Correlation of the rheological parameters of a polycaproamide-polyethylene melt with jet expansion during spinning

Conclusions The contribution of the forces which cause a superadditive jet expansion to the force which is necessary for stretching a jet in the process of spinning from a polycaproamide-polyethylene melt has been evaluated.The correlation between the degree of jet expansion, as determined under viscometry conditions, and the degree of jet expansion in the spinning process has been established.The correlation between degrees of jet expansion is explained by the fact that, under spinning conditions, the role of a rather long capillary is played by the zone of convergent flow in the region of entrance into the spinneret hole channel.Translated from Khimicheskie Volokna, No. 1, pp. 21–22, January–February, 1984.     

Effect of spinning conditions on the stationary regime region in stretching a jet of a solution of poly-p-phenyleneterephthalamide in an air gap

Conclusions -- The spinning of a yarn from sulfuric acid solutions of poly-p-phenyleneterephthalamide through an air gap in the region of high stretch ratios is unstable because of the onset of pulsations in jet diameter, which is known for polymer melts as stretching resonance.-- The onset of resonance depends on the diameter of the holes in standard cup-shaped spinnerets in the range 0.06–0.1 mm.-- The region of stationary jet-stretching regimes without resonance is considerably expanded in the case of forced cooling of the jet of PPTA solution in the air gap.Deceased.Translated from Khimicheskie Volokna, No. 2, pp. 17–19, March–April, 1993.     

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.     

Resonance in stretching during the process of spinning fibres from solutions of rigid-chain polymers

Conclusions In spinning from sulfuric acid solutions of poly-p-phenylene-1,3,4-oxadiazole and poly-p-phenyleneterephthalamide, the phenomenon of a periodic pulsation in the diameter of the spun monofilament (stretch resonance) is observed. Resonance parameters have been obtained using a series of model channels having different ratios of length to diameter and different forms of the entrance zone as spinnerets.The moment of onset of resonance is determined by the conditions of flow in the channel.The phenomenon of resonance in stretching probably arises because of the action of hydrodynamic resistance forces at the site of contact of the jet with the precipitation bath surface.Translated from Khimicheskie Volokna, No. 2, pp. 29–30, March–April, 1983.     

Special features in spinning fibres from solutions of stiff-chain polymers through an air gap

Conclusions -- The spinning of yarn from sulfuric acid solutions of poly-p-phenylene terephthalamide and poly-p-phenylene-1,3,4-oxadiazole through an air gap at a high stretch ratio is unstable because of the onset of pulsations in jet diameter, which are stable with time in frequency and amplitude and which is known for polymer melts as stretching resonance. Resonance parameters have been obtained in the use of a series of model channels as spinnerets, where these had various ratios of length to diameter and various forms of the entry zone.-- The onset of resonance depends on conditions for the flow of the polymer solutions in the spinneret channel and on the lengthwise temperature gradient in the air gap.Translated from Khimicheskie Volokna, No. 1, pp. 32–34, January–February, 1991.     

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.     

Analysis of the reasons for the lack of agreement between the results of experimental and theoretical studies of yarn stretching resonance

Conclusions A difference between experimental and theoretical data in the stretching resonance of yarns from a polycaproamide melt has been noted; it indicates a need to take into account dependence of elastic properties of polymers of spinning conditions in modeling this phenomenon.One of the possible approaches which permit one to eliminate disagreements in qualitative and quantitative character of the results from theoretical calculations and from experimental data has been suggested.Translated from Khimicheskie Volokna, No. 2, pp. 9–10, March–April, 1988.     

Method of determining the rheological characteristics of polymers during spinning

Conclusions A method has been proposed for determining rheological characteristics which makes it possible, on the basis of the experimentally measured polymer jet profile and a mathematical model of the spinning process, to estimate rheological parameters which yield difficulty to direct measurement.It has been shown that ambiguity in determination of the viscous and elastic components of jet deformation can be eliminated by using additional experimental data on tensional force or on jet kinematics, determined for other spinning conditions.Translated from Khimicheskie Volokna, No. 2, pp. 7–9, March–April, 1988.     

Modeling processes of the high-speed spinning of viscoelastic polymer melts allowing for the total force balance

Conclusions -- An effective procedure has been proposed for modeling the process of high-speed spinning of viscoelastic polymer melts, which permits one to correctly and rather simply take into account the forces acting on the polymer jet.-- The contribution of forces from aerodynamic resistance, inertia, and gravity to the total force balance has been evaluated. The character of jet deformation in high-speed spinning has been examined and possibilities for regulating it by changing technological parameters have been indicated.Translated from Khimicheskie Volokna, No. 6, pp. 21–23, November–December, 1990.     

A mathematical model of a nonstationary process of fibre spinning from polymer melts

Conclusions The nonstationary problem of fibre spinning from thermoplastic polymers has been formulated and realized on a computer.Solution of the problem makes it possible to model correctly not only the phenomenon of stretching resonance, but also the effect of technological disturbances on spinning instability.Translated from Khimicheskie Volokna, No. 4, pp. 45–47, July–August, 1986.     

