Porometric and electron-microscope investigation of polycaproamide fibres treated with a glow discharge

Conclusions Morphological changes in polycaproamide fibre which take place on contact with high-frequency glow discharges have been studied.Using the methods of reference and mercury porometry and scanning electron microscopy, it has been found that thereupon the specific surface, density, microrelief, total porosity, pore geometry, and pore distribution by size are significantly changed, the intensity and direction of these processes depending on the composition of the gas in which the modification is taking place and the power characteristics of the discharge.Translated from Khimicheskie Volokna, No. 6, pp. 30–31, November–December, 1988.     

Effect of molecular mobility on the deformation characteristics of polycaproamide fibres

The deformation characteristics of PCA fibres are a function of the deformation temperature to a significant degree. The character of the curves of E(ε), E_max(t), σ_b(t), and ε_b(t) indicate a pronounced change in the mechanical properties of PCA fibres not only in “thawing” of segmental mobility in amorphous regions of the polymer, but also in passage of crystallites into the mesomorphic state, which is characterized by pronounced weakening of interchain interactions in the crystallites. The first segment of σ(ε) is only observed in the curves for PCA fibres in the glassy state. In activation of segmental mobility, the σ(ε) curves only contain the second and third segments. St. Petersburg State University of Technology and Design. Translated fromKhimicheskie Volokna, No. 6, pp. 30–31, November–December, 1999.     

Effect of the type of spinneret on the quality of polycaproamide fibres

It was found that PCA fibres spun on spinnerets with a hyperboloid entry zone are characterized by lower density and higher birefringence. This improves the capacity of the fibres for orientational drawing and makes it possible to increase their physicomechanical indexes. The PCA textile fibres manufactured in the new spinnerets have good specific dyeing characteristics. EAD Ekomedbio Business and Innovation Center, Sofia, Bulgaria. Translated fromKhimicheskie Volokna, No. 5, pp. 27–29, September–October, 1999.     

Effect of electrodeless glow discharge on polymers

The effects of gas plasma generated by electrodeless (inductive coupling) glow discharge on polymers were investigated as functions of gas pressure, discharge power, exposure time, and type of plasma gas. A remarkable similarity between the plasma susceptibilities of low molecular weight organic compounds and polymers was observed; i.e., polymers which have ether, carbonyl, ester, or carboxylic acid attached to a nonaromatic structure are very susceptible to plasma. The weight loss was proportional to the exposure time and exposed area. The discharge power and type of gas were found to have a great influence on both the rate of weight loss and the morphology of the exposed surface. The predominant effect of plasma on polymers was found to be degradation (manifested by weight loss). The crosslinking effect was found to be marginal with many polymers; however, significant crosslinking was observed with double bond-containing polymers. The crosslinking was examined by swelling the treated films. With copolymers of styrene–butadiene, 4-vinylpyridine–butadiene, methacrylic acid-butadiene, and acrylic acid–butadiene, the crosslinking was greatly dependent on the discharge power, the butadiene content of the copolymers, and the exposure time. Both degradation and crosslinking by gas plasma were generally limited to the exposed surface; however, the propagation of crosslinking in the direction of thickness was observed with copolymers of styrene–butadiene. The plasma of organic vapor also cause degradation of plasma-susceptible polymers, particularly at high wattage, although the deposition of polymer occurs simultaneously.     

Effect of spinning conditions on the structure of Vidlon polycaproamide textile fibres

Combined thermal analysis showed that drawn polycaproamide fibres spun in spinnerets whose input zone is in the form of a hyperboloid are characterized by better stability up to total melting in comparison to fibres spun in classic spinnerets. The lower weight loss and higher activation energy of thermal degradation of the fibres evidence of this finding.Translated from Khimicheskie Volokna, No. 5, pp. 37–40, September–October, 2004.     

