Spinning disk mechanism of a machine for spinning aramid fibres

Altering the design of the spinning disk mechanism used in spinning aramid fibres will increase the lifetime of the mechanisms and the quality of the spun fibres. Translated from Khimicheskie Volokna, No. 5, pp. 55–56, September–October, 2008.     

Variants of use of the modified Lindsley-Leont'eva method for chemical fibre spinning products

The mechanical instrument developed by I. S. Leont'eva for assessing the structural properties of products of cotton spinning by the Lindsley method can be used without structural changes with different methods for yarn made of chemical fibres with an average length in the ranges of 32–42, 57–107, and 124 mm. The use of the instrument and its modifications for correctly evaluating the structural products of products of spinning by the Lindsley method for the entire possible range of fibre lengths requires creating a base of the corresponding values of the fractional coefficients. The solution of these problems corresponds to the requirements of the manufacturers and consumers of chemical fibres for the length of staple fibres and the filament stapling length in expanding the yarn assortment. Moscow State Textile Academy. Translated fromKhimicheskie Volokna, No. 4, pp. 52–54, July–August, 1999.     

Some parameters of spinning poly-p-phenylene terephthalamide fibres through an air gap

The spinneret draw ratio for jets of LC solutions of PPTA (range of 1 to 10) is a basic parameter in spinning of high-strength fibres through an air gap. The strength of the fibres is a function of the conditions of intense spinneret drawing of the jets of LC solutions of PPTA and the spinning speed. Most of the sulfuric acid (solvent) passes into the spinning bath as a result of brief contact of the jet of LC PPTA solution and fibres with it during spinning. Translated from Khimicheskie Volokna, No. 2, pp. 12–14, March–April, 1998.     

Regulation of the structure of fibres from polymer solutions

The properties of fibres “wet” spun from solutions of polymers can be altered within wide limits by using information on the rheological properties of the spinning solutions, the phase equilibrium diagrams of polymer—solvent—precipitator systems, and information on the glass transition and crystallization in the system. The homogeneity of the structure and properties of the fibre increase in the order of spinning methods: diffusion, thermotropic, mechanotropic. __________ Translated from Khimicheskie Volokna, No. 4, Pp. 10–17, July–August, 2006.     

Rheological properties of liquid-crystalline solutions of poly(p-phenylene terephthalamide) and behavior of the jet in spinning through an air space

LC solutions of PPTA behave like liquids with a power law of flow and n =0.65–0.78 for flow through the channels of standard spinnerets with small diameters and q =0.88–0.95 for longitudinal flow in jets. Spinneret expansion of a freely falling jet in channels with small diameters is equal to 1.70–1.75 and is not a function of the shear rate on the wall. Spinneret expansion is preserved in conditions of repeated drawing of the jets in the air space until very small air spaces at 1.5–2.5 mm are used. In spinning PPTA fibres through an air space with a high jet draw ratio, only a small fraction of this drawing in the spinning bath is possible. Translated from Khimicheskie Volokna, No. 2, pp. 3–7, March–April, 1997.     

Automatic control system for spinning and winding of synthetic fibres

An automatic control system for spinning and winding of synthetic fibres that provides for operation of the electric drive of the metering pumps in conditions of stabilization of the melt pressure and rotation rate of the winder drive was proposed. A laboratory bench that simulates operation of the device for controlling spinning and winding of synthetic fibres based on software provided in a microcomputer was created. A parametric, adjustable, asynchronous electric drive from the KPE series which provides for energy-saving conditions was used for the extruder drive. __________ Translated from Khimicheskie Volokna, No. 3, pp. 56–57, May–June, 2007.     

Gelation mechanisms in spinning of fibres from solutions of polymers

Gelation mechanisms in spinning of fibres from solutions of polymers are discussed: diffusion, thermotropic, mechanotropic. The characteristic gelation times by the different mechanisms were estimated. The effect of the gelation mechanisms on the properties of the gel and fibres was examined. Tver' Technical University; All-Russian Scientific-Research Institute of Synthetic Fibres, Tver'. Translated fromKhimicheskie Volokna, No. 2, pp. 27–29, March–April, 2000.     

