Preparation of a fibre-forming sulfonic acid copolymer and its properties

Conclusions The basic principles in synthesis of a fibre-forming sulfonate group-containing copolymer have been established.It has been shown that the sulfonate group content of a copolymer shows up in its properties and the properties of its dilute solutions.Translated from Khimicheskie Volokna, No. 2, pp. 16–17, March–April, 1988.     

The Fluorescent Quantum Efficiency of Copolymers Containing Coumarin-6 at the Side-chain

Coumarin-6 containing acrylates (CA) with different spacers were synthesized. Copolymers of CA with methyl methacrylate (MMA) in CA/MMA in the weight ratios of 1/20, 1/40 and 1/60 were prepared by using AIBN as initiator. The copolymer compositions were determined from uv-visible spectroscopic analyses, according to Beer’s law. UV absorption and photoluminescence (PL) spectra indicated a concentration quenching, which increased with increasing coumarin-6 concentration in the copolymer compositions and also increasing the spacer length from the copolymer to coumarin-6 moiety, leading to a decreased fluorescence efficiency (φ_s/φ_o) as well as a red shift of λ_max. Furthermore, as the spacer, n in –(CH₂)_n–, increases from n=2, 3 to 6, excimers formed due to overlap of chromophores, resulting in the splitting of the PL emission band and lowering the PL intensity. Experimental results revealed that when the ratio of CA/MMA=1/60 and the spacer n=2, the copolymer film showed an optimized fluorescent quantum efficiency.     

Morphological and structural features of polyacrylonitrile fibres spun by the dry-wet method

Conclusions -- A technological regime for the preparation of polyacrylonitrile fibres from binary and ternary copolymers has been chosen; these differ from known specimens in having a more uniform cross-sectional structure and a smoother elementary filament surface.-- A considerable difference in crystalline structure of fibres from binary and ternary copolymers which have been spun into a dimethyl sulfoxide—water bath has been shown.-- Fibres from the binary or ternary copolymer which have been spun into a precipitation bath having a large dimethyl sulfoxide content in water are characterized by a lower degree of swelling.-- Shrinkage of fibres from the binary copolymer in the temperature range 200–220°C is twice as small as the shrinkage of fibres from the ternary copolymer.Deceased.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 19–22, May–June, 1991.     

The preparation of fibrous anion-exchange resins based on a graft copolymer of polycaproamide-polyglycidyl methacrylate and polyethylene polyamine

Conclusions -- A mathematical model for the amination reaction of the PCA-PGMA graft copolymer has been constructed which adequately describes the process.-- The problem of optimizing the process of aminating the PCA-PGMA graft copolymer with polyethylene polyamine has been solved. The chemisorbents prepared at the optimum regime have an SEC of up to 3.7 meq/g.Translated from Khimicheskie Volokna, No. 5, pp. 34–35, September–October, 1991.     

Molecular weight distribution of acrylonitrile-2-methyl-5-vinylpyridine copolymers

Conclusions A fractionation of an acrylonitrile-2-methyl-5-vinylpyridine copolymer with respect to composition and molecular weight has been carried out by the fractional precipitation method. The distribution of the copolymer with respect to composition has a bimodal character, which may exert an effect on the properties of solutions and fibres.The parameters and K in the Mark-Kuhn-Houwink equation have been determined by the sedimentation method; they are equal to 0.89 and 2.062×10^–4, respectively.Translated from Khimicheskie Volokna, No. 5, pp. 17–18, September–October, 1985.     

Spinning of a chemisorptive sulfonic acid fibre

Conclusions Special features of spinning a fibre by the wet method from a copolymer based on acrylonitrile and sodium methallylsulfonate which are connected with dissociation and solvation of the sulfonate groups have been examined.It has been found that, to obtain a fibre with satisfactory physico-mechanical properties which assure processing into textile articles from a sulfonate-containing copolymer, it is necessary to carry out the spinning either into nonaqueous baths or into aqueous baths which contain lyophilic salts.Translated from Khimicheskie Volokna, No. 3, pp. 10–12, May–June, 1988.     

Preparation of a chemisorptive sulfonate fibre and its properties

Conclusions Conditions have been developed for preparation of a chemisorptive fibre containing sulfonate groups from an acrylonitrile-sodium methallylsulfonate copolymer which processes satisfactorily into textile articles.During the process of orientation stretch of the fibre prepared, strengthening takes place as a result of orientation of the acrylonitrile component.Translated from Khimicheskie Volokna, No. 4, pp. 8–9, July–August, 1988.     

