Heat exchange in the stretch roll-yarn system in stretching complex synthetic yarns

Conclusions At assigned values of the technological process of yarn stretching (speed, temperature, stretch ratio, and number of turns), both the temperature of the lower stretch roll and also the time of departure into a steady temperature regime are unambiguously determined.High yarn breakage at the start of operating time for output on twisting and stretching machines may be explained by an insufficient surface temperature of the lower stretch roll.The temperature of the lower stretch roll surface reaches a steady value after approximately 600 sec (depending on the temperature and rate of fibre movement). The yarn produced during this time has reduced physico-mechanical properties.To improve the passage of yarns which are drawn on twisting and stretching machines, it is advisable to make the lower stretch rolls heatable at the initial moment of operation, and also to reduce their weight.Translated from Khimicheskie Volokna, No. 6, pp. 18–20, November–December, 1986.     

Heating of synthetic yarns during the process of stretching and heat-setting

Conclusions It has been proposed to determine the mean yarn temperature in the cold stretching zone, and also the power which it is necessary to supply to the yarn from the stretching mechanism side, from stretching process technological data.The coefficients of friction of polyamide and polyester complex yarns on pyroceram rolls and stretch cylinders have been determined experimentally.Translated from Khimicheskie Volokna, No. 3, pp. 44–46, May–June, 1987.     

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.     

Results of studying yarn tension on type PN-1000-KS18 two-yarn machines

Conclusions Tension force depends on the adhesion of the freshly spun fibres with the surfaces of the spinning rolls, and is determined as a function of the linear density of the yarn, the composition of the lubricant preparation, the diameter of the spinning rolls, the trajectory of the yarn movements, and the angle encompassed on the spinning rolls by the yarn. These parameters are the starting points for designing machines for the take-up and winding of freshly spun yarns and should be reflected in customer requirements.Replacement of the upper spinning roll by a roll with a cylindrical surface for yarn A and a conical surface for yarn B at an appropriate conicity, and also upon use of lower spinning rolls of identical diameter makes it possible to regulate the yarns B tension in a range which is adequate for equalizing tension within allowable limits for yarns of various assortments.The operation of positions in the twisting and stretching machine and slippage of yarn with respect to the rolls may be judged from the linear density of the freshly-spun and drawn yarn.Determination of the state of working units of the take-up and winding machine is possible from tension measurements.Translated from Khimicheskie Volokna, No. 5, pp. 53–55, September–October, 1989.     

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.     

Mechanism of fibril extension in a deformable composite yarn of the “matrix-fibril” type

Conclusions For composite yarns of the matrix-fibril structure, the fibril distribution which is attained in the stretching process with respect to stretch ratio (and correspondingly with respect to mean degree of molecular orientation) is brought about the original fibril distribution by size (diameter and length).In the orientation stretching of a composite yarn, the stretching of fibrils takes place with a stretch ratio equal to or less than the stretch ratio of the matrix.Translated from Khimicheskie Volokna, No. 2, pp. 3–5, March–April, 1989.     

Use of ceramic coatings for yarn guides in equipment for processing man-made fibres

Conclusions Diamond smoothing of ground parts which have been coated with a ceramic considerably changes the microtopography of the surface and increases the contacting ability of the surface of the parts with the yarn as compared with diamond polishing.The entire surface of the yarn-guiding fitting allows yarn slippage, the maximum slippage rate for a definite angle of inclusion by the yarn being constant, and it depends on the state of the microtopography and the material of the surface.With the objection of reducing the slippage coefficient in using rolls coated with a ceramic, one should use the largest possible rate of yarn delivery.Translated from Khimicheskie Volokna, No. 5, pp. 58–59, September–October, 1989.     

Effect of stretching conditions on the properties of polyester textile yarns

Conclusions By varying the temperature of the heating roll and, correspondingly, the magnitude of the natural stretch ratio, one can obtain a required level of change in shrinkage in a definite sequence; and by periodicity of removal of the yarn being stretched from the heater, one may obtain lengthwise variation in shrinkage of polyester textile yarn.Translated from Khimicheskie Volokna, No. 2, pp. 37–39, March–April, 1987.     

Some special features in texturizing complex Karbimid yarns

Conclusions The effect of the orientation stretch ratio of complex Karbimid yarns on their physicomechanical properties has been examined.It has been found that, to increase the ability of complex Karbimid yarns to undergo texturizing, it is advisable to use a yarn with a degree of orientation stretch of 600%.Translated from Khimicheskie Volokna, No. 1, pp. 32–33, January–February, 1984.     

High-speed stretching of polyamide textile yarns

Conclusions Studies of the process of drawing 5-tex polyamide textile yarn at take-up speeds up to 1650 m/min have been performed on a laboratory stand.It has been found that, with increase in stretching speed, within the investigated limits the drawing force and physicochemical properties of the yarn essentially do not change. This permits us to recommend an increase in stretching speed for industrial adoption.Translated from Khimicheskie Volokna, No. 1, pp. 22–24, January–February, 1986.     

