Influence of structure on the mechanical properties of block copolymers

The variation of the strength characteristics of three-block butadiene-styrene copolymers with the characteristic viscosity has been investigated for polymers of fixed styrene content, as has its variation with the styrene and butadiene content. Measurements were made in the temperature range 20–60°C, at rates of elongation of 5, 50, 250, 500, and 1000 mm/min. It was shown that the relationship between the breaking strength of the block-copolymers and the rate of elongation is analogous to that found for rubber vulcanizates, but has specific features determined by their structure. Values are tabulated for the parameters A and n in the equation giving the relationship between the strength and the rate of elongation under isothermal conditions.     

Effect of structure on the mechanical properties of block copolymers

Experimental data are given on the transitions in three block types in styrene-butadiene copolymers; these transitions were obtained by the dynamic-mechanical method on a torsional pendulum in the –180° to +170° temperature range. Based on these data, kinetic aspects have been advanced on the nature of the transitions based on the formation and decomposition of supramolecular structures of varying type and dimensions.Voronezh Technological Institute. Translated from Mekhanika Polimerov, No. 5, pp. 774–779, September–October, 1972.     

Influence of fiber structure modification on the mechanical properties of flax fiber-epoxy composites

The mechanical characteristics of flax fibers were optimized by using the NaOH treatment process to improve the properties of composite materials. Shrinkage of the fibers during this treatment had a significant effect on the structure and, as a result, on the mechanical properties of the fibers and the composites based on them. Due to the higher mechanical strength and stiffness of flax fibers after NaOH treatment under isometric conditions, the strength and stiffness of composites in general increase. Further, NaOH treatment leads to a rougher surface morphology, as shown, e.g., for jute fibers, compared with the surface of untreated fibers without improved fiber/matrix adhesion.     

Effect of hydrogen-bond network on the thermomechanical and relaxation properties of block copolymers

The thermomechanical and relaxation properties of methyl methaacrylate-methacrylic acid block copolymers have been investigated to study the effect of the controlled hydrogen-bond network due to the presence of carboxyl groups on the mechanical behavior of these copolymers. It has been established that the hydrogen-bond network exerts an influence even at temperatures above the glass transition point, slowing the rate of development of deformation under certain conditions in tests performed in the thermodeformation heating regime, affecting the height and location of the temperature maxima in isometric heating experiments, and reducing the initial compliance and the intensity of the relaxation process at constant temperature and load.Mekhanika Polimerov, Vol. 3, No. 3, pp. 399–403, 1967     

Effect of cellular structure on the mechanical properties of plastic foams

A generalized equation for the compressive stress-strain diagrams of plastic foams is derived on the basis of a 14-faced model of the cell. The results obtained make it possible to predict the polymer base and type of cellular structure required to obtain a foam with predetermined mechanical properties in compression. The calculated values are shown to be in satisfactory agreement with the experimental data.Vladimir Scientific-Research Institute of Synthetic Resins. Translated from Mekhanika Polimerov, No. 4, pp. 594–602, July–August, 1970.     

Relation between the microstructure of block amorphous polymers and certain mechanical properties of the specimens

The structures of PMMA, PS, and PC are considered in relation to the mechanical properties. The part played by the individual elements of the microstructure and their influence on the mechanical strength and deformability of the material are determined. The experimental data obtained by various authors are interpreted on the basis of the microstructural characteristics of polymers.Institute of Problems of Mechanics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 416–421, May–June, 1972.     

Special features of the effect of cellular structure on the mechanical properties of foamed plastics

On the basis of the cell model proposed the mechanical characteristics of high-density foamed plastics are calculated. Assuming the general application of the foaming mechanism and the formation of macrostructure, the principle of structural-mechanical superposition of foamed plastics is established. This enables the equivalence of changes in their strength and elastic properties to be indicated over a wide range of variation of the stiffness of the polymer base and the apparent density of the foamed material.Scientific-Research Institute for Synthetic Resins, Vladimirsk. Translated from Mekhanika Polimerov, No. 6, pp. 976–981, November–December, 1972.     

Effect of modification on the structure and and mechanical properties of chlorosulfonated polyethylene films

Structure formation in chlorosulfonated polyethylene films is described. Modification with phenol-formaldehyde resin leads to a change in the supermolecular structures, which are stabilized by introducing 1% aluminum diisobutoxymonoacetoacetate into the system. It is shown that modifying the chlorosulfonated polyethylene leads to the formation of stable supermolecular structures and a considerable improvement in the mechanical properties of the films.State Scientific-Research and Planning Institute of the Paint and Varnish Industry, Moscow. Karpov Scientific-Research Physico-Chemical Institute. Riga Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 387–390, May–June, 1969.     

The supramolecular structure of polymers and its effect on their mechanical properties

A study is made of the conditions of formation of various supramolecular structures in polymers and their effect on the mechanical properties. The nonuniformity and instability of the structure, and hence of the mechanical properties, may be controlled by means of artificial crystallization nuclei.Mekhanika polimerov, Vol. 1. No. 1. pp. 5–16, 1965The research was carried out at the L. Ya. Karpov Physicochemical Research Institute.     

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.     

Relationship between the molecular structure and certain mechanical properties of oriented polymers

The correlations between the molecular structure and intermolecular energy and the fatigue and elastic properties of fibers are considered. It is shown that the maximum of these properties corresponds to an optimal value of the intermolecular energy.Leningrad Branch of the All-Union Scientific-Research Institute of Synthetic Fibers. Translated from Mekhanika Polimerov, No. 4, pp. 734–735, July–August, 1969.     

Influence of properties of maximal subgroups on the structure of a finite group

We establish some tests for the solvability of finite groups and describe one class of unsolvable groups. We prove that an unsolvable group G such that a maximal subgroup M= P × H is nilpotent and the 2-Sylow subgroup P of M is metacyclic has a normal series GD-g₀TD-{1} such that T is contained in M, G₀/T - PSL (2, q), where q is a power of a prime of the form 2ⁿ± 1 and the index of g₀ in G is not greater than 2.Translated from Matematicheskie Zametki, Vol. 11, No. 2, pp. 183–190, February, 1972.The author warmly thanks V. A. Vedernikov for his guidance and assistance in completing this work.     

Control of the mechanical properties of polymers by modification of their supramolecular structure

Modern ideas on the main types of supramolecular structure in polymers and their various characteristics are discussed, and the possibility of controlling these formations by introducing small amounts of finely dispersed solids is considered. It is noted that crystalline polymers containing artificial nuclei are more resistant to the action of heat and various mechanical influences.Mekhanika Polimerov, Vol. 2, No. 5, pp. 643–650, 1966Presented at the First Conference on Polymer Mechanics (Riga, November 1965).