Effect of DC glow discharge treatment on the surface energy and surface resistivity of thin film of polypropylene

A change in the surface energy and surface resistivity of a thin film of polypropylene (PP) of thickness 100 μm was investigated, using direct current (DC) glow discharge. The thin film of the PP was treated for various discharge powers and treatment time and the modification in the surface energy and the surface resistivity was observed. To investigate the modification in the surface energy after DC glow discharge treatment, contact angle of two test liquids formamide and de‐ionized water over the surface of PP film was measured. By measuring the contact angle the change in surface energy and its two polar and dispersive components have been measured. It was observed that at a given power level of DC glow discharge surface energy and its polar component increases with increase of the treatment time, attains a maximum value, and then becomes almost constant. Correspondingly, with increase in surface energy, a decrease in surface resistivity was observed. Also, a change in surface morphology was observed by atomic force microscopy and by FT‐IR spectra generation of polar groups at the surface of PP film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 767–772, 2007     

Polymerization of organic compounds in an electrodeless glow discharge. XI. Pressure in glow discharge

The pressure of a steady-state flow of monomer, p₀, changes to a new steady-state flow pressure, p_g, in glow discharge. The value of p_g is dependent on the flow rate of monomer, the pumping-out rate of the vacuum system for the product gas (which is hydrogen in many cases of plasma polymerization of hydrocarbons), and the characteristic hydrogen yield of a monomer associated with plasma polymerization. The relationships between these factors were established and examined for plasma polymerizations of acetylene, ethylene, and acrylonitrile.     

Active center formation in the modification of fibres by a gas discharge

Conclusions The basic feature of radical processes in polymers of various chemical structure on treatment in a gas discharge plasma is that the type of radicals formed in the polymer as a result of transfer of plasma energy to the macromolecule does not depend on the chemical composition of the plasma-forming gas.Radicals formed in the surface layer are mainly stabilized in the bulk of the polymer due to migration of a free valence. This plays an important role in carrying out chemical grafting in modifying the surface of fibres.Translated from Khimicheskie Volokna, No. 1, pp. 35–36, January–February, 1989.     

Polymerization of styrene in an electrodeless glow discharge

The polymerization (polymer deposition) rate of styrene in an electrodeless glow discharge from styrene vapor and a mixture of styrene vapor and gas (H₂, He, A, and N₂) was investigated. The rate of polymerization, R, was found to be independent of the discharge power. The rate of polymerization of the pure monomer was found to be proportional to the square of monomer pressure p_M. The addition of gas increased the rate of polymerization depending upon the partial pressure of the gas, p_x, and R can be generally expressed by R = a[p_M]²{1 + b[p_x]}. The value of b is dependent of the type of gas and follows the order of N₂, > A > He > H₂. The distribution of polymer deposition was found to be nearly independent of the partial pressure of the gas and of the discharge power with N₂ and H₂ as plasma gas; however, with He and A, the distribution is highly dependent on the partial pressure of the gas and on the discharge power. The study strongly suggests that polymerization occurs in the vapor phase and that the growing polymer radicals deposit on the surface of the discharge vessel, yielding highly crosslinked polymer deposition.     

Appearance of a boundary layer during the formation of viscose fibres

Conclusion 1. In the formation of viscose fibres, owing to the formation of a boundary layer, all the bath liquid in the space between the elementary fibres is immobilised as a boundary layer after a very short time.2. All this liquid receives an acceleration from zero velocity to a velocity equal to 90–92% of that of the thread. This acceleration is realised at a distance of 1.5–3 mm from the spinneret, and may cause considerable stresses in the elementary fibre being formed.All-Union Scientific-Research Institute for Man-Made Fibre (VNIIV). Translated from Khimicheskie Volokna, No. 6, pp. 33–35, November–December, 1969.     

Intensifying graft-polymerization in the process of modifying polycaproamide fibres

Conclusions -- The kinetics of the graft polymerization of dimethylaminoethyl methacrylate to polycaproamide fibre initiated by the redox systems Fe²⁺ - H₂O₂, Cu²⁺ - H₂O₂, and by an ROC containing a complex copper compound (Cu _c ²⁺ - H₂O₂) has been studied.-- An increase in the rate of graft polymerization, in the amount of grafted component, and the degree of useful conversion of the monomer has been found when the reaction is initiated by the ROS Cu _c ²⁺ - H₂O₂.Moscow Textile Academy. Translated from Khimicheskie Volokna, No. 3, pp. 11–12, May–June, 1992.     

