Evaluating the quality of caprolactam from toluene

Conclusions -- It has been found that the standard indices are necessary but not sufficient for a complete evaluation of the quality of caprolactam intended for the preparation of fibre-forming polycaproamide.-- The preferability of using a spectrophotometric method involving a color reaction withp-dimethylaminobenzaldehyde to evaluate the content of undesired admixtures of carbonyl compounds not regulated by the All-Union State Standard in caprolactam has been demonstrated.Translated from Khimicheskie Volokna, No. 5, pp. 51–54, September–October, 1990.     

Condensation of caprolactam vapor in the synthesis of polycaproamide under vacuum

Conclusions It is recommended to use a mixture based on caprolactam and benzoic acid, with small amounts of added water, for the low-temperature condensation of CL vapor in the synthesis of PCA under vacuum.Condensation of CL vapor at a temperature below 333°K permits one to return 7–9 kg of CL per ton of polymer to the technological cycle.The use of low-temperature condensation permits one to reduce the concentration factor of lactam in water from the steam-ejector pumps by a factor of more than 30 and to effect water recycling.Translated from Khimicheskie Volokna, No. 5, pp. 23–24, September–October, 1983.     

Relationship between the solubility of water vapour in caprolactam and its partial pressure and temperature

Conclusions It has been shown that the solubility of water vapour in a caprolactam melt decreases sharply with an increase in temperature, and also in the presence of acetic acid and a protective gas. Therefore, to increase the concentration of water in a caprolactam melt it is advantageous to use non-volatile molecular weight regulators and water vapour as the protective gas in the first section of a continuous polymerization tube.First communication in a series Investigation into the chemistry and technology of polycaproamide.Ivanov Chemical Technology Institute. Translated from Khimicheskie Volokna, No. 3, pp. 7–9, May–June, 1969.     

Stability of caprolactam on storage under manufacturing conditions

Conclusions Caprolactam which has starting quality indices that conform to the requirements of All-Union StateStandard (GOST) 7850-74 retains its quality for 15 days during the process of storage at 353 K under a nitrogen blanket containing no more than 1×10^–3% oxygen by wt.The duration of quality retention by caprolactam at 353 or 373 K is considerably reduced under a nitrogen blanket containing 6.7×10^–3% oxygen.The quality indices of caprolactam which have been made to conform to All-Union State Standard (GOST) 7850-74 canbe preserved only on the condition of storageat the minimum temperature which ensures keeping the caprolactam melted (T_cr=341.8 K) and in a medium of nitrogen containing no more than 1 × 10^–1% oxygen.Translated from Khimicheskie Volokna, No. 1, pp. 32–33, January–February, 1987.     

Copper-Containing Complexes — Effective Quality Stabilizers for Caprolactam

It was found that the copper-containing additive 2-MeBI + CuCl₂ + MgCl₂ stabilizes the quality of caprolactam most effectively when it is transported in the molten state. A probable mechanism of formation of a complex of the additive with caprolactam is proposed.__________Translated from Khimicheskie Volokna, No. 2, pp. 54–58, March–April, 2005.     

Use of a centrifugal-bubbling absorber to withdraw caprolactam samples

Conclusions The use of a centrifugal-bubbling absorber in the stage of sampling caprolactam discharges for analysis makes it possible to sharply reduce the time for sampling, and to increase the reliability of the information obtained because of more efficient dissolution of the caprolactam in the twisted stream of liquid, and also thanks to realization of the absorption process in a single absorber.When CBA are used, automation of sampling for control of harmful discharges and regulation of technological process parameters is considerably simplified.Translated from Khimicheskie Volokna, No. 1, pp. 38–39, January–February, 1989.     

A method of monitoring the uniformity of a material

Conclusions 1. A technical solution has been proposed for contactless monitoring of the electrical conductivity of materials on change in their aggregate state.2. A curve is given for the change in electrical conductivity of caprolactam during the process of its solidification in the temperature range 80-20°C, from which it is possible to estimate additionally the degree of purity of the caprolactam and to predict properties of the yarn.Barnaul'sk Automation OKB. Translated from Khimicheskie Volokna, No. 5, pp. 58–60, September–October, 1993.     

Chromatographic determination of the caprolactam content of wastewater and of air

Conclusions A chromatographic procedure has been developed for determining caprolactam concentration which is characterized by high sensitivity, selectivity, and simplicity in execution.The procedure can be used for daily sanitary chemical monitoring of wastewater and working zone air in the manufacture of polyamide fibres.Translated from Khimicheskie Volokna, No. 3, pp. 55–56, May–June, 1986.     

Biochemical oxidation of caprolactam-containing wastewater from the production of synthetic fibres

Conclusions The chemical mutagenesis method is recommended for use in local purification installations for cleaning up of caprolactam-containing wastewater.Use of this method permits one to carry out a biochemical clean-up of wastewater having a caprolactam content up to 600 mg/liter while increasing the oxidative power of the aeration tank by a factor of two.Translated from Khimicheskie Volokna, No. 6, p. 46, November–December, 1985.     

