The empirical equation obtained can be used for designing a flocculated yarn with a given nap cover density. The optimum values of the process parameters for applying nap established as a result of the studies can be the basis for RFPs for designing and manufacturing the unit and process for electroflocculation of yarns.The essence of yarn electroflocculation technology consists of application of short-cut (0.5-1.5 mm in length) specially processed chemical yarns on adhesive-coated core yarn [1]. The area of application of the flocculated yarns and items made from them is for household and industrial textiles.We developed the optimum process conditions for application of nap to an adhesive-coated core yarn. The experimental setup assembled in the research laboratory for Friction Processes in Spinning in the Department of Wool Technology was used to fabricate the flocculated yarn. The setup contained units for unwinding the core yarn and applying the adhesive, a flocculation chamber, a drying chamber, a device for winding the yarn on a cylindrical bobbin, and a kinematic unit [2].The components of the flocculated yarn were polyamide complex elastic core yarn with a linear density of 15.6 tex; dyed polyamide floc with a linear density of 0.33 tex and average length of 1 mm, diameter of 0.019 mm, and 4% moisture content; adhesive -a three-component composite based on the water-dispersion adhesive system Tubvinyl LC 274 H-N and Tubassist Fix 106 W from CHT (Germany): 48% adhesive made from acrylic resin; 16% fixative (pH regulator); 36% distilled water. The characteristics of the composite are: initial viscosity of 9.3 Pa⋅sec; mass fraction of nonvolatiles (dry residue) of 20%; pH 7.5-8; exposure time of 2 min; ionogenicity: cation-active; conductance of 0.6⋅10 -2 Ω -1 ⋅cm -1 . The electroflocculation process was optimized with a two-factor experiment with a Kono matrix.Nap density n (1/mm 2 ) -the number of fibres per 1 mm 2 on the surface of the core yarn -was used as the optimization criterion Y. The nap density is a characteristic quantitative measure of the optimality of electroflocculation and is a function of the degree of orientation of the fibres in an electric field -was used as optimization criterion Y. On the other hand, the wear resistance of the flocculated material is a function of the nap cover density, and in this sense, the nap density is the most important qualitative characteristic [1].The specific floc consumption P sp [g/(sec⋅m 2 ] -the mass of floc fibres fed per second per area of flocculator feed grating, and working voltage U (kV) fed to the flocculator charging electrode were selected as input factors X 1 and X 2 . These factors are the most important physical process parameters directly in the flocculation working zone which affect the density of formation of the nap covering on the flocculated yarn.The specific floc consumption was regulated by varying the vibration frequency of the flocculator in the flocculator grating with 0.8 × 0.8 mm cells. The voltage on the flocculator charging ele...

The following suspension composition is recommended for fabricating yarn by the hydrodynamic method: 3 g/liter methylcellulose; 2 g/liter Laprol 5003; 2 g/liter aluminum oxide fibre. It is useful to remix the suspension directly during use, providing the corresponding technical agents for realizing this condition in the yarn manufacturing setup.The hydrodynamic spinning technology developed together with researchers at MSTU and VIAM infers the use of a suspension as the working medium, where aluminum oxide fibres are the solid phase. Suspensions of this kind must contain uniformly distributed aluminum oxide fibres and not form a coagulation structure [1].Fibre-based suspensions are coarsely disperse systems with sedimentation instability due to the content of large particles which easily overcome Brownian motion and form sediments in a short time. The particle sedimentation rate can be reduced by increasing the viscosity of the dispersion medium. Methylcellulose is frequently used for this purpose, as it has an elevated thickening effect without negatively affecting the fibres and without cross-linking. The elementary unit of methylcellulose is described by the following formula:Methylcellulose is dissolved in water after preliminary swelling at room temperature. The viscosity of the solution as a function of the concentration of methylcellulose is shown in Fig. 1.The aggregate stability of the dispersions was determined by formation of stabilizing adsorption layers consisting of ions forming an electric double layer (electric stabilization factor) or adsorption layers of surfactants (SF) or polymers that form a protective gel layer on the surface of the particles (structural and mechanical stabilization factor).There is no published information on stabilization of dispersions of aluminum oxide fibres. For this reason, we reviewed the literature in which stabilization of dispersions of clays closest to aluminum oxide fibres in chemical composition and properties (high asymmetry factor) was investigated. We found that the oligomeric SF Laprol 5003, a branched copolymer of ethylene oxide and propylene oxide, was the most effective stabilizer of clay suspensions.The above components were used as the most appropriate for developing the composition of the liquid subsequently used in the hydrodynamic method of manufacturing yarn from aluminum oxide fibres.An experiment was conducted with the second-order central composition design method to substantiate the composition of the suspension [1].Samples of the suspension were collected from the liquid 1, 5, and 15 min after it was prepared. The suspension was sampled with a specially shaped sampler with a volume of 2 cm 3 at a distance of 70 mm from the surface of the liquid. The quality criterion for the suspension was the number of aluminum oxide fibres in the sample 1 min (n 1 ), 5 (n 5 ), and 15 min (n 15 ) after preparation. The samples were analyzed in the observation field of a digital microscope at 350× magnification. A typical photograph of the fibres is shown in F...

