Mechanism and kinetics of shrinking of texturized composite fibres having a matrix-fibrillar structure

Conclusions The mechanism and kinetics of shrinkage of complex texturized composite yarns having a matrix-fibrillar structure, and also of yarn shrinkage in a crimp, have been studied.It has been shown that the behavior of a yarn in a crimp on heating, and also the shrinkage of complex texturized yarns, depends considerably on the disposition of the polyethylene fibrils in the polycaproamide matrix.Spinning yarns with a nonuniform disposition of fibrils in the matrix permits one to obtain texturized yarns with a combined spatial-planar twist and an elevated bulkiness.Translated from Khimicheskie Volokna, No. 3, pp. 32–34, May–June, 1988.     

Conditionality of fatigue properties of polyester yarn on physical structure parameters of the polymer

Conclusions An interconnection has been found between the conformational composition of the polyethylene terephthalate structure and fatigue properties in specimens of technical polyester yarn.It has been shown that heat-treatment with an assigned shrinkage of about 14% permits one to increase the resistance of a yarn to double bending by a factor of 2 to 2.5.Translated from Khimicheskie Volokna, No. 3, pp. 42–43, May–June, 1988.     

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.     

Effect of intensive drying of viscose fibres on their properties

Conclusions Experimental data are given on the effect of moisture evaporation rate in drying viscose yarns on the strength and elongation, sorptive capacity for water vapor from the air, swelling, shrinkage, and wear resistance of yarns.It has been found that, by regulating the drying temperature, it is possible to affect the capillary-porous structure of a yarn to a considerable degree. Raising the temperature and the drying rate leads to an improvement in wear resistance and yarn elasticity. However, due to the decrease in internal surface area, one may expect a decrease in the sorptive capacity of the yarn in dyeing. A decrease in drying temperature helps increase the degree of swelling, and helps improve the absorption of dye by the yarn.Translated from Khimicheskie Volokna, No. 2, pp. 46–47, March–April, 1984.     

Yarn laydown mechanism with additional travel of the yarn guide in reversal sections

Conclusions A yarn laydown mechanism has been proposed which makes it possible to reduce the loads acting on the yarn guide and traveler at the moment of reversal.The yarn laydown device described permits one to obtain a package with improved yarn distribution along its axis as compared with the yarn laydown devices of the MF-600-KSh24 and PN-1000-KS18 machines.Translated from Khimicheskie Volokna, No. 4, pp. 18–20, July–August, 1989.     

A combined process for double-twisting and heat-treating textile grade polyester yarn

Conclusions The use of a technological scheme which combines the processes of twisting and yarn heat-treatment makes it possible to intensify the process of textile grade polyester yarn manufacture as a result of shortening the series of textile-technology steps.The scheme permits one not only to set the twist well, but also to regulate the basic physicomechanical properties of the yarns over a wide range.By using the proposed technological scheme, depending on the assigned degree of deformation, one can obtained twisted yarns with a shrinkage of 1–2% at an initial elastic modulus up to 20 MPa.Translated from Khimicheskie Volokna, No. 6, pp. 32–33, November–December, 1984.     

A study of the properties of Oksalon fibre

Conclusions The use of one of the methods of mathematical statistics has made it possible not only to obtain a theoretical formula for the distribution of fibre length in a yarn and to find the connection between the theoretical distribution law and the practical results, but has afforded the possibility of predicting the properties of the final product — the yarn.Fibre processing has confirmed the assumptions stated above on the satisfactory ability of Oksalon fibre to be processed into a high-quality yarn.Translated from Khimicheskie Volokna, No. 5, pp. 37–38, September–October, 1984.     

Change in properties of polycaproamide textile yarns on water-stabilization treatment

Conclusions The kinetics of washout of low-molecular-weight fractions from polycaproamide textile yarns during water-stabilization treatments has been studied. It has been found that the supermolecular structure of the yarns is considerably changed thereupon; the degree of crystallinity is increased, the size of the amorphous regions is reduced, the yarn porosity is increased, thereby increasing the rate of dye sorption, the yarn stress is reduced, and its shrinkage is lowered.The increase in yarn porosity as a result of water-extraction and stabilization treatment ensures raising their sorptive power with respect to dyes and various low-molecular-weight modifiers.Translated from Khimicheskie Volokna, No. 4, pp. 42–44, July–August, 1984.     

Use of cloth from synthetic fibres to clean up (filter) epoxy resins

Conclusions In the filtration of technological solutions of epoxy resins, one can use cloths based on polyamide, polyester, or polypropylene complex yarn, having 290–420 open (interfilament) pores per cm² and through porosity of 5–22%; these have a low hydraulic resistance and permit one to attain the best filtrate quality. They can successfully replace the types of cloths from natural fibres which are being used at present.It is advisable to carry out laboratory evaluation of the suitability of cloths for filtering epoxy resin solutions from the figures for their shrinkage and loss of strength under the action of the solution being filtered; these should not exceed 5–7 and 15–20%, respectively.Translated from Khimicheskie Volokna, No. 4, pp. 48–49, July–August, 1987.     

