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.     

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.     

Dynamic characteristics of the high-speed process of spinning polymer melts

Conclusions A procedure has been given for calculating the instability in fibre diameter under the action of technological perturbations, which is based on the use of the dynamic characteristics of high-speed process of spinning polymer melts.It has been shown that the reaction of the high-speed spinning system to stepwise perturbations is less than the reaction to harmonic perturbations at the inherent frequency of the spinning system. The range of perturbation frequencies which adjoins the inherent frequency of the spinning system is very dangerous from the point of view of instabiity in the diameter of the spun fibres.The possibility of using dynamic characteristics to base requirements on accuracy in stabilization of technological parameters in the high-speed spinning process has been examined.Translated from Khimicheskie Volokna, No. 5, pp. 13–15, September–October, 1989.     

Structure of polyurethane spinning solutions and its effect on properties of spandex fibre

Conclusions The supermolecular structure of solutions of polyurethane and of polytetramethylene ether glycol has been studied. It has been found that spinning solutions having a large content of gel-particles are obtained from a more structurized polytetramethylene ether glycol.Correlation analysis of the dependences of physico-mechanical fibre indices on parameters of the low-molecular compounds of spinning solutions has shown that the specific load and load at 300% extension vary directly proportionally to the concentration and inversely proportionally to the size of particles in the spinning solution, and shrinkage in hot water varies in the opposite way.Translated from Khimicheskie Volokna, No. 1, pp. 37–38, January–February, 1989.     

Spinning cellulose acetate fibres in a nitrogen stream

Conclusions Results of studies on the spinning of acetate yarn in a current of nitrogen, at elevated concentrations of acetone vapor in the vapor-gas mixture in the spinning tower, have been presented.It has been shown that when acetate yarn is spun under the indicated conditions, the physicome chanical properties of the fibre are improved and the residual acetone content of the freshly spun yarn is reduced.Translated from Khimicheskie Volokna, No. 1, pp. 28–29, January–February, 1984.     

Stability to the process of spinning a jet of polyacrylonitrile solution in dimethylformamide

Conclusions An experimental study of stretching resonance in spinning solutions of polyacrylonitrile in dimethylformamide has been performed, and conditions for stable spinning of these solutions has been determined.It has been shown that the mathematical model used to describe theoretically spinning process stability adequately describes this process only on the condition that the rheological characteristics are functions of lengthwise deformation rate and spinning conditions.Translated from Khimicheskie Volokna, No. 4, pp. 16–18, July–August, 1988.     

Effect of precipitation bath parameters on the spinning of viscose yarn

Conclusions A criterion for complex evaluation of the effect of precipitation bath activity on fiber-forming processes in spinning viscose textile yarn has been established.The possibility of predicting the optimum composition of the precipitation bath within a broad range of sulfuric acid and sodium sulfate content has been shown.Translated from Khimicheskie Volokna, No. 1, pp. 29–30, January–February, 1985.     

Spinning viscose technical yarn into a bicomponent precipitation bath

Conclusions -- The possibility has been demonstrated of preparing viscose yarn by the centrifugal method from a viscose containing additions of urea by spinning into a bicomponent precipitation bath containing sulfuric acid and sodium sulfate.-- Optimum conditions for spinning viscose yarn have been established: a sulfuric acid content of 115 g/l in the precipitation bath, a urea content of 2.5% based on weight of -cellulose in the viscose, and an orientation stretch of 22%.-- Specimens of viscose yarn having a linear density of 13.3 tex have been prepared with a relative breaking load of up to 19 cN/tex, an elongation at break of 17–19%, and a mean squared deviation in dyeing nonuniformity of 0.8–1.0.Translated from Khimicheskie Volokna, No. 4, pp. 33–34, July–August, 1990.     

Causes of the appearance of adhesions in the formation of cuprammonium staple fibre

Conclusions 1. It has been shown that the content of ammonia in the spinning solution and the coagulation bath, the content of sodium sulphate in the coagulation bath, and the rate of its feed to the spinning unit affect the adhesivity of cuprammonium staple fibre.2. To decrease the number of adhesions in the fibre it may be recommended that the ratio of ammonia to cellulose in the solution should be kept between 0.48 and 0.50, the content of ammonia in the coagulation bath should be not more than 0.05 g/litre and that of sodium sulphate 1.2–1.5 g/litre, and the rate of feed of the bath should be 18–20 litres/min.We express our thanks to Prof. A. B. Pakshver for valuable advice in the performance of this investigation.Ivanov Chemical and Technological Institute (IKhTI); Shui Factory. Translated from Khimicheskie Volokna, No. 3, pp. 41–42, May–June, 1969.     

