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Kravchuk, L. S.; Radkevich, V. Z.; Lysenko, G. N.

doi:10.1023/a:1024846614078

Fibre Chemistry

2003

DOI: 10.1023/a:1024846614078

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L. S. Kravchuk

V. Z. Radkevich

G. N. Lysenko

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Cited by 3 publications

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“…The initial value of the g factor of 1.975 does not change, which indicates preservation of the initial degree of oxidation of 3+ by the chromium ions. Sulfur dioxide is one of the products of thermal decomposition of this sulfo cation exchanger [9]. For the sulfur ions in sulfo groups in a 5+ degree of oxidation, it is logical to hypothesize the occurrence of a disproportionation reaction with formation of sulfate anions.…”

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Effect of Chromium Ions on Degradation of Fiban K-1 Fibrous Sulfocation-Exchanger

et al. 2005

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It was shown that the mechanism of thermostabilization of the substituted chromium form of the fibrous sulfo cation-exchanger Fiban K-1 is due to the formation of chromium complexes and polystyrene sulfonic acid and then sulfates.Dehydration and irreversible degradation of the polymers are considered the basic stages of thermal degradation of sulfo cation-exchangers [1]. By adding metal ions to an ion exchanger, it is possible to accelerate, or on the contrary, inhibit this process [2,3]. Formation of ion-exchange sulfo complexes during heating could be one cause of the increase in the thermal stability of the metal-substituted forms of cation exchangers and they on one hand cause cross linking of the polymer chains and on the other can retain coordination water, as this occurs in the case of a copper-substituted cation exchanger [4]. We investigated the mechanism of the effect of chromium ions on the thermal stability of Fiban K-1 sulfo cation-exchanger. This cation was selected because some of its sulfates totally lose coordination water only when heated in a vacuum. In the case of formation of an ion-exchange sulfo complex in a chromium-substituted cation exchanger, a shift in the dehydration stage and consequently the entire decomposition process in the higher temperature region can be predicted.Manufacture of the Fiban fibrous sulfo cation-exchanger was described previously in [5]. The chromium form was obtained by passing a chromium nitrate solution (in excess) through the cation exchanger. After exchange, the sample was washed with distilled water until NO 3 ions were totally absent.The initial N-K-1 ion exchanger and its chromium form Cr-K-1, in which all hydrogen ions were substituted by Cr 3+ ions, were investigated. Air-dried samples were investigated by differential thermal analysis (DTA) and IR and EPR spectroscopy were used to investigate them after heat treatment in air at 200, 300, 400, 415, and 450°C.The derivatographic analysis was performed on a PaulikPaulikErdey instrument in the 20-500°C temperature range in air. The IR spectroscopic studies were conducted on a Nicolet Protege 460 Fourier IR spectrophotometer. The samples were molded into pellets with previously dried KBr. The spectra were recorded at room temperature in air and in a vacuum. The EPR spectra were recorded at 20°C in air on a modified RE-1306 spectrometer with computer support (λ = 3 cm). The values of the g factors were measured with MgO external standard containing Mn 2+ ions.The integral and differential weight loss curves for the initial cation exchanger (curves 1) and its chromium form (curves 2) on heating are shown in Fig. 1. The first peak on both differential curves (Fig. 1b) basically characterizes the temperature region of loss of water. The initial Fiban loses water up to ~40°C and begins to intensively decompose above this temperature. The decomposition rate maximum in the second stage is attained at 250°C, and the rate then clearly decreases up to ~370°C. The third stage of weight loss then begins, and the decompo...

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Effect of Chromium Ions on Degradation of Fiban K-1 Fibrous Sulfocation-Exchanger

et al. 2005

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Thermal behaviour of polyacrylamidoxime–copper chelates

Moroi¹,

Bı̂lbă

Bilba

et al. 2006

Polymer Degradation and Stability

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Hydrophilization of a Porous Polytetrafluoroethylene Supporter by Radiation Grafting Poly(Acrylonitrile-co-Sodium Allylsulfonate)

박병희¹,

손준용²,

윤기석

et al. 2014

Polymer Korea

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We prepared hydrophilic porous supporters for the reinforced composite fuel cell membrane by radiation grafting of acrylonitrile (AN) and hydrophilic sodium allylsulfonate (SAS) into a porous polytetrafluoroethylene (PTFE) supporter. The physicochemical properties of the supporters prepared under various reaction conditions such as molar ratio of SAS/AN, monomer concentration, and irradiation dose were evaluated. FTIR was utilized to confirm the successful introduction of SAS/AN copolymer chains into the porous PTFE. The pores of the porous PTFE film were found to be decreased with an increase in the degree of grafting by using FE-SEM and gurley number. Furthermore, by analyzing the degree of grafting, contact angle, and TBO (toluidine blue O) uptake, the hydrophilicity of the prepared supporters was found to increase with an increase in the degree of grafting.

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Cited by 3 publications

References 2 publications

Effect of Chromium Ions on Degradation of Fiban K-1 Fibrous Sulfocation-Exchanger

Effect of Chromium Ions on Degradation of Fiban K-1 Fibrous Sulfocation-Exchanger

Thermal behaviour of polyacrylamidoxime–copper chelates

Hydrophilization of a Porous Polytetrafluoroethylene Supporter by Radiation Grafting Poly(Acrylonitrile-co-Sodium Allylsulfonate)

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