Effect of stretching conditions on the properties of cuprammonium fibres spun into aqueous-organic baths

Conclusions The effects of jet stretch, stretching in air, and stretching in a plasticizing bath medium on the physicomechanical properties of cuprammonium fibres spun into aqueous-organic systems have been investigated.The roles of jet stretch and orientation stretch have been demonstrated, and conditions for carrying out these operations have been refined.Translated from Khimicheskie Volokna, No. 5, pp. 20–22, September–October, 1984.     

Effect of spinning conditions on the properties of profiled yarns prepared by the aerodynamic method

Conclusions The effect of spinning conditions on the physicomechanical properties of freshly-spun profiled yarns prepared from polymer melts by the aerodynamic method has been investigated.Physicomechanical properties of profiled and round yarns have been compared.It has been found that the strength of profiled yarns of three-sided, four-sided, or six-sided cross-section is attained at the least stresses. This guarantess more stable spinning and stretching conditions as compared with yarns having other forms of profile.Translated from Khimicheskie Volokna, No. 6, pp. 36–38, November–December, 1985.     

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.     

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.     

Dynamics and kinematics of the process of spinning man-made fibres by the wet method

Conclusions The change in yarn tension has been calculated theoretically as a function of the precipitant concentration in the precipitation bath. For the investigated system (polyoxadiazole), the calculated range in change of tension on transition from mild to severe spinning conditions is 0.45×10^–4<F<0.58×10^–3 N (under conditions of constant rate of take-up).It has been shown that under severe spinning regimes the assigned rate of take-up is attained immediately on exit from the spinneret channel.The effect of yarn tension on expansion (compression) of the polymer jet after exit from the channel has been qualitatively investigated. For polyoxadiazole, the coefficient of jet expansion (compression) varies within the range 0.53<B*<1.77, depending on F.Translated from Khimicheskie Volokna, No. 2, pp. 17–19, March–April, 1989.     

A study of nonuniformity in polyacrylonitrile yarns

Conclusions Nonuniformity of elementary filaments in the spinning of polyacrylonitrile yarns has been studied. It has been shown that the spinning conditions (spinneret hole diameter, concentration and temperature of the precipitation bath) have only a slight effect on the nonuniformity of elementary filaments.Nonuniformity rises along the course of the technological process.The suggestion has been made that the increase in nonuniformity of elementary filaments with respect to diameter is connected with structural nonuniformity in the freshly spun fibres and with the presence of gel particles in the spinning solutions, which lead to an increase in nonuniformity during stretching.Translated from Khimicheskie Volokna, No. 1, pp. 38–39, January–February, 1990.     

Structure formation in high-speed spinning of polyethylene terephthalate

Conclusions Commonness and differences in yarn structure formation by high-temperature and low-temperature stretching have been shown.Model concepts on the development of structure in high-temperature deformation during the process of high-speed yarn spinning have been examined.It has been found that, on changing the linear density of elementary filaments, the spinning speed, or the position of the lubricating device, the proportion of effective high-temperature and low-temperature deformations changes.Translated from Khimicheskie Volokna, No. 3, pp. 16–19, May–June, 1988.     

High-speed spinning of polyester yarns

Conclusions An estimate of the mean lengthwise velocity gradient has been made at 3000 and 4500 m/min); this rises with increase in velocity and degree of stretch, and also as the elementary filaments become thinner.The effect of yarn stretching conditions on change in yarn orientation has been shown for 7, 15, and 25 tex yarns in high-speed spinning.Translated from Khimicheskie Volokna, No. 5, pp. 27–28, September–October, 1985.     

Special features in spinning fine viscose textile yarns

Conclusions Conditions which assure stability of the process of spinning a complex viscose yarn with an increased number of elementary filaments have been determined.It has been shown that stability of the process of spinning complex viscose textile yarn of 13.3 tex linear density with an increase in number of elementary filaments (>60) is increased on reducing the jet stretch, reducing the diameter of the spinneret holes from 0.09 to 0.06–0.05 mm, and bringing the distance between them from 1.4 to 0.5 mm.Translated from Khimicheskie Volokna, No. 3, pp. 39–40, May–June, 1984.     

Cooling yarns spun from polymer melts

Conclusions -- The effect of the component air streams on yarn uniformity with respect to linear density has been established. This has afforded opportunity to find an optimum regime for yarn cooling in spinning from polymer melts. Analysis of the pulsations in air streams has made it possible to determine the basic sources for their origin and ways to reduce them.-- A manufacturing control of the yarn cooling regime using anemometers has been proposed.-- A way of intensifying the yarn cooling regime using an air jet on the yarn section after its initial hardening has been described.-- It is recommended to use the method of investigating the process of yarn spinning by analysis of the component air streams in preparing fibres from polymer melts on any type of spinning equipment.Translated from Khimicheskie Volokna, No. 4, pp. 26–30, July–August, 1990.