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It was shown that modified surgical sutures with a coreshell structure with assigned thickness and porosity of the polyhydroxybutyrate shell or mixtures with other polymers and SF additives can be fabricated. It was found that a change in the content of the modifier polymer in the fibres within the limits of up to 15% had almost no effect on their metric size and strength. The dependence of the rigidity of the sutures on the modifier polymer content is described.Surgeons now have a wide assortment of surgical sutures that differ both in the composition of the raw material (polyamide, polypropylene, poly(ethylene terephthalate), natural silk, polyglycolide, polylactide, etc.) and in the structure (monofilaments; multifilament twisted, braided surgical sutures), but only two indexes have been standardized the thickness and strength of the sutures [1,2]. According to the European Pharmacopedia, the strength is determined by the breaking load of the suture tied in a simple (single) knot and is expressed in newtons. The thickness of surgical sutures is characterized by the metric size (MS) and is determined by the range of parameters in which a suture of a given standard size falls [1].* However, such properties of sutures as pliability, elasticity, atraumaticity, low capillarity, bactericidal action, biocompatibility, and in many cases biodegradability are no less important. They ensure convenience in application of the suture and its reliability; lack of a sawing action on the tissue, sorption of wound content, and infection; correspondence of the deformation properties of the sutures to the topography of the tissues with an increase in the volume of the suture in the stage of edema and a decrease in the subsequent stages of healing. In tying knots, the surgeon must take into consideration the structure and surface properties of the suture. For example, we know that twisted and braided sutures have greater surface roughness than monofilaments and for this reason ensure a more reliable suture when less complex knots are used, but these sutures traumatize the tissue more [3]. At the same time, monofilaments and more rigid and elastic and require using more complex knots than multifilament sutures.Creating composite sutures with a coreshell structure is an effective way of fabricating surgical sutures that combine the softness of multifilament sutures and the smooth surface of monofilaments [4,5]. Application of a coating on the surface of the sutures allows regulating the flexibility, surface roughness, and knot reliability, giving multifilament sutures atraumaticity and decreased capillarity, changing the color, and incorporating drugs, antimicrobials in particular, in the suture. In this way, coated sutures represent a balance between the qualities of mono-and multifilament sutures.A biodegradable complex polyester polyhydroxybutyrate (PHB), is of some interest as a modifier polymer [6], and its production technology, developed at the A. N. Bakh Institute of Biochemistry, Russian Academy of Sciences, has now been ma...

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Chitin, one of the most widely distributed polysaccharides in nature, is of great interest as a fibre-and film-forming polymer. The possibility of processing chitin and its derivatives into fibres and films is determined by the properties of their solutions. The structure of chitin allows obtaining derivatives containing a unique set of functional groups -neutral hydrophilic and hydrophobic and ionogenic and acid and basic -by simple chemical transformations [1, p. 115]:For example, it is only possible to obtain polybase chitin (II), polyacid carboxymethylchitin (III), and polyampholyte carboxymethylchitosan (IV) by a combination of treatments of chitin (I) with sodium hydroxide and monochloroacetic acid [2, 3].In contrast to chitin, its derivatives II-IV dissolve in aqueous media, and this greatly facilitates their use in the form of solutions in cosmetics and food products and processing them into films, fibres, granules, etc. It should be noted that chitosan only dissolves in acid (pH < 5) aqueous media, carboxymethylchitin (CMCT) dissolves in almost the entire pH range, carboxymethylchitosan is soluble in pH < 3.5 and > 6.5, and in the range of pH 3.5-6.5, an insoluble inner salt of the polyampholyte is formed [2, 3].The properties of solutions of chitosan, primarily dilute, have been described in many studies [4][5][6][7][8]. The contradictory data noted in [4, 6, 8] are due to the important dependence of the properties examined on the methodological approaches and conditions of conducting the experiment. There are only isolated studies of the rheological properties of solutions of carboxymethylated derivatives of chitin and chitosan [9][10][11]. The properties of dilute and concentrated solutions of chitosan and carboxymethylchitin as two of the most easily obtained derivatives of chitin of promise for practical use as thickeners, and moisture-retentive and film-forming additives in therapeutic and decorative cosmetics and food products are compared in the present article.Pilot industrial samples of chitosan from Sevryba VRPO and laboratory samples of CMCT synthesized by the method in [12] were used ( Table 1).The concentration of primary amino groups was determined by the Van Slyke method [13, p. 164] and potentiometric titration; carboxyl and N-acetyl groups were determined by IR spectroscopy [ 14]. An RTS 822 (from Radiometer) automatic titrator was used for potentiometric titration. The IR spectra of solutions of polysaccharides in heavy water (pD --0.8) were recorded on a Specord M-80 (Carl Zeiss Jena).Moscow State Textile Academy.