Effect of orientation stretch and of jet stretch on properties of viscose fibre spun into a bicomponent precipitation bath

Conclusions The effect of orientation stretch and of jet stretch on the technological process of preparing viscose fibre from viscoses containing added urea has been studied in spinning into a bicomponent precipitation bath containing sulfuric acid and sodium sulfate.It has been shown that increasing the air stretch to 30–40% while reducing the sulfuric acid content of the precipitation bath to 80–100 g/liter and reducing the jet stretch 8 to 20% helps to improve the properties of viscose fibre.Translated from Khimicheskie Volokna, No. 4, pp. 47–48, July–August, 1989.     

Effect of technological spinning transitions on the properties of nickel-containing nitron fibre

Conclusions The effect of technological spinning transitions on the properties of an electrically-conducting metallized Nitron fibre has been investigated.It has been shown that in mechanical crimping the mechanical and electrically-conducting properties of a nickel-containing fibre are considerably impaired. During the spinning process, a considerable leveling out of the nickel content of the fibre and of its electrical resistance takes place.Processing of the nickel-containing fibre should be carried out with elimination of the mechanical crimping process. Thereupon the change in fibre properties takes place mainly during the process of preparing the combed lap.Translated from Khimicheskie Volokna, No. 5, pp. 39–40, September–October, 1985.     

Effect of moisture in polycaproamide flake and of types of melting devices on polymer properties after repeated melting

Conclusions A calculation of the equilibrium moisture content of polycaproamide flake has been given, with allowance for specific conditions of synthesis and processing on spinning machines.In processing flake with an equilibrium moisture content on machines of the extruder type, a lack of change in polymer molecular weight after repeated melting and a high chemical uniformity are assured.Translated from Khimicheskie Volokna, No. 3, pp. 44–46, May–June, 1986.     

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.     

A mathematical model of the aerodynamic method of spinning fibres from polymer melts

Conclusions The problem of spinning fibres from thermoplastic polymers by the aerodynamic method in the preparation of nonwoven materials has been formulated and realized on a computer.It has been shown that the character of change in rheological force and lengthwise velocity gradient over the spinning path length differs sharply from the corresponding quantities in the classical method of spinning polymer melts.Translated from Khimicheskie Volokna, No. 4, pp. 18–20, July–August, 1988.     

Effect of synthesis conditions on the viscosity properties of acrylonitrile copolymer spinning solutions

Conclusions The spinning solution used the high-shrinkage component in the manufacture of a bicomponent fibre based on an acrylonitrile copolymer in a structured system and has a weakly defined viscosity anomaly.An increase in initiator content, and also an increase in polymerization temperature, without changing the character of flow of the spinning composition, reduces the molecular weight of the copolymer and the viscosity of the spinning solution.An increase in the sodium thiocyanate content in the water is accompanied by an increase in the molecular weight of the copolymer and in the viscosity of the spinning solution.Translated from Khimicheskie Volokna, No. 6, pp. 15–16, November–December, 1985.     

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.     

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.     

Effect of fluctuations in polymer melt temperature of linear density of yarn

Conclusions The effect of polymer melt temperature fluctuation at the inlet to the metering pump on nonuniformity in yarn linear density has been studied.It has been shown that considerable fluctuation in yarn linear density, caused by change in melt temperature, takes place also in individual working sites.A considerable difference in the temperature of the melt going to individual working sites of machines for spinning technical yarns has been discovered.Fluctuation in the linear density of yarn caused by variation in melt temperature at the inlet to the metering pump may reach 0.3–0.8% in spinning technical yarns, depending on the construction (group or individual) of the spinning machine melting devices.Translated from Khimicheskie Volokna, No. 5, pp. 45–47, September–October, 1984.     

Preparation of polyacrylonitrile fibre by spinning into organic baths

Conclusions -- The spinning of polyacrylonitrile copolymers into organic baths containing dimethyl sulfoxide and isopropyl alcohol has been investigated. It has been found that the optimum DMSO:IPA ratio in the precipitation bath is 60:40% by wt..-- It has been discovered that the strength of the spun yarn is higher the lower the jet stretch.-- The effect of temperature on orientation stretch ratio has been studied. It has been shown that the optimum temperature for heat stretching of PAN yarn lies in the range 155–160°C.-- The dimethyl sulfoxide content of yarn has been determined by technological transitions. In the final yarn it does not exceed 0.3–1.2% by wt.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 15–16, May–June, 1991.     

Preparation of fibres from graft copolymers of acrylonitrile and polyvinyl alcohol

Conclusions The possibility of spinning fibres from graft copolymers of polyvinyl alcohol and acryonitrile by the scheme for spinning polyacrylonitrile fibre has been established.It has been shown that spinning solutions can be prepared directly from latexes of the graft copolymers.The suggestion has been made that long side chains in the copolymers participate in formation of supermolecular structural elements and aid in obtaining fibres with adequately high mechanical strength and an increased thermal stability.Translated from Khimicheskie Volokna, No. 1, pp. 13–15, January–February, 1988.