Hydraulic resistance of a deformable layer of fibrous material

Filtration of spinning solutions, spinning bath, and finishing solutions through a layer of fibrous material is widely used in different chemical fiber plants. In finishing of textile fibers on spools and cakes, the liquid is filtered through a layer of fiber attached by winding. At the same time, filtration is through a layer of unattached, freely packed fibrous material with random orientation of the individual fibers or through layers of nonwoven material in filtration on filters with a metal — gauze — asbestos gravity layer, in fiber finishing or modification processes, and in processes involving ion-exchange, chemisorption, and catalytically active fibrous materials.Moscow State Textile Academy. Translated from Khimicheskie Volokna, Vol. 25, No. 1, pp. 13–15, January–February, 1993.     

Optimization of the spinning solution preparation process in the manufacture of polyvinyl chloride fibre

Conclusions The effect of spinning solution preparation parameters on the fibre preparation process and on the properties of polyvinyl chloride fibre have been studied using the experiment planning method.It has been found that the concentration and holding time of the spinning solution exert the greatest effect on the process of washing the fibre free of dimethylformamide.An optimization of the parameters of preparing a solution for polyvinyl chloride fibre production under manufacturing conditions has been carried out.Translated from Khimicheskie Volokna, No. 1, pp. 24–25, January–February, 1988.     

Increasing the linear density uniformity of yarn spun from an aggressive solution

Conclusions It has been found experimentally that to increase the uniformity of linear density of yarn spun from an aggressive spinning solution of 40–50 Pa·sec viscosity, it is necessary to use metering pumps of high output and to maintain a positive pressure difference of up to 1 MPa between the spinning solution pressure at intake and that at discharge from the pump.A new candle filter construction has been proposed for maintaining a positive difference between the spinning solution pressure at intake and at discharge.Translated from Khimicheskie Volokna, No. 1, pp. 40–41, January–February, 1986.     

Manufacture of Granulated Chitosan

Conditions for dry-wet spinning of spherical chitosan granules 0.5–2.0 mm in diameter into a two-layer spinning bath consisting of immiscible liquids are proposed, where an organic liquid, decane in particular, is the upper layer of the bath while a solution of ammonium hydroxide is the lower layer. The possibility of obtaining chitosan microgranules from 2 to 30 µm in diameter by emulsification of a solution of chitosan in decane or a solution of an anion-active surfactant — sodium dodecyl sulfate — is demonstrated. The effect of the molecular weight and concentration of the solutions on the granule-forming power of chitosan is established. A 6% solution of chitosan with a molecular weight of 200 kD is recommended for further studies.__________Translated from Khimicheskie Volokna, No. 5, pp. 26–29, January–February, 2005.     

Quantitative determination of the low-molecular fraction content of spinning solutions of poly-meta-phenyleneisophthalamide

Conclusions A method for the quantitative determination of low-molecular fraction content in spinning solutions of poly-meta-phenyleneisophthalamide in dimethylacetamide has been established and developed using UV-spectroscopy; this is a basic procedure.The effect of the composition of the reaction mixture on the LMF content of the spinning solution has been shown.VNIISV, Tver'. Translated from Khimicheskie Volokna, No. 2, pp. 17–19, March–April, 1992.     

Determination of acid impurity content in spinning solution and in freshly spun fibre made from aromatic polyamides

Conclusions The spinning solution from the manufacture of fibre from an aromatic polyamide contains dissolved HCl in the free form and HCl bonded to functional groups of the polymer; the freshly spun fibre contains only bonded HCl.A procedure has been developed for determining the content of free and bound HCl in spinning solution and freshly spun fibre; it is based on titrating a sample of a specimen in a medium of dimethylacetamide containing 3% LiCl with an approximately 0.04-molar alcoholic KOH solution.Translated from Khimicheskie Volokna, No. 2, pp. 58–60, March–April, 1990.     

Mathematical modeling and calculation of the spinning solution filtration process in the manufacture of man-made fibres

Conclusions A generalized filtration equation has been obtained, which permits one to carry out mathematical modeling of a broad class of filtration processes of spinning solutions of fibre-forming polymers; it has low values of the error in approximation.On the basis of the results of mathematical modeling, a procedure has been worked out for evaluating the complex mechanism of the filtration process, using which it is possible to carry out a comparative analysis of the experimental data and to take into account (quantatively) the effect of technological conditions on the filtration process.The extremeness of the behavior of the basic characteristics of filtration equipment as a function of change in filtration rate, which characterizes the operating regime of a filter, has been demonstrated.The use of the magnitude of specific costs as an optimicity criterion in designing and rational construction of filtration schemes is soundly based.Program provision has been devised for calculating and making an analysis of the characteristics of apparatus design in the stage of filtering spinning solutions of fibre-forming polymers using a computer for projected and operating man-made fibre manufacturing.Translated from Khimicheskie Volokna, No. 2, pp. 24–27, March–April, 1985.     