Modified chemisorptive fibres based on a copolymer of acrylonitrile with 5-vinyl-2-methylpyridine

Conclusions Conditions for the preparation of salt forms of a chemisorptive fibre based on a copolymer of acrylonitrile and 5-vinyl-2-methylpyridine have been worked out.It has been found that the formation of stable salt forms of the copolymer is determined by the basicity of the pyridine groups.The effect of the basicity of the functional groups and salt forms of the polymer on the equilibrium and kinetic characteristics of fibres in the sorption of gases of acid or basic character has been shown.Translated from Khimicheskie Volokna, No. 1, pp. 22–24, January–February, 1988.     

Association properties of a high molecular weight poly(propylene oxide–b–ethylene oxide) diblock copolymer in aqueous solution

Summary Summary A high molecular weight poly(propylene oxide–b–ethylene oxide) diblock copolymer was prepared via sequential anionic suspension polymerization using a calcium amidealkoxide initiating system. ¹H nuclear magnetic resonance, viscometry and static and dynamic light scattering have been used to characterize the copolymer and to examine its self–assembly in aqueous solution. The copolymer was found to self–associate in a narrow concentration range above a certain critical aggregation concentration. The weight–average molecular weight, the radii of gyration, the second virial coefficients, the diffusion coefficients, and the hydrodynamic radii of the particles in both unimer and aggregate regions were determined. Aggregates of low aggregation number (2–3) were formed. Dynamic light scattering measurements performed in a wide concentration range revealed an enhanced aggregate stability towards dissociation upon dilution.     

Kinetic conditions for the forced transition of macromolecules of an acrylonitrile copolymer into the uncoiled state

Conclusions -- The transition of the macromolccule of an acrylonitrile copolymer into the uncoiled state in lengthwise flow of aqueous salt solutions at concentrations from 1 · 10^–3 to 5 · 10^–2 g/cm³ has been studied.-- The critical velocity gradients at which the tangled state of the macromolecules becomes unstable in a lengthwise field have been determined. It has been shown that the values of these agree well with predictions of the theory of semidilute polymer solutions.Translated from Khimicheskie Volokna, No. 2, pp. 19–21, March–April, 1993.     

Viscosity properties of acrylonitrile-sodium methallylsulfonate copolymer solutions

Conclusions To obtain structurally uniform solutions of the acrylonitrile-sodium methallylsulfonate copolymer, it is advisable to prepare them at elevated temperatures.An effect of structural homogenization of concentrated solutions of the copolymer has been detected in the process of temperature treatment at 60–80°C.Translated from Khimicheskie Volokna, No. 2, pp. 27–28, March–April, 1986.     

Some features of fibre preparation from a copolymer of acrylonitrile with 5-vinyl-2-methylpyridine

Conclusions Increasing the content of ionogenic grups in a copolymer of acrylonitrile with 5-vinyl-2-methylpyridine leads to a change in intermolecular interaction is solutions of the polymer, and this exerts an effect on their rheological properties.The parameters of the process of spinning and fibre strengthening are determined by the composition of the copolymer, a change in fibre properties being observed at a content of active groups in the copolymer which is greater than 40% by wt.Translated from Khimicheskie Volokna, No. 3, pp. 17–19, May–June, 1986.     

Pilot plant realization of a process for preparing a chemisorptive polyamide fibre

Conclusions A technological process for the preparation of the chemisorptive polyamide fibre KM-Al, which is based on a graft copolymer of polycaproamide and poly(dimethylaminoethyl methacrylate) has been developed and realized on a pilot plant assembly of the Volzhskii Khimvolokno PO.Sorption-filtering materials from KM-Al fibre can be used in installations for the sanitary purification of gases and in universal media for individual protection of breathing organs — respirators.Translated from Khimicheskoe Volokna, No. 6, pp. 35–36, November–December, 1986.     

Brightening and sizing preparation for finishing viscose textile yarn

Conclusions A brightening and sizing preparation has been developed which is based on a copolymer having a high content of acrylic ester units, prepared by a one-stage, high-temperature hydrolysis of an acrylonitrile copolymer in the presence of a mixture of water and an aliphatic alcohol.Use of this preparation (as compared with the use of polyvinyl alcohol) ensures a 15–25% reduction in breakage and amount of waste in rewinding viscose textile yarn.Translated from Khimicheskie Volokna, No. 2, pp. 27–28, March–April, 1988.     

Effect of radiation cross-linking on the thermomechanical properties of fibres from a tetrafluoroethyleneethylene copolymer

Conclusions The effect of radiation dose on the heat-resistance of fibres from a tetrafluoroethyleneethylene copolymer has been investigated.It has been shown that, as a result of irradiation, the use temperature of the fibres can be raised by 80°C.Translated from Khimicheskie Volokna, No. 1, pp. 37–38, January–February, 1988.     

