Chemical changes in polyvinyl fluoride during the process of fibre-spinning

Conclusions The change in some properties of polyvinyl fluoride during the process of fibre spinning has been investigated.It has been found that during the process of converting PVF powder into fibre, the degree of polymer crystallinity plus its resistance to thermal and thermooxidative degradation is increased; depending on the spinning regime, the densities and physicomechanical properties of PVF fibres are different.Translated from Khimicheskie Volokna, No. 4, pp. 34–35, July–August, 1984.     

Structure of a biocatalyst fibre containing modified β-galactosidase

Conclusions A connection between the composition of the spinning solution intended for preparation of a biocatalyst fibre, the conditions of fibre spinning, and the porosity characteristics of the fibre structure has been established.The possibility of purposefully regulating the catalytic properties of a biocatalyst fibre by varying the fibre structure has been demonstrated.Translated from Khimicheskie Volokna, No. 1, pp. 21–23, January–February, 1989.     

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.     

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 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 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.     

The role of fibre diameter in preparing a heat-bonding fibrous material

Conclusions The connection of the basic technological parameters of the spinning process with structural parameters has been established for heat-bonded fibrous materials.It has been shown that the decisive structural parameter which affects the service characteristics of heat-bonded fibrous materials to the greatest extent is the fibre diameter.An equation has been found which reflects the dependence of fibre diameter on technological spinning parameters, and which makes it possible to predict the operational properties of heat-bonded materials.VNIISV, Tver'. Translated from Khimicheskie Volokna, No. 2, pp. 37–39, March–April, 1992.     

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.     

Preparation of heat-stable polypropylene fibres and their properties

Conclusions A method has been developed for preparing a modified polypropylene fibre by spinning from a mixture of polypropylene and a small amount of a thermoplastic acrylonitrile copolymer which contains a functional group which forms intermolecular chemical bonds during the fibre preparation process.It has been shown that in the given method of modifying PP fibre, its heat resistance is raised by 40–50°K.Translated from Khimicheskie Volokna, No. 3, pp. 51–52, May–June, 1985.     

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.     

Optimizing the process of filtering spinning solutions

Conclusions The question of optimizing the spinning solution filtration process with respect to a production criterion — the maximum gain in commercial production (profit) — has been examined.It has been shown methodically and experimentally that attainment of the maximum yield of fibre of highest quality as a result of increasing the cleanness of the spinning solution is attended with a deviation from the maximum profit.A procedure has been worked out, and specific example given, for calculating the optimum values of the filtration surface and charge density for typical manufacturing situations. It is recommended to use this procedure in plants which produce viscose, acetate, nitron, or other fibres.Translated from Khimicheskie Volokna, No. 6, pp. 8–12, November–December, 1985.     

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.     

Effect of aerodynamic spinning parameters and polymer properties on fibre diameter

Conclusions On the basis of theoretical calculations by a mathematical model of the process of aerodynamic spinning of polymer melts, whose adequacy has been established from experimental data, the sensitivity of final fibre diameters to change in technological spinning parameters and on the thermophysical and rheological properties of the polymer has been determined.It has been shown that among the factors which most significantly affect the final fibre diameter are the velocity of air movement in the ejector, the polymer flow rate, the temperature of the melt, the density of the melt, the viscosity anomaly, and the activation energy of viscous flow.Translated from Khimicheskie Volokna, No. 5, pp. 37–39, September–October, 1988.     

Some features of spinning hollow fibres from polycarbonatesiloxane melts

Conclusions The following parameters have been determined as a result of calculations: fibre tension, solidification path length, and the change along the spinning path of the following: stretching stresses, speed, radius, wall thickness, and fibre temperature.It has been shown that, with increase in take-up speed, the length of the section of fibre deformation is reduced, varying practically proportionally to the flow rate of the polymer system.Stability of the process of spinning hollow fibres from polycarbonatesiloxane melts is assured within a narrow range of stretching force.Translated from Khimicheskie Volokna, No. 3, pp. 41–43, May–June, 1989.     

Increasing the stability of pump operation in metering solutions of polyoxadiazole in sulfuric acid

Conclusions The basic reasons for failure in the operation of spinning gear pumps in metering solutions of polyoxadiazole in concentrated sulfuric acid have been studied.The possibility of eliminating blockage of gear pumps, reducing nonuniformity in delivery of spinning solution, and considerably increasing the stability of spinning Oksalon fibre has been demonstrated.Translated from Khimicheskie Volokna, No. 2, pp. 54–55, March–April, 1986.     

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.     

Cooling of the polymer jet in fibre spinning

Conclusions The effect of various technological parameters (jet stretch ratio, temperature and flow rate of the polymer melt, temperature and velocity of the air which cools the melt, and rheological characteristics of the polymer) on the change in temperature and viscosity of the polymer jet along the length of the spinning zone has been investigated.It has been shown that the temperature of the cooling air, the Stanton number, and the velocity of the cooling air exert the greatest effect on the fibre temperature at the take-up device, but jet stretch ratio and rheological properties of the melt affect fibre temperature only slightly.Translated from Khimicheskie Volokna, No. 6, pp. 19–20, November–December, 1987.     

Laws governing the process of spinning isotropic pitches

Conclusions -- A procedure has been developed for calculating the specific volume of the flowing zone of fibre in spinning from the melt.-- The unequivocal connection between the specific volume of the flowing zone of spun fibre and the strength of the final fibre from pitches indicates that to attain higher strength, it is necessary to create more severe conditions for fibre cooling.-- It has been found that fibres from pitches with a softening point above 200°C are more sensitive to fluctuations in parameters of the spinning process.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 41–42, May–June, 1991.     

Hollow fibre based on polyphenylene isophthalamide as the highly-porous backing

Conclusions -- The possibility of preparing a highly-permeable backing from polyethylene isophthalamide in spinning composite hollow fibres for gas separation has been demonstrated.-- A connection has been established between spinning parameters and their effect on the gas permeability of the backing.-- A regime for the preparation of hollow fibres which have an optimum morphological structure for the wall pore structure has been determined.Translated from Khimicheskie Volokna, No. 4, pp. 47–48, July–August, 1991.     

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.