Secondary cellulose acetate hollow nanofiltration fibre

The studies showed that addition of certain amounts of glycerin and PEG to solution causes corresponding changes in structure and allows obtaining hollow fibres with nanofiltration properties. The parameters for spinning a hollow nanofiltration fibre for purification of part of the wastes from production of viscose fibres were developed based on the data obtained.All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated from Khimicheskie Volokna, No. 3, pp. 38–43, May–June, 1994.     

Hollow fibre based on polyphenylene isophthalamide as the highly-porous backing

Conclusions -- The possibility of preparing a highly-permeable backing from polyethylene isophthalamide in spinning composite hollow fibres for gas separation has been demonstrated.-- A connection has been established between spinning parameters and their effect on the gas permeability of the backing.-- A regime for the preparation of hollow fibres which have an optimum morphological structure for the wall pore structure has been determined.Translated from Khimicheskie Volokna, No. 4, pp. 47–48, July–August, 1991.     

Use of hollow polysulfone fibres in the process of dehydrating acetic acid by evaporation through a membrane

Conclusions By use of the double coagulation bath method, membranes have been made from polysulfone having an effective selective layer thickness of 2.5 µm. The limiting size of hollow fibres is as follows: external diameter, 1 mm; internal diameter, 0.6 mm. It was not possible to obtain a surface layer free of defects on increasing the diameter.In the membranes prepared, more than 50% of the resistance to mass-transfer is concentrated in the porous layer.It has been found that the selective layer of the membrane has a critical thickness (which depends of the nature of the polymer, the solvent, and other factors), below which selectivity begins to decrease.In evaporation through a membrane, a dependence of the result of studies on the internal diameter — hollow fibre length was discovered.In an experiment on evaporation through a membrane at 36 K, for the system 80% acetic acid — water, using hollow fibres a selectivity of 116 and a flux of 0.1 kg/m² were obtained.Translated from Khimicheskie Volokna, No. 3, pp. 38–41, May–June, 1993.     

Spinning of hollow and matrix fibres from polysulfone melt

The possibility of fabrication was demonstrated and the basic technological parameters for spinning polysulfone fibres by the high-production melt method were determined. The polysulfone fibres developed were used as matrix and hybrid structures; thermostable composites with elevated physicomechanical properties were fabricated from such semifinished products.V. V. Gorlov participated in fabrication of the hollow fibres.Translated from Khimicheskie Volokna, No. 6, pp. 29–31, November–December, 1994.     

Spinning hollow fibres from polyacrylonitrile into degassed baths

Conclusions Changes in the properties of water as a result of degassing by heating have been examined.Degassing the water which is used as a precipitant in spinning hollow fibres of PAN permits one to exert a directed action on their properties.Translated from Khimicheskie Volokna, No. 1, pp. 15–17, January–February, 1989.     

Selective properties of hollow fibres for ultrafiltration

Conclusions The selective properties of hollow fibres used in the separation of solutions of poly-ethylene glycols and proteins have been investigated. It has been shown that the increase in retention coefficient and specific permeability as the velocity of the stream increases, in the separation of solutions of kinetically relatively flexible polyethylene glycol molecules, is not connected with the phenomenon of concentration polarization. but can be explained by the deformability of the tangles of polyethylene glycol macromolecules on flow of the solution in thin capillaries (hollow fibres).Optimum ultrafiltration conditions have been determined.Complete retention curves have been constructed for the hollow fibre, which make it possible to determine its region of use.Translated from Khimicheskie Volokna, No. 6, pp. 14–16, November–December, 1984.     

A study of porosity in active surface in modified carbon fibres

Conclusions -- The primary adsorption center content of modified ÉLUR-M carbon fibres depends on the conditions of the surface activation process: after electrochemical treatment, more of them are contained than after treatment with ozone.-- In electrochemical treatment of carbon fibres, an optimum zone of intensity of this process is observed, for which the formation of the largest number of active centers is characteristic.-- The number of active centers which are formed on the surface of type LU carbon fibres depends on the final pyrolysis temperature and is caused by structural—chemical processes during carbonization of the material.-- The investigated carbon fibres are ultramicroporous materials with a pore diameter no greater than 6–7 Å and a total pore volume of 0.03–0.09 cm³/g.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 33–35, May–June, 1991.     

