Comparative analysis of the characteristics of supramolecular structures of dry and swollen cotton fibers makes it possible to differentiate structural regions accessible to water. The revealed features of water desorption from cotton cellulose (exceptionally low rates at the final stages, presence of residual moisture) are related to the removal of water, which is localized in the regions of the crystalline phase disorganized upon drying. The fact of incomplete moisture removal from cotton fibers at T < 325 K is interpreted from the stand point of the frozen molecular mobility in the microsurroundings of sorption sites, which are located at the defects of crystallites, at the final stage of the desorption process. A marked contribution from the recrystal lization of disorganized regions in the surface layer of crystallites to the thermal effect of the interaction between water and cotton cellulose at low water content is established.

and A. P. MoryganovIt was shown that the increase in the accessibility of cotton cellulose to water in drying is due to perturbations of the long-range order in the surface layer of crystallites. The necessity of quantitatively considering the structural changes in calculations of sorption values was demonstrated. The correlation of some features of the sorption behavior of cellulose materials in processes that include frequently repeated wetting and drying operations with the probable character of formation of accessible sections in the surface layer of the crystalline phase was noted.Studying the cellulose-water system has sustained continuous interest for many years. Information on this is important not only because of its theoretical value, but it also has direct practical significance, since cellulose materials are in close contact with aqueous and water-vapor media, primarily with atmospheric moisture, in all stages of production, processing, and use. Valuable information on the reaction of the components of the system is obtained in analyzing the water-vapor sorption isotherms for cellulosic materials [1]. Calculations of the different sorption characteristics using these isotherms usually assume constancy of the content of sorbing regions in the cellulose during water absorption. Moreover, the effect of a change in the supramolecular structure of different cellulosic materials during wetting has been reliably established with different methods of investigation (x-ray structural analysis, IR spectroscopy, dilatometry) [1][2][3][4]. The important effect of the moisture content on the ratio of amorphous and crystalline phases in cellulose should undoubtedly be reflected in the equilibrium and kinetic characteristics of its reaction with water. In this research, we established the cause of the dependence of these features of the sorption behavior of cotton cellulose which are related to the structural rearrangements that take place when the moisture content changes.The sorption measurements were performed by vacuum gravimetry using a quartz spring. We investigated scoured and bleached cotton fabric; samples of this fabric had previously been used in x-ray diffraction studies [4,5]. This make it possible to use the established parameters of the supramolecular structure in calculations of the sorption characteristics.The reaction of oxidation of cellulose with atmospheric oxygen at 150°C was also used to study the character of the structural changes that take place when cotton cellulose is wet and dried. The degree of thermooxidative degradation of the samples of cotton fabric was evaluated with the yellowness parameter, defined as coordinate b of the color field of the CIE Lab colorimetric system. It was calculated with the spectral reflection curve of thermooxidized samples taken on a reflection spectrophotometer in the 400-700 nm wavelength range.The water-vapor sorption isotherm for the investigated fabric sample at 20°C is shown in Fig. 1. In determining such a sorption value as the average hydration numbe...

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The expediency of modifying short flax fibre for production of industrial and medical materials was evaluated. The level of transformations in the flax fibres during their modification was demonstrated. The basic trends in the practical implementation of research results were presented.Technologies for production of materials for industrial, medical, and special applications based on domestic flax fibres have now entered the "critical" list and are priority directions in the development of science and technology.Obtaining high-quality, profitable products and cellulose raw material from flax processing wastes (scutching, short flax fibres) is of primary importance, since their inefficient use reduces the economic indexes of flax production. The imperfect primary processing equipment and recently observed coarsening of the flax fibres (increase in the metric number by 2 times, increase in the filament diameter by 1.3-1.4 times, rigidity, noncellulose contaminant content) [1] has resulted in the fact that of the entire volume of fibre separated (25-30% of the weight of the flax stock), no more than 1/3 is suitable for processing textile articles. The remaining low-number raw material is not completely in demand.However, ensuring profitability for flax plants primarily by sale of long flax fibre makes the enterprises in the agroindustrial complex extremely vulnerable. The artificial decrease in the price of long flax fibre to a catastrophically low level (due to imports of similar fibre from China at dumping prices) increased the amount of unsold Russian long flax and consequently exacerbated the crisis in the Russian flax complex. Overcoming the crisis will require changing the strategies for production and use of flax raw material.The results of many studies by different specialists (chemists, economists, process engineers) suggested that exhaustive processing into a primarily new line of articles is one of the main directions in reducing the cost of flax products. The economic calculations show that in comprehensive, efficient use of all kinds of flax raw material (long, short fibres, scutch), the profit from product sales increases significantly, while the profitability is greater than 30% [2].Data is presented in the present article on the technologies developed at the Institute of Chemistry of Solutions (ICS RAS) for modifying flax fibres that allow industrial production of new, not previously produced, high-quality consumer goods and industrial goods from low-number flax.Investigators have been concerned with questions of altering (modifying) flax fibres for a long historical period, more precisely, since 1665, and current studies belong to the fourth stage of development of this direction [3]. Note that the purpose of modification of flax in the first three stages was to change its spinning properties, while the last period is characterized by a large variety of studies and solvable problems.The similarity of cotton and flax filaments stimulated the idea of converting the flax fibre into a cottonized "cotton...