Determination of acid impurity content in spinning solution and in freshly spun fibre made from aromatic polyamides

Conclusions The spinning solution from the manufacture of fibre from an aromatic polyamide contains dissolved HCl in the free form and HCl bonded to functional groups of the polymer; the freshly spun fibre contains only bonded HCl.A procedure has been developed for determining the content of free and bound HCl in spinning solution and freshly spun fibre; it is based on titrating a sample of a specimen in a medium of dimethylacetamide containing 3% LiCl with an approximately 0.04-molar alcoholic KOH solution.Translated from Khimicheskie Volokna, No. 2, pp. 58–60, March–April, 1990.     

A rapid method of determining the aromatic polyamide content of dimethyl acetamide

Conclusions -- A rapid method of determining the polymer content of spinning solution in the concentration range from 7–20% by wt. has been developed; it is based on precipitation of the polymer in acetic anhydride, extraction of the solvent, and subsequent titration of it with perchloric acid. A comparison of the results obtained using the rapid procedure and the dry residue method has been carried out.-- The procedure developed is characterized by accuracy and rapidity in the determination.Translated from Khimicheskie Volokna, No. 5, pp. 59–60, September–October, 1990.     

Instability in polyethylene oxide solutions in a hydrodynamic field

It is found that degradation in aqueous polyethylene oxide is accompanied by dehydration and aggregation, with deterioration in the thermodynamic affinity for water, which is not related to molecular-mass reduction.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 2, pp. 230–235, February, 1988.     

Radiation-chemical synthesis of polypropylene fabrics with sulfonic acid functional groups

A sorption-active material carrying sulfonic acid groups was synthesized by the radiation-induced graft polymerization of styrene monomer onto the surface of non-woven polypropylene fabric, followed by sulfonation of the grafted polystyrene chains. The effect of the main experimental parameters (absorbed dose, monomer concentration, reaction time) on the styrene degree of grafting was investigated. The sulfonation process with 5% chlorosulfonic acid at room temperature was investigated in detail and the optimal sulfonation conditions for the samples with a medium degree of grafting (70-140%) were determined. Densities of 3.5-5 meq/g were obtained by applying those sorption-active PP fabrics with a sulfonic acid group.     

Effect of exposure to optical radiation and temperature on the electrical and optical properties of In2O3 films produced by autowave oxidation

Indium-oxide films are synthesized by the autowave-oxidation reaction. It is shown that, upon exposure to optical radiation, the resistance of the films sharply decreases and the maximal relative change in the resistance is 52% at room temperature. Two resistance relaxation rates after termination of the irradiation, 15 Ω s^?1 during the first 30 s and 7 Ω s^?1 over the remaining time, are determined. The data of infrared spectroscopy of the films show that exposure to optical radiation induces a 2.4% decrease in the transmittance at a wavelength of 6.3 μm. It is found that, after termination of the irradiation, the transmittance gradually increases with a rate of 0.006% s^?1. It is suggested that photoreduction is the dominant mechanism responsible for changes in the electrical and optical properties of the In₂O₃ films.     

Application Method for Protective and Electrical Insulating Ceramic Coatings by Microarc Oxidation Under Excess Pressure Conditions

Refractories and Industrial Ceramics - Results are given for development of technology for electrolytic deposition of protective and electrical insulating ceramic coatings. The technology developed...     

Detection and serological screening of conditionally-pathogenic enterobacteria isolated from food products and the environment

The spread of some coliform bacteria in foods, the faeces of children and adults and in human environment was studied, and the evaluation of their toxigenic potential and serological properties was given. More then 160 strains of enterobacteria including 70 strains of Escherichia spp were described. The frequency of detection enterotoxigenic E. coli in foods--18%--was approximately similar an amount of ETEC strains which was isolated in humans (22%). 3 strains of E. coli) 157 were found in foods and in clinical samples (1.9%). The observed results have confirmed the proposal about the increasing of ETEC E. coli food-borne transmitting and dissemination its in the environment.