Decontamination of the gaseous wastes in the manufacture of polycaproamide fibres

Conclusions Absorbers with a three-phase fluidized bed (centralized clean-up) and straight-through injectors (local clean-up) are very effective for decontaminating ventilation discharges containing caprolactam.The absorption process has been calculated in the recirculation of the absorbing agent in a closed loop.Translated from Khimicheskie Volokna, No. 2, pp. 57–59, March–April, 1983.     

Effect of glow discharge plasma on rhodium-based catalyst for oxygenates synthesis

Rhodium-based catalysts were prepared by impregnation, treated with glow discharge plasma, characterized by X-ray diffraction, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction, H₂ temperature-programmed desorption and CO temperature-programmed desorption, and investigated for oxygenate synthesis from CO hydrogenation. Based on the characterization results, plasma treatment endowed the samples with smaller particle size, higher dispersion of active components, and an enrichment of active components on the surface as well. As a result, the reducibility and adsorption properties were modified. In catalytic tests, the catalytic activity for CO hydrogenation over the samples treated by plasma was improved remarkably: the conversion of CO and the yield of oxygenates increased at most by a factor of 78.62% and 51.96%, respectively, while the selectivity of ethanol and methanol in the oxygenates was enhanced as well. Translated from Natural Gas Chemical Industry, 2006, 31(1): 21–24 [译自: 天然气化工]     

A study of the contact angle on RTV-silicone treated in a hydrogen glow discharge

A hydrogen glow discharge surface treatment followed by exposure to the atmosphere has been used to decrease the contact angle for distilled water on RTV-silicone. The change in contact angle has been studied in terms of vacuum ultraviolet irradiation, metastable bombardment, free-radical bombardment, and electrostatic charging. The study demonstrates that the decrease in the contact angle is caused by the interaction of the hydrogen atoms produced in the glow discharge with the polymer surface.     

Change in the properties of polycaproamide fibres in treatment with metal complex salts

The modifying effect of chromium and aluminum salts on the properties of polyamide films was demonstrated. The possibility of increasing chemisorption of metal cations by polycaproamide fibres by treatment with UHF radiation was investigated. __________ Translated from Khimicheskie Volokna, No. 3, pp. 33–34, May–June, 2007.     

Polymerization of organic compounds in an electrodeless glow discharge. VIII. Dependence of plasma polymerization of acrylonitrile on glow characteristic

The effects of experimental conditions (i.e., flow rate, pressure, discharge wattage, and glow characteristics) on the plasma polymerization of acrylonitrile were investigated. It was found that the glow characteristic is highly dependent on both flow rate and discharge wattage and that the plasma polymerization depends strongly on the glow characteristic. However, when experimental conditions are selected to maintain a fully developed glow in the tail flame portion of rf discharge, plasma polymerization is independent of discharge wattage and pressure. The polymer deposition rate is linearly proportional to the monomer flow rate. The deviations from this ideal situation are generally attributable to incomplete glow or partial glow under conditions which caused the deviation. The “character” of the glow largely determines the chemistry of the system. Consequently, the properties of polymers formed under different glow characteristics are also different.     

Electrochemical formation of Ni-Y intermetallic compound layer in molten chloride

The reduction of Y(III) ions in molten chloride is known to be a one-step three electron reaction [1, 2, 3], but a voltammogram of YCl₃ in molten LiCl-KCI-NaCl at a nickel electrode shows at least two reduction peaks of Y(III) ions, indicating the possibility of formation of Ni-Y intermetallic compounds. Using a galvanostatic electrolysis method, samples were prepared at several current densities at 450, 500, 600 and 700°C, respectively, and were identified with X-ray diffraction (XRD) and electron probe microanalysis (EPMA) methods. The results show that Ni₂Y, Ni₂Y₃ and NiY can be produced by electrolysis and Ni₂Y is found to be the predominant Ni-Y intermetallic compound under the experimental conditions. Nickel appears to diffuse in Ni₂Y faster than yttrium, and the diffusion process is the rate determining step during Ni₂Y formation.