Effect of length of a complex yarn on its mechanism of failure in extension

Conclusions A quantitative characterization of nonsimultaneity in failure of the elementary filaments in a complex yarn on the right-hand part of the stretching diagram has been given.Some features of the failure of elementary filaments in a complex yarn at various sample clamped lengths have been examined.A method has been proposed for evaluating nonuniformity in breaking characteristics of elementary filaments in a complex yarn from the right-hand part of the stretching diagram at a low clamped length, and also from the ratio of the works of deformation to maximum loading and to complete yarn failure.Translated from Khimicheskie Volokna, No. 3, pp. 52–53, May–June, 1989.     

Effect of diameter nonuniformity in unoriented monofilament on stretch ratio and strength of the final fibre

Conclusions Dependences have been obtained which make it possible, for the stretching scheme examined, to carry out a comparison with a monofilament which is uniform in diameter, with respect to limiting stretch ratio and strength after stretching, at any character of change in diameter of an undrawn filament.It has been shown that the stretch ratio and the strength of a drawn monofilament are determined by the ratio of the maximum diameter to the minimum diameter (D/d), and also by the character of the change in diameter over the length of the undrawn monofilament.Translated from Khimicheskie Volokna, No. 6, pp. 11–12, November–December, 1987.     

Structure and properties of dyed polypropylene yarn containing an addition of chemically colored low-molecular polycaproamide

Conclusions The thermal properties of PP yarns have been studied by determining their weight loss on heating. It has been shown that, by comparison with unmodified PP yarn, yarns containing an addition of chemically dyed LMPCA have improved thermal stability.Addition of chemically dyed LMPCA in the spinning of PP yarn leads to an increase in mean crystallinity and a decrease in the average size of yarn crystallites after jet stretch. The existence of two morphological forms of supermolecular structure has been shown by the electron microscopy method: spherulitic and oriented along the yarn axis.Translated from Khimicheskie Volokna, No. 6, pp. 20–21, November–December, 1986.     

The ratio of the travelling speeds of the coagulating bath and the filament in vertical tubes on continuous machines

Conclusions 1. Analysis of the experimental and calculated results shows that to make a good quality cord yarn, and for regular running of the process during spinning with negative spinneret stretching, the coagulating bath should have a speed somewhat lower than that of the yarn being spun. In this case the flow of the liquid creates the most favourable conditions for spinning the yarn.2. The optimum ratios of the yarn and coagulating bath speeds depend both on the process parameters (inverse dependency on the amount of spinneret stretch), and also on the configuration of the spinning tube.Moscow Textile Institute. Translated from Khimicheskie Volokna, No. 5, pp. 25–26, September–October, 1969.     

Raising the quality of technical yarn by improving the state of KV-III-250KA twisting and stretching machines

Conclusions As a result of improving the technical state of the KV-III-250KA machine, a stabilization in the physicomechanical properties of polycaproamide tire cord yarn has been achieved.Installation of lower stretch rolls with a gas-plasma sprayed hard alloy coating on the KV-III-250KA machines makes it possible to considerably raise the quality level of the drawn tire core yarn.Translated from Khimicheskie Volokna, No. 5, pp. 56–57, September–October, 1989.     

An approximate method of evaluating spinning conditions for polycaproamide yarns

Conclusions An approximate criterion has been developed for evaluating technological processes for preparing technical polycaproamide yarns; it is based on analysis of physicomechanical properties.It is advisable to use the proposed method in comparing processes which differ in yarn stretch ratio.Translated from Khimicheskie Volokna, No. 4, pp. 16–17, July–August, 1986.     

Double-strand scheme for spinning technical viscose yarn

Conclusions A two-strand scheme for spinning technical viscose of 183.5 tex linear density has been developed under experimental production conditions. The yarn obtained by this scheme has a breaking load of 38–40 cN/tex at an elongation of 8–10%.In the developed scheme, combination of the processes of orientation stretching, final regeneration, and complete driving off of carbon disulfide from the yarn is provided for, which makes it possible to localize the evolution of harmful gases in the zone of the precipitation and plasticizing baths and to obtain a concentrated gas-air mixture which is suitable for regeneration.Translated from Khimizheskie Volokna, No. 1, pp. 31–33, January–February, 1988.     

A device for the take-up of pneumatically tangled acetate yarns onto a spinning package

Conclusions Three variants of take-up and winding devices have been developed; these permit one to take up yarn from the spinning machine onto a commercial package by a frictionless method and ensure a constant linear velocity of yarn winding.The device operates under the following regimes: linear winding rate, 400–600 m/min; yarn tension up to regulating roll, 4.5–5.0; tension after it, 8–9 cN; weight of package, 3 kg.The devices ensure obtaining acetate pneumatically tangled yarns with 15–35 pneumatically tangled sections per m of yarn with a uniform distribution over the yarn length; the density of the yarn in the package is 850–950 kg/m³.Translated from Khimicheskie Volokna, No. 1, pp. 46–48, January–February, 1985.     

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.     

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.