equilibrium stress, kg/cm2, λ-deformation; λ = l/l0, C-elasticity constant, kg/cm2, C-NkT/2 (N-number of chains per unit volume, k-Boltzmann constant, T-abs. temperature, °K). The statistical theory equation can be regarded as a special case of the phenomenological Mooney-Rivlin equation, which establishes the relation between equilibrium stress and deformation in the range of small and medium deformation due to uni-axial elongation [3–5]: σ∞ = 2C1 (λ−1/λ2) + 2C2·1λ (λ−1λ2) in which C1, C2 are constants, and C1 has the same meaning as the C of eqn. (1).

Effect of the structure of electrically conducting polymer compositions on their properties. Review

Abstract This literature survey covers research on the properties of systems consisting of a polymeric binder and an electrically conducting filler. The conditions are discussed, under which structure is developed in these compositions, in which the specific volume resistance is reduced suddenly by several orders of magnitude and the system becomes capable of carrying an electric current. Theoretical considerations and experimental evidence relating to possible mechanisms of conduction in these systems are discussed.

Study of relaxation properties of several heat resistant polymers

Using P-2 polyarylate, aromatic polyamide of phenylon (S-4), polyamidoimide and polyoxadiazole a study was made of the effect of the chemical structure of heat resistant polymers on relaxation properties determining the mechanical efficiency of these systems over a wide range of temperature, stress and deformation. A detailed analysis of relaxation behaviour of the systems studied indicates that they have a wide temperature range, in which parameters of relaxation processes are of low sensitivity to temperature. It was also found that heat resistant polymers which have sustained much higher prolonged stress, compared with traditional plastics, should be given preference not only in the range of high temperature, but also in the range of low temperature.

Effect of a carbon black-graphite filler on the thermal degradation of a methylphenylsiloxane polymer☆

Abstract GLC methods have been used in the study of the composition of the products of thermal degradation of crosslinked polymethylphenylsiloxane containing disperse carbon black-graphite fillers within tho polymer matrix. In presence of these fillers shift in the temperature of the onset of intense decomposition of the polymer towards higher temperatures is observed with an increased contribution of the secondary reactions and also a substantial fall in the yield of the products of thermal degradation. This is due to decrease in the mobility of the polymer chains in the filled crosslinked polymeric system as a result of their orientation on the surface of the carbon black-graphite filler, slowing of the diffusion of the primary products of the degradation conversions and also possible inactivation of the silanol groups of the polymer on the filler surface.

The mechanism of adhesion in the contact zone between a metal and a polymer melt

Abstract Two types of defects participate in increasing the true contact surface between an aluminium foil polyethylene melt, namely the defects and the pores in the oxide film which is always present on the aluminium foil surface; the extent of participation depends on the melt temperature. A method of calculating the true contact surface between the aluminium foil and the polyethylene melt is suggested.

The effect of the relaxation properties of a twin layer film material on its mechanical uses

Abstract The system Lavsan-PE has been used to investigate the effects of the relaxation properties of a twin layer film material on its mechanical use. The parameters of the Kohlrausch equation have been determined and used to analyse the usefulness (working capacity) of the system.

On the optical-mechanical properties of laminated film materials☆

Abstract It is shown that the strength properties of laminated film materials are determined by the orientational ability of the adhesives, which in turn depends on the structure and adhesion of the latter, while structural changes in the adhesives compared with the initial structures occur both during the preparation of laminated materials and as a result of test methods.

Investigation of the effect of oxygen on the reaction between polypropylene and lignin

Abstract The effect of oxygen on the interaction between polypropylene and lignin radicals formed in the processing of poprolin has been investigated. It has been shown that the formation of lignin free radicals is increased to a considerable extent by atmospheric oxygen present in the system, and the interaction of the lignin free radicals with polypropylene is almost completely absent under vacuum conditions. It has been established on the basis of X-ray structural analysis that the introduction of lignin into the polypropylene melt is not accompanied by any change in the degree of crystallization, in the morphology of the crystalline structure or in the crystal-lattice parameters and the observed changes in the properties of the system may therefore be attributed to the occurrence of chemical free radical processes.

Electrically conducting systems based on polymers—II. Investigations of the structure of conductive compositions based on hardened resins☆

In the previous work the basic principles of the formation of conductive systems from uncured resins were dealt with [1]. The present work is concerned with the examination of the hardening process whereby the materials under examination pass gradually from the viscous-flow to the solid state during the period of observation. The authors followed the structural changes occurring during the hardening of compositions based on a phenol-formaldehyde resole resin and the epoxide resin E-40 containing various proportions of acetylene black, and compared the results with the results of the measurement of electrical properties. In experiments on the hardening of the resins the specimens were held for a suitable time at a high temperature—the phenol-formaldehyde compositions at +150° and the epoxide compositions at +80°. In order to study the structural changes occurring during the curing process an apparatus was designed, which in conjunction with a Polyani dynamometr and a PMT-3 micro hardness gauge enabled the variation in viscosity of the polymeric systems during hardening to be followed. The apparatus was a modification of the Volarovich and Tolstoi dynamometer [2] in conjunction with a Polyani dynamometer. By measuring the limiting load P required to stretch rods of the hardened compositions it is possible to determine the absolute shear stress.