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In determining the adhesive-self-adhesive interaction of particles of disperse fibre-forming polymers, it is necessary to consider the nature of the forces that cause it, the structural and mechanical properties of the contacting surfaces (roughness and possibility of deformation in the contact zone, which affect the contact area of the polymer particles with the surface; the porosity of the materials; the existence of a gap between contiguous bodies, the radii of curvature of the contacting bodies), as well as the shape of the processed particles.The adhesive-self-adhesive properties (ADSP) that determine the interaction of contiguous condensed bodies are important in modern manufacturing processes. In chemical fibre production technology and in processing fibre-forming polymers, adhesive-self-adhesive properties are important in extruder processes, operation of dust-removal hopper systems, loading and unloading units, drying of polymers, etc. In particular, it is necessary to consider the ADSP of the processed materials, i.e., the effects of sticking to the walls of the unit, caking, etc., which prevent the normal evolution of drying of disperse fibre-forming polymers, to correctly select the dryer and equipment design, especially the feeders and batchers. Disperse fibre-forming polymers were classified to evaluate ADSP, and ADSP was taken into account through the adhesive-cohesive coefficient (K a ), related to the angle of repose of a disperse material [1][2][3][4][5]. The corresponding equation iswhere ƒ is the internal friction coefficient. For practical use, rating of K a , evaluated in points (from 1 to 5) characterizing the degree of friability or stickiness of the material (an ideally friable material, the sand in hourglasses, for example, has K a = 1, and for a sticky, wet, paste, wet clay, for example, K a = 5), is taken into account.At a certain stage in the evolution of manufacturing and production processes, this classification undoubtedly played an important role. However, it includes gradation of the treated materials, primarily by the organoleptic method, and does not reveal the mechanism of the adhesive-self-adhesive interaction of disperse particles and does not allow numerically determining the strength of the adhesive-self-adhesive interaction of contacting bodies. For this reason, the need for a theoretical approach to the numerical evaluation of ADSP of processed materials, including disperse fibre-forming polymers, is increasing.The adhesive-self-adhesive interaction on contact of particles (with the walls of the unit and with each other) is due to forces of different natures [6,7] which are a function of the surface properties of the fibre-forming polymers and the contact area. Self-adhesion, which determines the strength of the interaction between homogeneous particles that cause the particles to stick to the processed materials (caking), can be considered as adhesion of the second kind, which is not manifested on a surface of a different nature (for example, particles sticking to the w...

The hygiene and comfort of clothing are determined to a significant degree by the hygroscopicity of the fibres from which they are made. Natural fibres such as wool and cotton have elevated hygroscopicity and are in high commercial demand. Viscose fibres and the new fibre Togilen [1][2][3], created at the Khimvolokno LenSRI also have good water absorption. The mechanical characteristics of the articles are also a function of the hygroscopicity of the fibres and threads.Finishing processes are also a function of the hygroscopicity of the materials to a significant degree. Knowledge of the equilibrium moisture content of materials at different temperatures and relative humidities is required, for example, in calculating the drying parameters of these materials.In studying the sorption properties of fibres, thread, and textiles [I], their sorption characteristics are determined in standard conditions (relative humidity ~, of 65 + 5 %, temperature of 20 + 2"C). The standard indexes of the moisture content W and hygroscopicity of textiles are determined for ~, = 65 and 98 % [1].The sorption-desorption isotherms plotted for the complete range of variation of ~o most completely characterize the hygroscopicity of materials. There is still no rigorous theoretical description of the sorption-desorption isotherms. A semiempirical theoretical probability equation of equilibrium sorption [1, 4], used for ,t, of up to 95 % (i.e., to the beginning of capillary condensation), is recommended in [1] for calculation of equilibrium sorption-desorption. However, it contains a number of difficult to determine parameters which are calculated by computer software in [1]. In routine practice, it is frequently more convenient to use simpler empirical dependences which do not require complex calculations.Some investigators have noted the virtual absence of any effect of the temperature in the interval they investigated [5, 6]. At the same time, the sorption statics are determined by steady-state diffusion and as we know, the molecular diffusion coefficient is a function of the temperature to a degree of 3/2. Then there are the empirical and semi-empirical equations of Langnuir, Freundlieh, and the Russian investigators A. A. Rode, Ya. M. Miniovich, A. V. Lykov, and B. A. Posnov [5, 6], used for special cases.We proposed an empirical dependence of the following type for fibre materials with high hygroscopicityThis dependence can be used for describing both desorption and sorption isotherms. However, the latter, especially for materials with significant hysteresis of the sorption characteristics and high hygroscopicity, are better described by a dependence of the typeWe will demonstrate the possibility of using the proposed curves on the example of the isotherms of the four types of fibres listed above; these convex-concave shapes of the isotherms are characteristic of textile materials. The experimental points from [2] and paired isotherms for cotton (lower) and viscose fibre (upper) are shown in Fig. la, and

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