Structural and chemical transformations in thermooxidative stabilization of copolymeric polyacrylonitrile fibres

The processes that take place during thermooxidative stabilization in copolymeric polyacrylonitrile (PAN) fibres of varying composition were examined. It was shown that the primary, or relaxation, shrinkage of PAN fibres is a function of the conditions of their fabrication and can be reduced by annealing the fibres above the glass transition temperature. The chemical transformations of PAN fibres are accompanied by structural transformations, manifested as shrinkage or elongation (flow) of the fibre. Mechanisms of deformation processes are proposed. The schemes of the chemical transformations of the structure of the fibres during their thermooxidative stabilization were examined. The direction and rate of chemical transformations of the structure of the fibres are a function of the composition of the copolymers; these parameters can be assigned and regulated by altering the conditions of spinning the fibres in the spinning bath. All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated fromKhimicheskie Volokna, No. 6, pp. 14–18, November–December, 1999.     

Wet spinning of acrylic microfibres

Polyacrylonitrile microfibres with a linear density of 0.02–0.10 tex can be manufactured by wet spinning into spinning baths with a low concentration of precipitant. When the jets of spinning solution come into contact with such a spinning bath, a concentration of precipitant lower than the threshold concentration where coagulation does not take place is established on the surface of the fibre for a short time (0.02–0.56 sec). The spun fibres have a liquid segment longer than the stressed part of the jet exposed to normal stresses. Fibres with a liquid segment can be drawn by 5–10 times, which allows fabricating microfibres with a linear density of 0.02–0.10 tex having a strength of 45–80 cN/tex and elongation of 15–20%. Fibres spun into baths with a low concentration of precipitant have high porosity, which could be attributed to formation of a liquid polymer phase in phase decomposition of the spinning solution. All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated fromKhimicheskie Volokna, No. 3, pp. 16–20, May–June, 2000     

New chemical fibres and yarn for upholstery and industrial fabrics

A new assortment of fabrics was developed using air-textured, shaped fibres and yarn with the aerodynamic method of spinning. The use of these fibres and yarns will reduce the cost and specific material consumption for woven and knit articles. Vitebsk State Technological University, Belorussiya. Translated fromKhimicheskie Volokna, No. 2, pp. 22–23, March–April, 1999.     

Nanotechnologies and chemical fibres

The features of nanotechnologies and possibility of applying them in research and industrial practice in the chemical fibres sector are examined. Structural elements 1–100 nm in size are the objects of nanotechnologies. The cross sections of fibrils and their crystalline sections (large periods) whose structure determines the mechanical and physical properties of the fibres fall in this range. In the initial stage, the chemical fibres were improved, especially with respect to increasing the strength, by orientation drawing, which corresponded to the nanotechnology principle of “top-down” processing. The wide use of the more progressive “bottom-up” processing principle by regulating the fibrillar structure by selecting the optimum conditions of spinning the fibre was recently supplemented by the method of self-ordering on the molecular level through the liquid-crystalline state. Fibre strength of 500–600 kgf/mm² was attained with this method. The energetic mechanism of transition of a substance into the liquid-crystalline state was substantiated. To attain a high degree of ordering of the fibrils before spinning, it is necessary to destroy the structural network of linkages in the spinning solutions and melts as completely as possible. __________ Translated from Khimicheskie Volokna, No. 1, pp. 26–30, January–February, 2008.     

Degradation Processes in Production of Vidlon Polycaproamide Cord Thread

In spinning fibres on type PP-1000 IM machines, complex changes take place in polycaproamide, caused by the occurrence of thermal oxidation and thermal degradation processes. The content of carbonyl compounds increases with an increase in the temperature and draw ratio of the fibres in the polymer. Thermal degradation processes decrease with an increase in the drawing temperature. __________ Translated from Khimicheskie Volokna, No. 4, pp. 39–41, July–August, 2005.     