Regeneration of active carbons saturated with caprolactam

Low- and medium-temperature regeneration of active carbons saturated with caprolactam was investigated in regenerating medium (nitrogen, vapor–gas mixture) and without it. The optimum conditions of conducting the process were determined. The results of laboratory studies of thermal regeneration of active carbons were confirmed in experimental-industrial tests.All-Union Scientific-Research Institute of Synthetic Fibres, Tver'. Translated from Khimicheskie Volokna, No. 2, pp. 43–47, March–April, 1995.     

Enhancing the purification of cold water

Conclusions 1. The use of 0.40 mg/liter PAA enables clarification and decolouration of water to be enhanced during winter and clarified water of the required quality to be obtained.2. The increase of 1.9% in the cost of reagents when PAA is used is negligible compared with the effect obtained.Kiev Combine. Translated from Khimicheskie Volokna, No. 2, pp. 73–74, March–April, 1969.     

Use of alkali-containing secondary products in glass technology

The results of a study of the use of alkali-containing secondary products from production of caprolactam and ethylene for partial or total replacement of soda in production of electrotechnical and sheet glass are reported. Thermogravimetric, differential thermal, and x-ray phase analyses showed that replacing soda ash with alkali-containing secondary products intensifies glass-melting processes.Translated from Steklo i Keramika, Nos. 5–6, pp. 2–4, May–June, 1994.     

Selection of an indicator for the titrimetric determination of the weight proportion of benzoic acid in molten caprolactam

Conclusions The use of four different indicators has been investigated in the titrimetric determination of the weight proportion of benzoic acid in molten caprolactam.It has been shown that the phenolphthalein indicator which is used at present for benzoic acid analysis is not suitable. Tropeolin 000 may be recommended for use instead of it.Translated from Khimicheskie Volokna, No. 5, pp. 56–57, September–October, 1987.     

Reason for the luminescence of polycaproamide and caprolactam

Conclusions It is suggested that the luminescing structures in polycaproamide and in the corresponding monomer have a single nature.One of the products from decomposition of caprolactam -hydroperoxide has well-defined luminescence properties; some conditions for its formation have been investigated.The most probable reason for the luminescence is the appearance of -ketoimide groups in caprolactam and polycaproamide due to thermal oxidation.Translated from Khimicheskie Volokna, No. 5, pp. 30–31, September–October, 1985.     

Structure of the catalytically active compound in caprolactam polyamidation activated by the phosphoric acid-polyethylene glycol system

Conclusions Direct experimental proofs have been given for the formation of bis-(polyethylene glycol) phosphate — a catalytically active compound in the cationic polyamidation of caprolactam which is activated by the phosphoric acid-polyethylene glycol system.Translated from Khimicheskie Volokna, No. 4, pp. 14–16, July–August, 1988.     

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.     

The relationship between acidity of aluminas and their selectivity in the conversion of cyclohexanone oxime into caprolactam

A range of aluminas modified by addition of sodium, phosphate, sulphate, chloride and boria have been tested for the Beckmann rearrangement of cyclohexanone oxime to caprolactam in the temperature range 300–350 °C. A relationship was observed between the selectivity to caprolactam and the surface concentration of acidic sites of intermediate strength.     

Flow of caprolactam melt in spinneret holes

Conclusions A theoretical study of the flow of a caprolactam melt in a cylindrical channel has been made.Profiles of liquid velocity and pressure along the channel and transverse to it have been constructed, and the length of the hydrodynamic flow stabilization section has been determined.Translated from Khimicheski Volokna, No. 2, pp. 33–35, March–April, 1984.     

膜生物反应器处理己内酰胺生产废水

为了更加有效地提高己内酰胺生产废水生化处理装置抗高浓度废水冲击能力,在原A/O处理系统中采用膜生物反应器技术对己内酰胺生产废水进行生化处理。工业应用结果表明:由于己内酰胺废水中氨氮含量较高,膜生物反应器进水pH值应该控制在8.5～9.5,以保证系统有效的硝化反应,去除氨氮;当进水COD、氨氮的质量浓度分别控制在2 000、200 mg/L以内时,出水COD、氨氮的质量浓度分别小于70、15 mg/L。处理后的水质能够达到国家一级排放标准。     

Chromatographic determination of the oligomer content in aqueous solutions in caprolactam regeneration

Conclusions -- The qualitative and quantitative analysis for the content of oligomers in aqueous solutions in caprolactam regeneration may be carried out by the liquid-chromatography method after selective extraction of the monomer.-- The decisive role of compactness and of contact surface of the oligomer molecules in hydrophobic-dispersion interaction with chemically modified silica gel and in effect on retention time in the chromatographic system has been demonstrated.-- The proposed procedure is characterized by accuracy and reproducibility of the results and can be recommended for scientific and also for manufacturing purposes.Institute of Pneumatic Tires and Polyamide Fibres (Vidin, Bulgaria). Translated from Khimicheskie Volokna, No. 5, pp. 57–59, September–October, 1992.