The adsorption of pyrazolone acid dyes by polyamide fibres

Investigations of the adsorption of acid dyes (l–phenyl–3–methylpyrazolone derivatives) by polyamide fibres have been carried out. It has been found that the adsorption levels are unexpectedly different for various dyes. Some of the dyes, despite high concentration in the dyebath, show adsorption within the limits of what would be predicted by consideration of the amino group content in the amorphous region of the fibre. Other dyes, despite high pH, are characterised by considerably higher adsorption than would be predicted. The results obtained suggest that the increased adsorption of the dyes is brought about by the aggregation of molecules in the fibre into dimers or their multiples.     

Creep of aromatic polyamide fibres

Creep of Kevlar 29, Kevlar 49 and PRD 49-III fibres was investigated. The fibres exhibited transient creep and the strain-time relationship was represented by a logarithmic time law. The creep strain recovered with time when the load was removed. Upon reloading to the same creep stress the strain-time relationship was again logarithmic but the creep rate was reduced. Modulus measurements were made during the creep test and these showed that the modulus increased with time. This result indicated a crystallite rotation mechanism which could account for the experimentally observed creep strain. Creep in PRD 49-III fibres exhibited a small temperature dependence over the temperature range 20°C to 150°C. The apparent creep activation energy was consistent with the range of values reported for hydrogen bonding. This suggests one possible creep mechanism in which the combined action of stress and thermal activation causes rearrangement of intercrystalline bonds in the crystallite boundaries resulting in boundary creep. Boundary creep allows crystallite rotation which produces the macroscopic creep strain. Boundary creep is discussed in terms of the fibre morphology and a model of delayed elasticity.     

Surface modification of high-strength aromatic polyamide fibres

A modifying (finishing) composition for aromatic polyamide fibres which improves their properties in use was developed, extending the area of application of these fibres. The optimum composition of the finish was determined: an aqueous emulsion of oligoethyl hydride siloxane with SnCl ₂ catalyst. The finish is fixed and reacts with the fibre primarily in the surface layer, causing certain structural changes. Dedicated to the memory of Academician G. I. Kudryavtsev. Translated from Khimicheskie Volokna, No. 3, pp. 10–12, May–June, 1998.     

Preparation of polyamide fibres with antistatic properties

Conclusions It has been found that the ethoxylated phenols which are used as additives to PCA have antistatic properties. Increasing the content of ethoxy groups or the presence of an alkyl radical on the aromatic nucleus reduces their antistatic action.Ethoxylated phenols with a low ethoxy group content have an antistatic effect which is resistant to water treatment. With increase in ethoxy group content, the resistance of the polycaproamide to wet treatments is reduced, the presence of an alkyl radical on the aromatic ring increasing it.Some considerations have been advanced about the mechanism of action of the antistatic additives under study. A method is suggested for selecting them.Translated from Khimicheskie Volokna, No. 6, pp. 49–51, November–December, 1983.     

Diffusion of dyes in natural fibres

This review provides a summary of research on the penetration of dyes into natural fibres. Emphasis is placed on the relationship between diffusion and the structural morphology of the fibres. The types of commonly dyed natural fibres, the methods of measurement of diffusion and the data that have been collected by the use of each method are reviewed. The applicability of general theories of dyeing to natural fibres is also examined. Recent developments that have led to the direct observation of penetration pathways in wool fibres are described, together with the insights obtained into diffusion phenomena. Areas for future work are briefly indicated.     

Preparation and properties of fibres based on graft polyamide copolymers

Conclusions 1. Of the proposed methods of synthesizing graft polyamide copolymers, the use of peroxidized polycaproamide, activated by a metal of variable valence, and also radiation initiation of the graft polymerization reaction have found practical application.2. New fibres with improved hygienic, consumer, and special properties have been prepared, based on GPC.3. Effective methods of synthesizing GPC, in combination with the availability of technological equipment, have stimulated further development of the chemistry and technology of fibres from graft polyamide copolymers, which is interesting in the practical respect.Deceased.Translated from Khimicheskie Volokna, No. 4, pp. 9–14, July–August, 1984.     