Stability boundaries for spinning of fibres based on poly-p-phenylene terephthalamide through an air gap

The restriction of the zone of stationary jet flow of LC sulfuric-acid solutions of PPTA and the conditions of stable spinning of fibres with small air gaps using spinnerets with small-diameter channels is explained with the well-known theory of resonance in drawing for viscoelastic, non-Newtonian media in continuation of the effect of shear flow in the channels on longitudinal flow in the jets. In spinning fibres from 19.5% LC sulfuric acid solutions of PPTA and copolyamide, drawing of the jet in the spinning bath supplements drawing of the jet in the air gap. The former is slight and is a function of the stress created in deformation of the LC solution in the air gap, area of the jet cross-section on the surface of the spinning bath, and type of polymer. The conditions of extreme spinning regimes with breaks in PPTA and polyamide monofilaments in the spinning bath medium in the absence of resonance in drawing of the jet in an air gap are presented. Terlon Co., Mytishchi. Translated fromKhimicheskie Volokna, No. 1, pp. 12–16, January–February, 1999.     

New trends in increasing the quality of para-aramid fibres from domestic manufacturers

Changing the design of metering pumps used in spinning allows increasing the quality of para-aramid fibres. When the cast-iron body of the pumps is replaced by a body made of a composite material with a polymer matrix, the amount of gas bubbles formed in electrochemical and chemical reactions in friction pairs and in pump channels decreases. __________ Translated from Khimicheskie Volokna, No. 1, pp. 21–23, January–February, 2006.     

Effect of the structure of textile materials on modification of cotton fibres in treatment with sodium hydroxide solutions

It was found that the structure of cotton fabrics restricts swelling of the fibres required for spinning alkaline cellulose and polymorphous conversion of the polymer in treatment with sodium hydroxide solutions. The necessity of individually selecting the concentration conditions of mercerization for fabrics of different structure for the optimum treatment time of 20 sec was demonstrated. __________ Translated from Khimicheskie Volokna, No. 5, pp. 31–34, September–October, 2007.     

High-speed spinning and orientational strengthening of polyester fibres. Analysis and prospects for development. A review

The processes are classified and the theoretical and technological premises for substantiation of orientational strengthening schemes are examined. Modern technological schemes for separate and combined processes of high-speed spinning and orientational strengthening are described, and the prospects for development of new technologies are evaluated. The evolution of orientational strengthening technology is based on multistage drawing for obtaining high-strength fibres and one-stage processes for obtaining medium-strength fibres. Examples of the implementation of modern schemes for production of polyester fibres are reported. Translated from Khimicheskie Volokna, No. 6, pp. 7–13. November–December, 1997.     

Polymer composite materials based on modified synthetic fibres

The possibility of fabricating polymer composite materials (PCM) based on modified PCA and PP fibres was demonstrated. The kinetic features of curing of epoxy oligomer in the presence of profiled PCA and PP fibres were investigated. The optimum technological regime of spinning of PCM was selected using the method of the full factorial experiment. A series of samples of PCM based on profiled fibres was prepared and their properties were comparatively evaluated. Translated from Khimicheskie Volokna, No. 1, pp. 45–48, January–February, 1997.     

Status and prospects for development of polyester fibre and yarn production technology

Current production schemes for polyester fibres and textile and industrial yarn and the prospects for development of their production technology are examined. Changing to economical direct melt spinning processes and to use highly efficient units for separate and combined spinning-drawing of fibres and yarn spun from melt and granulate, increasing textile fibre spinning and texturing speeds, and introducing continuous process and product quality control systems are the main trends in the evolution of modern plants. Most of the attention is being focused on creating flexible process lines that make it possible to raise the quality, rapidly change the assortment, and manufacture products that satisfy market requirements. __________ Translated from Khimicheskie Volokna, No. 4, pp. 28–39, July–August, 2006.     

Effect of the conditions of spinning viscose textile fibres on their properties

Rigorous respect of the standard character and purity of the spinning solution, spinning bath parameters, and orientation draw ratio ensures obtaining a complex fibre homogeneous over the length. By varying the flow rate of viscose from the spinneret and disk rotation, it is possible to vary the fibre tension, strength, elongation, and shrinkage within wide limits and ensure a high capacity for uniform dyeing. The limits of the overall draw ratio of viscose textile fibres of varying assortment without elementary fibre breakage and formation of nap were established. __________ Translated from Khimicheskie Volokna, No. 6, pp. 28–31, November–December, 2005.