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The relaxation properties of chemisorption fibers based on copolymers of acrylonitrile and 2-methyl-5-vinylpyridine synthesized in aqueous medium and in dimethyl sulfoxide were investigated. It was shown that the conditions of synthesis of the copolymers affect the relaxation properties of the fibers. It was hypothesized that the change in the relaxation properties is due to the composite composition of the copolymers, which is determined by the copolymerization constants.

Mesomorphic films have been prepared from isotropic solutions of cellulose diacetate and triacetate in N-methylpyrrolidone by evaporating the solvents methylene chloride or methyl ethyl ketone. The films have high mechanical properties and are able to fibrillate as a result of realization of a liquid-crystalline state. In heat stretching of the films up to 300%, structural rearrangements take place which are characterized by reorientation of rod-like structures in the direction of deformation. The finer anisometric elements located in such structures are oriented perpendicularly to the direction of stretch.

An experimental investigation of the mechanical behavior of a number of polymers in the range 4.2–240°K has been made. It has been shown that at helium temperature the Poisson ratio is governed by the free volume. It has been established that the dynamic Young's modulus and shear modulus of these polymers at 4.2°K depend on the chemical structure: their values are determined by the mean distance between neighboring macromolecule chains.

A procedure has been developed for direct study of the kinetics of structural changes in fibres during swelling in various liquids which used ultrasound. The possibility of using the ultrasonic method to study structural changes in fibres of various chemical structures during swelling has been demonstrated.

The nature of relaxation processes in two types of hydrocellulose fibres has been examined, plus their connection with strength properties.

The frequency and temperature dependences of PABI yarn lifetime under repeated extension deformations have been investigated.

It is possible to increase the molecular orientation in POD fibres by using orientation actions on the spun fibre in the section which is most favorable for polymer orientation.

The temperature dependences of the tangent of the mechanical loss angle, tan δ, the dynamic shear modulus, G', and the velocity of shear waves, ct, of arimide PM fibre have been studied by the method of free twisting oscillations in the temperature range 20–900°K, at frequencies of 0.2–1 Hz.

Five relaxation transitions have been detected for PABI rigid-chain polymer by the method of dynamic mechanical losses, at 50, 140, 220, 380, and 480°C. An effect of relaxation transitions on the temperature dependence of strength has been demonstrated.