Investigations of electrokinetic properties of dyed polyamide fibres

Changes of the electrokinetic flow intensity Q_v and the zeta potential for polyamide fibres colourless and dyed with Polan dyes were analyzed. Essential differences in determined quantities were found for fibres dyed with dyes of different steric structure.     

Birefringence of polyamide fibres of nonround cross-sectional from

Conclusions A method of determining the birefringence n of fibres having an uncomplicated profile (pentagonal, trilobal, or double rhombus) consists of the following: Over sections of the fibre one determines the ratio of the outer-contour dimensions — the diameterl of the fibre to its thickness d — the path over which the beam acquires the difference in speed ; the values of ,l, andl/d are averaged; and the calculation of n is carried out from the equation n = .This method has been tested on specimens of polyamide fibre prepared under identical melt flow rate conditions.Translated from Khimicheskie Volokna, No. 3, pp. 42–43, May–June, 1983.     

Adsorption of nonionic surface-active materials by polyamide fibres

Conclusions The possibility of using the polarographic method to investigate the adsorption of nonionic surface-active substances by the surface of polyamide fibres has been demonstrated.The differing adsorptive ability of the investigated NSAA is caused by their structure, the strength of the adsorbent-adsorbate chemical bond, orientation, and the form and length of the molecular chain.The results obtained may be used in the development of textile auxiliaries which will have a high adsorptive ability.Translated from Khimicheskie Volokna, No. 4, pp. 19–20, July–August, 1986.     

Thermooxidative decomposition of phosphorus and metal-containing polyamide fibres

Conclusions -- The thermooxidative decomposition of phosphorus and metal containing polycaproamide fibres prepared by introducing combustion retarders into the polymer melt has been studied.-- It has been found that the synergistic system MPA-AlO(OH), introduced into PCA, leads to the formation of coke-like residues which have a high resistance to oxidation. The coke-like residues obtained on thermolysis of PCA-DAMPA-AlO(OH) are enriched in phosphorus and nitrogen, which indicates a reaction of the flame-proofer with the degradation products of the PCA.Moscow State Textile Academy. Translated from Khimicheskie Volokna, No. 5, pp. 39–40, September–October, 1992.     

Model dyes for optimizing the dyeing of polyamide

Model disperse azo dyes, containing a salicylic moiety, hydrophobic alkyl chains and usual substituents, allowed the investigation of the effects of these structural variations on dyeing properties. By combining the results of both equilibrium and rate studies, some interesting structures for practical purposes could be identified.     

Sorption of azo dyes by polyamide chemisorption fibre

The possibility of capturing strong organic ions in azo dyes with amino-containing polycaproamide fibre was demonstrated. Some characteristics of extraction of azo dyes from model aqueous solutions were investigated. The effect of the pH of the external solution on the sorption activity of amino-containing polycaproamide fibre was established. The effect of steric factors of the structure of azo dyes on their chemisorption by the fibre was determined.Moscow State Textile Academy, Koloros Co., Moscow. Translated from Khimicheskie Volokna, No. 3, pp. 26–28, May–June, 1996.     

Dyeing properties of polyamide super-microfibre with disperse dyes

The dyeing properties of polyamide super-microfibres and conventional fibres dyed with disperse dyes have been studied by measuring the adsorption isotherm, the rate of dye uptake, the time of half-dyeing and the amount of equilibrium adsorption. The thermodynamic analysis shows that the adsorption isotherms of super-microfibres follow a Langmuir sorption model. The kinetic results show that super-microfibres have a faster dyeing rate and a higher equilibrium dye uptake compared to conventional fibres. This can be explained by the greater surface area and dye capacity of the super-microfibres. The wash and light fastness properties of the super-microfibres dyed with disperse dyes are lower than conventional fibres.     

Swelling of aromatic polyamide fibres in active media

Conclusions The method of swelling in active media, with the aid of optical microscopy, has been used to discover fine structural differences in aramide fibres. The method is informativeTranslated from Khimicheskie Volokna, No. 1, pp. 33–34, January–February, 1987.