Special features in spinning cuprammonium fibres into aqueous-organic baths

Conclusions A number of aqueous—organic baths which are usable in spinning cuprammonium fibres have been studied.It has been shown that the composition, precipitating power of the precipitation bath, and spinning conditions predetermine the physicomechanical properties of cuprammonium fibres.Translated from Khimicheskie Volokna, No. 5, pp. 18–20, September–October, 1984.     

Modification of polyacrylonitrile fibre with hydrolyzed wastes

Conclusions Principles governing the alkaline hydrolysis of wet Nitron fibre waste and their solubilities in 51.5% aqueous sodium thiocyanate solution have been studied. It has been found that the best solubility is attained at an SEC of 0.17–0.20 meq/g. The solutions obtained on addition of these wastes are characterized by reduced viscosity, better filterability, and a reduced gel-particle content.It has been found that stable spinning and preparation of fibre with better physicomechanical characteristics are achieved when 5% by wt. of the hydrolyzed products is added to the spinning solution.Translated from Khimicheskie Volokna, No. 1, pp. 10–11, January–February, 1989.     

Effect of electric heating on ripening of viscose

Ripening of viscose in heating with an industrial-frequency electric current was investigated. It was shown that an effect of homogenization of the viscose is obtained with the electric current. It was found that when viscose was heated with an electric current, in contrast to use of heat exchangers, the minimum viscosity and concentration of gel particles was preserved during the time required for deaeration and filtration. This will allow obtaining a spinning solution with optimum physicochemical properties for spinning.Siberian Institute of Technology, Krasnoyarsk. Translated from Khimicheskie Volokna, Vol. 25, No. 1, pp. 18–19, January–February, 1993.     

Operative control of the polymer solution filtration division

Conclusions An approach to the construction of an optimum control system for multistage schemes for cleaning-up spinning solutions under conditions of appreciably nonsteadiness of the filtration process has been examined.The control problem has been formulated and the basic stages in its solution have been set forth, based on the results of mathematical modeling of the process and formalizing the decisive links.A standard functional structure of the system of operative control of the filtration division as a subsystem of the ACS TP for man-made fibre plants is given.Program and mathematical assurance for realizing the control system examined have been developed, using computer control technique.Translated from Khimicheskie Volokna, No. 5, pp. 29–32, September–October, 1986.     

A rapid method of determining the aromatic polyamide content of dimethyl acetamide

Conclusions -- A rapid method of determining the polymer content of spinning solution in the concentration range from 7–20% by wt. has been developed; it is based on precipitation of the polymer in acetic anhydride, extraction of the solvent, and subsequent titration of it with perchloric acid. A comparison of the results obtained using the rapid procedure and the dry residue method has been carried out.-- The procedure developed is characterized by accuracy and rapidity in the determination.Translated from Khimicheskie Volokna, No. 5, pp. 59–60, September–October, 1990.     

The problem of refining cellulose triacetate solutions with fibrous ion-exchange resins

Conclusions The process of cleaning up cellulose acetate spinning solutions and model solutions from traces of acid dyes with polyacrylonitrile fibre anion-exchangers has been investigated. Optimum conditions for carrying out the clean-up have been determined.It is recommended to use ion-exchange resin type PAN(2)cp-PEA, prepared using a polyamine preparation, to clean up the spinning solution.Translated from Khimicheskie Volokna, No. 5, pp. 16–17, September–October, 1985.     

Effect of the conditions of spinning of polyester fibres on the longitudinal velocity gradient

The velocity gradient changes as a function of the conditions of spinning PETP, and the value can increase from several tens to hundreds of units in the order LSS (low-speed spinning)—MSS (medium-speed spinning)—HSS (high-speed spinning). A combined increase in the longitudinal velocity gradient, orientation, and relaxation time is observed with an increase in the speed of spinning PETP. It was shown that crosslinking of PETP is determined by the character of the strain in the longitudinal velocity gradient field. The features and common points of spinning of PETP monofilament and complex fibre and their cross-linking in a longitudinal velocity gradient field were determined.All-Russian Scientific-Research Institute of Synthetic Fibres, Tver'. Translated from Khimicheskie Volokna, No. 5. pp. 30–33, September–October, 1996.     