Rheological properties of solutions of graft copolymers of polyvinyl alcohol and polyacrylic acid

Conclusions The activation energy of viscous flow of systems containing the PVA-PAA graft copolymer is considerably higher than that for solutions of PAA; the activation energy of viscous flow of solutions of mechanical mixtures of PVA and PAA is higher than that of mixtures of PVA with the graft copolymer. This fact is a convincing confirmation of the compatibility of the PVA-(PVA-PAA) graft copolymer system.The compatibility of this system is also shown by the high stability of the solutions. Thus, 12.5% solutions of the mixture of PVA and the graft copolymer in a ratio of 4/1 do not separate into layers during 3–4 days. The achievement of the compatibility of a mixture of the polymers mentioned by grafting is an important advantage obtained by the modification of polymers by the method of graft copolymerisation.All-Union Correspondence Institute of the Textile and Light Industries. Translated from Khimicheskie Volokna, No. 2, pp. 27–29, March–April, 1969.     

Conducting block copolymers. Towards a polymer pn- junction

Summary The synthesis of polyphenylacetylene (1), polypentafluorophenylacetylene (2) and the block copolymer of 1 and 2 polyphenylacetylene-polypentafluorophenylacetylene (3) using a Rhodium catalysed living polymerisation reaction is presented. Photoelectron spectroscopy of thin films of the individual polymers using 50eV photons from a synchrotron allowed for the determination of the position of the the electronic energy levels, ionisation potentials and the vacuum level shift which indicated that the block copolymer organises at the gold substrate surface such that the fluorinated part of the copolymer extends towards the air interface. Pulse radiolysis time resolved microwave conductivity (PR-TRMC) allowed for the determination of the minimum carrier mobilities and the carrier lifetimes. The sum of carrier mobilities, _min, were respectively 5.2·10^–7, 6.3·10^–7 and 3.2·10^–7m² V^–1 s^–1 and the first half life, _1/2, was 2.0, 1.5 and 1.0 s in 1, 2 and 3. The study shows that it is possible to make conducting block copolymers by the rhodium catalysed polymerisation of arylacetylenes with different electronic energies that organises at the surface giving rise to electronic properties that approach analogy to the traditional inorganic semiconductor pn-junctions.     

Oriented polycrystalline mesoporous CeO2 with enhanced pore integrity

Mesoporous CeO₂ particles are synthesized using a sol–gel method involving Pluronic P123 or F127 tri-block copolymer and cerium acetate hydrate. Transmission electron microscopy reveals well defined meso-channels of about 10 nm in diameter and a wall framework consisting of highly oriented polycrystalline CeO₂. The [0 0 1] axis of the crystals is found to be aligned parallel to the meso-channels, and lattice coherency of [1 0 0] or [0 1 0] also exists in perpendicular plane to the channel. A cooperative self-assembly of the tri-block copolymer and Ce⁴⁺ species is believed to occur, along with the precipitation of nano-crystalline CeO₂ in the sol–gel process. It is proposed that the preferential orientation may result from a favored linkage of the low-order Miller indices {0 0 1} planes of CeO₂ to the PEO segment in the PEO–PPO–PEO tri-block copolymer micelles. The unique structural characteristics of meso-CeO₂ appear to contribute to maintaining the pore integrity during the synthesis as well as in a post-fabrication in situ TEM heating test.     

Structure and properties of yarn from a mixture of a heterocyclic polyamide and polyacrylonitrile

Conclusions Conformational-morphological features of yarns prepared from a mixture of polyamidobenzimidazole (PABI) and a copolymer of acrylonitrile and methyl acrylate (CPAN) have been studied.Two mechanisms for the effect of CPAN on the properties of PABI have been found. In the first stage, a small addition of CPAN (0.1–1%) exerts an alloying effect on the PABI, which consists is increasing the degree of orientation of its macromolecules, increasing yarn uniformity, eliminating micro- and macrodefects in the yarns, and densifying the system as a whole. However, at a 5% CPAN content of the system, regardless of the fact that all the specific structural effects enumerated above are preserved, the strength of contact interaction in the intermicro- and the intermacrofibrillar space is reduced due to localization of the carbonized CPAN.Translated from Khimicheskie Volokna, No. 6, pp. 24–26, November–December, 1987.     

Producing a fibre-forming copolymer of acrylonitrile with vinylene carbonate in homogeneous conditions

Conclusions 1. We have studied the copolymerization of AN with VC in homogeneous conditions. We calculated the copolymerization constants to be r_AN=14.9±0.1; r_VC=0.085±0.001.2. We selected conditions for producing fibre-forming copolymer, and obtained fibre with satisfactory mechanical indices.All-Union Scientific-Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 4, pp. 50–51, July–August, 1969.