Properties of yarns spun from a cellulose triacetate melt

Conclusions The physicochemical and physicomechanical properties of yarns spun from a cellulose triacetate melt have been studied.It has been shown that in physicomechanical properties CTA yarns spun from the melt are identical to yarns spun by the dry method.It has been found that the lower sorptive power and lower shrinkage of yarns from the melt are connected with the special features of their spinning.Translated from Khimicheskie Volokna, No. 5, pp. 23–25, September–October, 1984.     

Radiation resistance of acetate and triacetate yarns

Conclusions The radiation resistance of acetate and triacetate yarns has been studied. It has been shown that, in retention of physico-mechanical properties at a radiation dose of 10 Mrad, the yarns may be placed in the series: acetate, dull > acetate, bright > acetate dyed > triacetate, bright.It has been found that irradiation of acetate yarns with small doses leads to an increase in their resistance to abrasion with practically complete retention of the original strength. The effect of radiative improvement is higher in acetate yarns which have been dulled with titanium dioxide.Translated from Khimicheskie Volokna, No. 3, pp. 31–32, May–June, 1988.     

Orientation processes in acetate yarns under the influence of certain solvent vapors

Conclusions Treatment of acetate yarns with vapors from solvents which form a liquid-crystal phase with the polymer leads to initiation of orientation processes which are accompanied by spontaneous yarn elongation. This makes it possible to prepare yarns of low linear density and with improved physicomechanical properties.It has been found that the action of vapor from nitromethane, which forms a lyotropic, liquid-crystal phase in cellulose acetates, takes place in several stages.A mechanism has been proposed for the interaction of the polymer with vapor from a solvent which forms a liquid-crystal phase with it.Translated from Khimicheskie Volokna, No. 2, pp. 13–15, March–April, 1989.     

Change in structure and properties of polycaproamide on repeated stretching of tire-cord yarns

Conclusions It has proven to be possible to study the structural changes which arise in the polycaproamide cord yarn in fenders during use by the paramagnetic probe (PMP) method. These changes are manifested in the rotational diffusion parameters of the PMP, and in the position and number of temperature transitions.Extended use of articles leads to a decrease in the degree of crystallinity of the polycaproamide and to a decrease in the volume of structural regions having a low segmental mobility. Considerable structural changes arise after 7–8 years use of the fenders.Translated from Khimicheskie Volokna, No. 2, pp. 25–27, March–April, 1988.     

Effect of the degree of polymerization of cellulose triacetate on the physicomechanical properties of yarns

Conclusions The dependence of the relative breaking load and elongation at break of cellulose triacetate yarns and the resistance to abrasion and to repeated bending on specific viscosity of the polymer have been investigated.On increase in specific viscosity from 0.32 to 0.41, the fibre strength rises from 9 to 11.4 cN/tex; the resistance to bending, from 1200 to 2000 cycles; the resistance to abrasion, from 1000 to 8000 cycles. The elongation at break and resistance to repeated stretching change but little with increase in specific viscosity.Translated from Khimicheskie Volokna, No. 3, pp. 46–47, May–June, 1985.     

Change in deformation properties of complex polyamide yarns under conditions of variable atmospheric humidity

Conclusions The change in deformational properties of polyamide yarns during the aging process is explained by a densening of their structure during water vapor sorption-desorption cycles at a variable humidity of the surrounding medium.Under conditions of variable humidity, the elastic component of deformation rises, approaching the analogous figure for heat-treated fibre.Translated from Khimicheskie Volokna, No. 2, pp. 48–49, March–April, 1985.     

Change in the structure and mechanical properties of complex glass fibres during dyring

Stekloplastik—Sertifikat Corporation Moscow. Translated from Khimicheskie Volokna, No. 2, pp. 58–59, March–April, 1994.     

Change in properties of man-made fibres and fabrics made from them under the action of epoxy resins

Conclusions A prolonged action of a toluene solution epoxy resin on polyamide or polyester yarns and fabrics from them causes a change in their geometric characteristics and physico-mechanical properties.This changes are within acceptable limits; therefore textile materials based on the investigated yarns can be used for technological filtration of epoxy resins.Translated from Khimicheskie Volokna, No. 3, pp. 38–39, May–June, 1987.     