Comparative evaluation of the thermal properties of aromatic fibres (polyoxazole,polyimide, and polyaramid)

The thermal properties of the aromatic fibres Arselon, Arselon-C, Arimid, and Armos, as-spun and heat-treated are investigated using methods of thermomechanical and dynamic thermogravimetric analysis and differential scanning calorimetry. According to the TMA data, Arselon, Arselon-C, Arimid, and heat-treated Armos fibres retain size stability up to 400°C. Shrinkage is no more than 1–2%. As-spun Armos fibres lengthen insignificantly (under 7%). The temperature characteristics of aromatic fibres obtained by TGA and DSC show that thermooxidative degradation markedly begins at temperature above 390–400°C.Translated from Khimicheskie Volokna, No. 5, pp. 45–48, September–October, 2004.     

Ultrastrong fibres fabricated by orientational crystallization from gel. A review

The methods of fabrication of ultrastrong chemical fibres from flexible-chain polymers examined in the review require use of a starting polymer with an ultrahigh-molecular-weight. Attaining ultrahigh draw ratios is a common technological condition. This is almost exclusively determined by the ratio between the deformation rate, temperature, and initial state of the polymer. Gel technology is a priority method of fabrication of ultrastrong fibres. The polyester fibres fabricated by this method attain strengths of 6–7 GPa and Young's modulus of 220–250 GPa. All ultrastrong fibres have the structure of a fibrillar crystallite with a significant fraction of KVTs. All ultrastrong fibres have a melting point 5–10°C higher than for oriented fibres and elevated technical stability with high temperatures and moderate loads.Ukrainian Scientific-Research Institute of Fibres, Kiev. Translated from Khimicheskie Volokna, No. 6, pp. 8–17, November–December, 1992.     

Synthesis and characterization of hollow zeolite microspheres with a mesoporous shell by O/W/O emulsion and vapor-phase transport method

Hollow microspheres of ZSM-5 with a mesoporous shell have been synthesized through formation of amorphous hollow SiO₂/Al₂O₃ microspheres by sol–gel process in multiple oil–water–oil emulsions and transformation of the amorphous species into zeolite by water–organic vapor-phase transport treatment at 160 °C for 8 days. The morphology of the amorphous and zeolite spheres observed by scanning electron microscopy shows no significant change whereas the molar ratio of Si/Al increases from 6 to 20 during the transformation. The structural feature of zeolite was characterized by X-ray diffraction and ²⁹Si and ²⁷Al magic-angle spinning nuclear magnetic resonance. Transmission electron microscopy and N₂ adsorption–desorption isotherms indicate that uniform mesopores in the shell of zeolite spheres arise from the interstices among zeolite crystallites.     

Effect of a constant magnetic field on the mechanical properties of container glass

The results of industrial tests on treatment of container glass with a constant magnetic field are reported. Thermomagnetic treatment increased the strength of jars by 20–30%, and the hardness of the glass also increased. The advantages of the proposed method of increasing the reliability of industrial glassware were noted.Translated from Steklo i Keramika, Nos. 3–4, pp. 17–18, March–April, 1994.     

Mechanism of the thermal transformations of polyacrylonitrile fibres in oxidation

Conclusions 1. The mechanism of the physicochemical transformations of PAN fibres which take place in an atmospheric oxygen medium at 200°C has been studied, and the time intervals for their occurrence have been established.2. It has been found that on heat treatment of PAN fibres for 3–4 h, dehydration reactions mainly take place; and on increasing the time from 3 to 9 h, mainly cyclization reactions take place. Intermolecular condensation reactions, which lead to the formation of polynuclear planar aromatic structures, take place after 11–12 h of heat treatment.3. A new approach has been proposed for interpreting DTA data, based on analysis of the components of the DTA curve equation, and also DTA parameters for control of the process of thermooxidative treatment of PAN fibres.4. It has been found by the XSA method that the cross-linking process leads to the formation of two-dimensional structures. An x-ray analysis figure has been proposed which makes it possible to discern the time intervals for occurrence of cross-linking.Translated from Khimicheskie Volokna, No. 5, pp. 8–11, September–October, 1993.     

Modification of polycaproamide,its structure and certain properties

Conclusions -- Structural features and physico-mechanical properties of fibres based on polycaproamide modified with 0.5–2.0% by wt. of aromatic chromophoric diamines have been studied.-- Spectral—luminescence characteristics of fibres and films based on modified PCA have been described; a light-stabilization effect has been detected and, in some cases, an antiradiation action of the chromophoric groups.The authors express thanks to N. M. Bol'bit for investigation of the light-and radiation-resistance of fibres and to A. N. Ozerin for participating in discussions of the results obtained.Translated from Khimicheskie Volokna, No. 1, pp. 44–47, January–February, 1991.     