Use of diluted viscose waste in the process of preparing complex yarn for aircraft fabrics

Conclusions The possibility has been established of using dilute viscose wastes in the process of preparing a spinning solution for spinning complex viscose yarns which are used in the manufacture of aircraft fabrics.Empirical equations have been obtained for calculating the change with time of ripeness indices and of free NaOH content of viscoses having an -cellulose concentration of 5.0–8.4% by wt., plus calculated dependences which ensure determining the optimum ripeness index for spinning for viscoses which have been diluted in the range indicated.It has been shown that, with decrease in -cellulose and NaOH content of the spinning solution, the stiffness of complex viscose yarn is increased.Translated from Khimicheskie Volokna, No. 3, pp. 48–50, May–June, 1986.     

Change in structure of polypropylene during processes of fibre spinning by the high-speed method

Conclusions Conditions for preparing polypropylene fibres from polymers of various structural modifications, orientations, and crystallinities at spinning speeds of 1000–5000 m/min have been studied experimentally.The investigated fibres are characterized by a high degree of crystallinity and orientation of the crystalline regions.Depending on fibre spinning speed, a transition is observed through definite morphological structures — from spherulitic to a typical fibrillar structure, which is formed at very high spinning speeds.Translated from Khimicheskie Volokna, No. 6, pp. 47–49, November–December, 1989.     

Preparation of ftorlon fibre filled with manganese dioxide

Conclusions The possibility of obtaining catalytic fibres by introducing the catalyst as a filler into the structure of Ftorlon fibre has been established.Sorptive properties of Ftorlon fibre spun in the absence of filler as a function of the amount of polyethylene glycol added to a spinning solution of the fibre-forming polymer and of the spinning conditions have been investigated, as well as the morphology of the surface of the modified Ftorlon fibre.It has been discovered that, by choosing the composition of the spinning solution and the conditions of spinning Ftorlon fibre filled with manganese dioxide, it is possible to obtain a fibre having a porous structure which ensures accessibility of the filler to reagents.Translated from Khimicheskie Volokna, No. 2, pp. 31–33, March–April, 1988.     

Effect of surface-active substances on the fibre-forming process and properties of nitron fibre

Conclusions The effect of surface-active agents on the surface tension of polyacrylonitrile (PAN) spinning solutions has been studied.It has been found that introducing SAS into the precipitation bath increases fibre-formation stability. The use of SAS as modifying additives to the spinning solution and into the precipitation bath leads to an increase in the uniformity of spun fibre properties.The possibility of reducing the linear density of Nitron fibres on introducing SAS into the spinning solution and the precipitation bath has been demonstrated.Translated from Khimicheskie Volokna, No. 3, pp. 24–26, May–June, 1985.     

Analysis of the stability region of the process of spinning yarns based on aromatic polyamides

Conclusions -- For fibres based on aromatic polyamides at a constantv ₁/v ₀ ratio, the coefficient of jet expansion * remains practically unchanged with increase in flow rate, since thereupon the force of yarn tension rises considerably.-- As a result of analysis, a region of stable spinning has been determined by the ratio of the plasticized stretch and the tensions in the yarn in the region around the spinneret.-- The range of allowable change in parameters in the region of stable spinning depends on the viscosity of the starting polymer solution. This range diminishes with rise in viscosity.-- A procedure for analysis of spinning regimes has been proposed which permits one to estimate the maximum allowable rate of polymer solution outflow that ensures stability of the process at an assigned level of spinneret and plasticized stretches.Translated from Khimicheskie Volokna, No. 1, pp. 24–27, January–February, 1991.     

Increasing the dyeing uniformity of viscose textile yarn

Conclusions The possibility of significantly raising the dyeing uniformity of viscose textile yarn by activating the cellulose and by selecting technological spinning parameters which ensure maximum yarn shrinkage before its arrival at the centrifuge has been shown.It has been found that, with increase in the ability of the freshly spun yarn to shrink, its dyeing uniformity is reduced.The dyeing uniformity of viscose yarn prepared by the centrifugal method can be raised by changing its shrinkage on the spinning machine during the spinning process, by activation of the cellulose, and by choosing a precipitation bath which is very suitable for spinning viscose yarns from activated celluloses.Translated from Khimicheskie Volokna, No. 2, pp. 41–42, March–April, 1984.