Change in mechanical properties,composition, and structure of hydrated polyurethaneurea

Relative to the extensive study on the relationship between the structure and properties of polyurethane (PU) and polyurethaneurea (PUU), basic information available on hydrated PUU is limited. In this study, PUU films were immersed in a saline solution (0.9 wt % NaCl, 37°C) for periods of up to 60 days and evaluated by the change in static and dynamic mechanical properties, composition, and hydrogen‐bonding structure. It was found that immersion in a saline solution could greatly increase the average molecular weight and degree of phase separation, which enhanced the mechanical strength and reduced the flexibility. The increase in the average molecular weight is believed to come from the chain extensions or crosslink reactions between intramolecules and/or between intermolecules and from the leaching out of poly(tetramethylene oxide) (PTMO) oligomers. FTIR analysis indicated that H₂O molecules did not obviously alter the hydrogen‐bonding structure of PUU. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 252–260, 2001     

Effect of the temperature on the structure and mechanical properties of poly(ethylene terephthalate) fibres and yarns

The load—elongation diagrams were obtained for PETP yarns and monofilaments at different deformation temperatures, demonstrating the dependence of the σ(ε) curves on the testing temperature and the thermomechanical history of the samples. The dependences of the basic strain characteristics determined from the σ(ε) curves on the temperature can be used to predict the change in the mechanical properties of PETP yarns and fibres at high temperatures. In addition to the fundamental relaxation transition, the σ(ε) curves can be used to find a new transition in the 180°C region which controls the behavior of PETP yarns and fibres above the transition temperature. The thermomechanical tests and structural studies of the fibres at different temperatures allow correlating the transition found with crystallites and assigning it to an α_c transition based on the characteristic set of properties. St. Petersburg State University of Technology and Design. Translated fromKhimicheskie Volokna, No. 1, pp. 32–35, January–February, 2000.     

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.     

Effect of gamma-irradiation on the mechanical properties of carbon nanotube yarns

Gamma-irradiation of carbon nanotube yarns in air has significantly improved the tensile strength and modulus of the yarns, presumably because of an increased interaction between the individual nanotubes. The improvement has been much greater for tightly structured yarns than for loosely structured yarns. Sonic pulse tests have also shown increased sound velocity and dynamic modulus in the carbon nanotube yarns as a result of gamma-irradiation treatment. X-ray photoelectron spectroscopic analyses on progenitor carbon nanotube forests show that gamma-irradiation treatment in air has dramatically increased the concentration of oxygen, for example as carboxyl groups, in the carbon nanotube assemblies in proportion to radiation dose, indicating that carbon nanotubes were oxidized under the ionizing effect of the gamma-irradiation. Such oxygen species are thought to contribute to the interaction between carbon nanotubes and thus to the improvement of carbon nanotube yarn mechanical properties.     

Estimating the character of the distribution in mechanical properties of technical complex yarns

Conclusions The possibility of approximating the results of strength (breaking load) tests by the normal, logarithmically normal, or Weibull distribution has been shown in the case of technical complex yarns from various methods of preparation, having various levels of defectiveness.The best confirmity of the experimental data to the three-parameter Weibull distribution has been noted.Translated from Khimicheskie Volokna, No. 6, pp. 48–49, November–December, 1986.     

Fabrication and mechanical properties of carbon nanotube yarns spun from ultra-long multi-walled carbon nanotube arrays

Carbon nanotube (CNT) yarns have been fabricated by dry spinning from vertically aligned millimeter-long multi-walled carbon nanotube (MWCNT) arrays and their mechanical properties have been studied. By using 2-mm long CNTs and densely packing of CNT yarns we achieved a tensile strength of 1068 MPa and Young’s modulus of 55 GPa. Our CNT yarns have diameters of tens of micrometers being easy to handle and possessing high effective load capacity up to 0.81 N. We discuss mechanical properties of CNT yarns spun from relatively thick MWCNT along with a detailed analysis of various post-spin processes and their effect on CNT yarns characteristics. Also, we point out the difference between mechanical properties of dry spun CNT yarns and conventional spun textile yarns.     

Change in properties of texturized carbimide yarns on additional heat treatment

Conclusions The heat-setting process in texturizing and supplementary heat-treatment affects the change in physicomechanical and specific properties of low-extensibility carbimide yarns.It is recommended to carry out supplementary heat-treatment of a highly-extensible carbimide yarn at a heating chamber temperature of 120–125°C.Translated from Khimicheskie Volokna, No. 6, pp. 35–36, November–December, 1985.