Effect of the moisture content of viscose textile yarns on their twist uniformity

Conclusions To obtain viscose textile yarns with a maximum twist uniformity, it is advisable to carry out the twisting operation at a yarn moisture content equal to or greater than 10–12% by wt.Raising the moisture content of a yarn to 17% only slightly affects twist uniformity.Reducing the linear density of the elementary filaments raises the twist uniformity of a viscose complex yarn.Translated from Khimicheskie Volokna, No. 2, pp. 40–41, March–April, 1984.     

Mechanism of the development of nonuniformity in properties of yarn prepared by the centrifugal method

Conclusions A mechanism for the generation of nonuniformity in properties of viscose yarn prepared by the centrifugal method by cake layers has been examined.A decrease in yarn nonuniformity, particularly an increase in dyeing uniformity, can be attained by reducing the degree of overall shrinkage of the yarn, by heat treatment of the yarn before its arrival at the centrifuge, or by various methods which lead to a decrease in the volume of the cake: change in degree of yarn swelling, or by drying the cake from inside out.Translated from Khimicheskie Volokna, No. 1, pp. 35–36, January–February, 1987.     

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.     

Increasing the uniformity of viscose textile yarn properties by changing the drying regime

Conclusions An effect of the drying regime on the uniformity of viscose textile yarn properties has been found.Yarns from the outer and inner layers of a cake which has been dried by the from outside in method have differences in strength, elongation, swelling in water, and shrinkage in alkali which are twice as small as yarn which has been dried by the usual method. Uniformity of dyeing of such yarn, which is characterized by the coefficient of variation in the reflective index, is four times as large.Translsted from Khimicheskie Volokna, No. 3, pp. 40–41, May–June, 1984.     

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.     

The reasons for the low extensibility of carpet yarn in the lower layers of packages

Conclusions The reasons for the reduced extensibility of texturized Kapron carpet yarn in the lower winding layers on a package on an AFS-1000 KZh 18 machine have been analyzed.Methods of winding yarn onto packages have been recommended which permit one to reduce scrap formation due to low yarn extensibility in the lower winding layers.Translated from Khimicheskie Volokna, No. 2, pp. 43–45, March–April, 1986.     

Determination of the temperature of a moving yarn

Conclusions A mathematical model has been proposed for the process of heat-exchange between yarn and heating chamber which permits one, with reasonable accuracy, to describe the yarn temperature distribution over the length of the heater and beyond its limits. This model affords the possibility of calculating the amount of heat carried off by the yarn from the heating chamber and to estimate heat losses into the environment, and, consequently, to select the most economical heater.By connecting up the dynamics of yarn heating with yarn properties, the mathematical model developed permits one to calculate the optimum temperature profile in a heating chamber. Using this model, one can transfer the optimum conditions for heat-stretching yarns to other temperature-time levels.Translated from Khimicheskie Volokna, No. 2, pp. 54–56, March–April, 1989.     

Determination of the local coefficient of elementary filament-strength utilization in a complex yarn (or bundle)

Conclusions -- A procedure has been proposed for determining the local coefficient of elementary-filament strength utilization in a complex yarn.-- The procedure permits one from a one-time test of a yarn to find the coefficient of strength utilization in an investigated small section of the yarn (the local K_ut).-- The proposed procedure is recommended for determining the local K_ut in any section of an investigated yarn with a minimum labor expenditure.St. Petersburg Institute of Textile and Light Industry. Translated from Khimicheskie Volokna, No. 5, pp. 43–46, September–October, 1992.     

Control of the process of spinning complex yarns from points of light reflection

Conclusions Points of light reflection are observed when a spun yarn is illuminated with a point light source in the sweeping zone.From the height and form of the zone for the position of points of light reflection, one can measure the nonuniformity in diameters of the elementary filaments in a section of complex yarn, work out an optimum regime for cooling the spun yarn, and monitor clogging of spinneret holes directly in operation.Translated from Khimicheskie Volokna, No. 6, pp. 53–55, November–December, 1987.     

Mathematical model of the fibre laydown mechanism with a single-channel helical reel and reversing yarn guide

Conclusions The mathematical model examined permits one to do the following: perform a complex study of the high-speed yarn laydown mechanism; determine the kinematic and dynamic parameters of the mechanism; determine the optimum geometric dimensions of the yarn guide.Translated from Khimicheskie Volokna, No. 3, pp. 11–13, May–June, 1989.     

Spinning viscose textile yarn into a zinc-aluminum-containing precipitation bath under manufacturing conditions

Conclusions Viscose textile yarn has been prepared by spinning in a zinc-aluminum-containing precipitation bath under manufacturing conditions.The yarn-spinning process in a zinc-aluminum-containing bath is stable, and is accompanied by an increased evolution of carbon disulfide and hydrogen sulfide.Viscose textile yarn spun in a zinc-aluminum-containing bath conforms to the All-Union State Standard and is characterized by a lower elongation and an increased swelling and shrinkage.Processes of warping and weaving the yarn have been carried out without any difficulties.O. M. Savchenko, senior engineer of the Klinsk Khimvolokno Industrial Association, also took part in this work.Translated from Khimicheskie Volokna, No. 6, pp. 34–35, November–December, 1988.