The optimum concentration of emulsion for oiling thread from high-melting alumina fibres is established. The electrokinetic potentials of the fibre surface and oiling emulsion of the optimum concentration are determined. The optimum oiling agent concentration and rupture (tearing) properties of thread are found to be correlated.In order to facilitate textile processing, threads from chemical (synthetic) and natural fibres are submitted to treatment with textile-ameliorating agents. One of such methods is oiling dry thread before twisting. Oiling agents can be used as water-free oil composites (blends) or as aqueous emulsions.Several works were dedicated to the study of the influence of oiling composites on the thread strength [1-4]. The formulas and the methods of application of oiling composites for complex threads from high-melting (refractory) ceramic fibres, cited in patents [5][6][7], are of a descriptive nature; specific information about the composition and conditions of application are not provided.The purpose of this work was to determine the influence of the concentration of the preparation AVIV-B, UN 3082 (Technical Specification 2484-054-17965-829−2005) produced by the research and production firm Traskon on the strength of twisted threads from high-melting alumina fibres and to find the optimum oiling emulsion concentration. This oiling agent is a blend of mineral oils and surfactants. It is intended not only for enhancing the strength of twisted complex thread, but also for rendering elementary fibres selective. Since the oiling agent contains surfactants, we considered it expedient to determine their critical concentration for micelle formation (CCM) because precisely at this concentration emulsion drops are absorbed best on the hard fibre surface and the emulsion itself is most stable.The physical and chemical characteristics of oiling agent solutions of various concentrations are adduced in Table 1. Since the surfactants contained in the oiling agent exhibit their properties to the maximum at critical concentration for micelle formation (CCM), it was established by conductometric method that for the studied composition CCM comprises 8 wt.%.The correlation between the specific electric conductivity of the emulsion of the oiling compound AVIV-B and the concentration is depicted in Fig. 1. This micelle-forming concentration of 8 wt.% was confirmed also by the methods of CCM determination in terms of the dependence of the viscosity of the emulsion solutions and their surface tension on the concentration (Fig. 2).

Ceramic fibers produced in the form of multi-filament filament fibers are not strong enough to be used directly as a structural material. Factorial experiment planning is used to obtain a regression equation that describes the dependence of the absolute breaking load of a filament with a linear density of 100 tex on the degree of twisting when the initial 10-tex filament is doubled to form two strands and then five strands. The optimum degree of twisting is determined through the use of evolutionary planning.Materials composed of fibers based on high-melting oxides of aluminum and silicon can be effectively used in aggressive media heated to high temperatures [1].Ceramic fibers produced in the form of multi-filament filament fibers are not strong enough to be used directly as a structural material. One technological means of increasing the strength of these products is multiple doubling that involves twisting of the components of the fiber.The goal of the study being discussed here was to optimize twists of filament fibers. The study was performed by conducting a factorial experiment [2] that employed evolutionary planning [3].The breaking load of the fiber was chosen as the optimization criterion. Tests were performed on a mockup of a unit that provides for the doubling, twisting, and lubrication of fibers. The mockup made it possible to regulate the rate of feed of the fiber, the direction of the twists, and the number of twists. The lubrication unit made it possible to control the amount of lubricant that was supplied.The breaking load was determined using an "Instron" instrument on specimens with a test base of 500 mm. Table 1 shows the factors that were varied and their levels (the notation used here and henceforth corresponds to that employed in [2]). Table 2 presents raw data from the tests. The results obtained from calculation of the regression coefficients are shown below: b 0 = 8.36; b 1 = 0.90; b 2 = 1.16; b 12 = -0.06; b 11 = -2.924; b 22 = -0.989.We determine the variance of the absolute breaking load, or the variance of reproducibility:S 2 {Υ} = S ö 2 {Υ} = 2.8145/5 -1 + 0.70.We determine the variances of the regression coefficients:S 2 (b 0 ) = 0.2 ⋅ 0.7 = 0.14; S(b 0 ) = 0.374; S 2 (b i ) = 0.125 ⋅ 0.7 =0.0875; S(b i ) = 0.296;

An experimental setup with a differentiated thermofixation unit that ensures autoadhesive bonding of fibres was developed, assembled, and tested. The optimum thermofixation conditions were substantiated based on the criteria of the absolute breaking load, relative elongation, modulus of elasticity, and capillarity.Fibre filters fabricated by winding yarn in a cartridge have an unstable structure so that fibres are washed out during filtration of the liquid.A blend of 40% polypropylene (linear density of T f = 0.33 tex, length L f = 60 mm) and 60% lavsan fibres (T f = 0.44 tex, L f = 51 mm) was used to increase the stability of the structure of the yarn.The yarn technology provided for loosening and picking, emulsification (with 5% aqueous solution of OS-20 in the amount of 2% of the weight of the fibres), texturing and drawing, and roving. The yarn developed, with a linear density of 290 tex, had a twist of 100 tw./m. The plan for