Spectroscopic investigation of polymers dyed with fluorescent dyes — Naphthalimide derivatives

Conclusions 1. Naphthalimide derivatives are promising for the preparation of dyed and fluorescing polyamide, and especially acetate fibres. Thereupon dyeing of the fibres in bulk is a more economical and ecologically clean method than dyeing from solutions.2. The optimum dye concentration in the fibre — about 0.5% by weight — at which the fibre acquires a bright color and fluoresces intensively has been determined.Scientific Research Institute of Physical Chemistry, Moscow. Translated from Khimicheskie Volokna, No. 5, pp. 16–18, September–October, 1993.     

Special features in spinning high-modulus viscose fibre of high linear density

Conclusions On transition to spinning 0.13–0.17 tex HMV fibres to 0.22–0.44 tex fibres, to maintain diffusion conditions in spinning, the H₂SO₄ content of the precipitation bath should be kept at a level of 70–75 g/liter or increased by no more than 1–2 g/liter. Process stability is achieved by reducing the spinning speed. However, the round cross-sectional form of the fibre is not retained, and its physicomechanical properties are diminished.A further rise in fibre quality may be attained by invreasing the -Cellulose content of the viscose to 7.5% by wt., with a simultaneous increase in the viscosity of the viscose to 250–300 sec.Translated from Khimicheskie Volokna, No. 4, pp. 28–29, July–August, 1989.     

Preparation and properties of viscose staple fibre modified by grafting polyvinyl chloride

Conclusions 1. The authors have obtained modified viscose fibres containing PVC in amounts reaching 25–230% of the weight of cellulose. The molecular weight of the grafted chain varies between 40,000 and 140,000; the degree of conversion of cellulose does not exceed 13–22%.2. It is shown that grafting of PVC increases the absolute strength and elongation of fibres, reduces the loss of wet strength, and reduces the resistance to repeated bending. A marked reduction of the fibre number reduces their strength.3. The results are explained by the probability that graft copolymerization takes place on a supramolecular level.Moscow Textile Institute. Translated from Khimicheskie Volokna, No. 5, pp. 30–32, September–October, 1969.     

Some features of spinning hollow fibres from polycarbonatesiloxane melts

Conclusions The following parameters have been determined as a result of calculations: fibre tension, solidification path length, and the change along the spinning path of the following: stretching stresses, speed, radius, wall thickness, and fibre temperature.It has been shown that, with increase in take-up speed, the length of the section of fibre deformation is reduced, varying practically proportionally to the flow rate of the polymer system.Stability of the process of spinning hollow fibres from polycarbonatesiloxane melts is assured within a narrow range of stretching force.Translated from Khimicheskie Volokna, No. 3, pp. 41–43, May–June, 1989.     

Modification of polyacrylonitrile fibres to improve the properties of carbon fibres prepared from them

Conclusions -- It has been found that treatment of acrylonitrile fibres obtained by the wet dimethyl formamide method before thermal oxidation with inorganic salts considerably changes the properties of the thermally oxidized fibres.-- On treatment of the fibres with an aqueous solution containing copper ion in a reducing medium, their sorptive powers are considerably impaired, the fibre diameter is increased, and the electrical conductivity is increased, plus processes of cyclization and oxidation are accelerated.-- On treatment with a solution of aluminum chloride in the presence of orthophosphoric acid, the fibre structure is made denser and its strength is increased.-- Sodium thiosulfate as a modifier considerably changes the functional composition of polyacrylonitrile fibres; thereupon, a process of structural amorphization takes place.Translated from Khimicheskie Volokna, No. 5, pp. 48–50, September–October, 1991.     

Fabrication of VION chemisorption fibre in concentrated solutions of hydrazine hydrate

The mechanism of the reaction of hydrazidation of Nitron fibre in aqueous and alcohol solutions of hydrazine hydrate in the 10–75 wt. % concentration range was investigated. The conditions for fabrication of an anion-exchange fibre with a static exchange capacity (SEC) of up to 3 meq/g by successive treatment of Nitron fibre with solutions of hydrazine hydrate with a concentration of 10 to 50% were developed. The chemisorption fibres obtained have satisfactory mechanical properties and satisfy the requirements set for them in textile processing.Military Academy for Chemical Defense, All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated from Khimicheskie Volokna, No. 2, pp. 15–17, March–April, 1995.     

Efficiency of flame-proofing action of flame-proofers for fibres of aromatic polyamides

Conclusions The possibility of raising the oxygen index of fibres of aromatic polyamides by use of organophosphorus or chlorinated organic compounds has been examined. It has been shown that, to obtain modified fibres whose fire-protected effect is resistant to wet treatment, it is necessary to introduce glycasine additionally into the fibre.As a result of investigating the physicomechanical properties of the original and flame-protected fibres, it has been found that the use of organophosphorus compounds for the modification of fibres from aromatic polyamides is more advisable.Translated from Khimicheskie Volokna, No. 6, pp. 18–20, November–December, 1983.