Dyeing behaviour of cotton fabric bioscoured with pectate lyase and polygalacturonase

Bioscouring of cotton is normally carried out using pectinases having pectate lyase activity. The present study has examined the influence of pectate lyase and hydrolase on the surface of cotton fibre. Dye uptake by cotton scoured with polygalacturonase is found to be much lower than that scoured with pectate lyase, Pectate lyase gave better dye exhaustion at 90 °C. The difference in dye exhaustion after scouring with sodium hydroxide, polygalacturonase or pectate lyase, may be due to variation in the amount of surfactant retained by the fibre, as this hinders dye uptake. This was particularly the case with polygalacturonase. Reduced numbers of free carboxy groups on the fibre surface could indicate lower pectin content. On the other hand it could, however, be due to the esterification of carboxy groups in the pectin by hydroxy groups in the surfactant.     

Diffusion properties of reactive dyes into net modified cotton cellulose with triazine derivative

Cotton fabric is chemically modified with a 1,3,5‐triazine derivative containing multireactive and multicationic groups. The diffusion properties of the reactive dyes into net modified cotton cellulose are investigated. When the dyeing temperature is raised, the dye uptake increases gradually and approaches equilibrium after dyeing for 60 min. The diffusion coefficients at different temperatures and the activation energy of the dye are discussed. Compared with unmodified cellulose, the diffusion kinetics of the dye in the net modified cotton cellulose show significant changes. The activation energies of dyes in net modified cotton fibers are much lower than those of dyes in unmodified cotton. The dyeing behavior of the modified cotton is analyzed and compared with the unmodified cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2166–2171, 2007     

Dyeing of chemically modified celluloses. II. Effect of chemical modification of cellulose on the dyeing properties of some direct dyes

The behavior of partially acetylated cellulose, partially carboxymethylated cellulose, cyanoethylated cellulose, and cellulose grafted with polyacrylontrile toward three direct dyes, namely, Chlorantine Fast Red 6 BLL, Solophenyl Orange T4RL, and Diphenyl Brilliant Flavine 7GFF, was studied. Partially acetylated cellulose having 2.06% combined acetic acid showed higher dye uptake than the unmodified cellulose. The amount of dye uptake increased as the acetyl content increased up to 4% combined acetic acid. Beyond this, enhancement in the dye uptake was not significant. Whereas partially carboxymethylated cellulose showed a lower dye uptake than the control. The dye uptake decreased considerably as the carboxymethyl groups increased. The same holds true for cyanoethylated cellulose where increasing the cyanoethyl content caused a substantial reduction in the dye uptake. On the other hand, cellulose grafted with polyacrylonitrile up to 18.3% graft yield showed much higher dye uptake than the ungrafted cellulose.     

亚甲基蓝平衡吸附法评定棉织物生物酶精练果胶质去除效果

根据果胶质可吸附阳离子染料亚甲基蓝，平衡上染百分率能够间接表征棉纤维果胶质含量这一原理，采用亚甲基蓝平衡吸附法初步考察了棉织物生物酶精练对果胶质的去除效果。     

Photoinitiated graft copolymerization of hydroxyethyl methacrylate onto cotton cellulose

The photoinitiated graft copolymerization of hydroxyethyl methacrylate (HEMA) onto cotton cellulose was studied using uranyl nitrate (UN) and ceric ammonium nitrate (CAN) photoinitiators. Optimization of various parameters of the graft-copolymerization reaction viz., time, temperature, initiator, and monomer concentration, was carried out. The optimized conditions of grafting were employed to cotton samples swollen in zinc chloride as well as sodium hydroxide. Graft add-on was found to be dependent on the nature of substrate and the concentrations of monomer and photoinitiator. UN was found to be the better photoinitiator, giving higher grafting with HEMA. The grafted samples showed initially decrease and then marginal increase in the moisture regain with increase in graft add-on. The dye uptake of both direct and reactive dyes decreased with increase in graft add-on.     

Dyeing of chemically modified cellulose. IV. Dyeing of oxidized celluloses with some reactive and direct dyes

Oxidation of cotton cellulose with potassium periodate, potassium dichromate-sulfuric acid, and potassium dichromate-oxalic acid results in creation of variable amounts of acidic and reducing groups along the cellulose molecule, being dependent upon the type of oxidizing agent used. Such groups were found to have a profound effect on the acceptability of cellulose for reactive and direct dyes. The rate and extent of dye uptake for the oxidized celluloses were significantly lower than those of the unoxidized cellulose. While presence of the acidic groups in cellulose molecules induces a negative environment thereby making approach of the dye anions to the cellulose difficult, presence of the reducing groups lowers the magnitude of cellulose reactivity as well as decreasing its adsorptive power. Further modification of the oxidized celluloses via either borohydride or chlorous acid treatment brought about modified celluloses the dyeability of which confirms the inhibiting effect of the acidic and reducing groups of those oxidized celluloses on the rate and extent of dyeing with reactive and direct dyes.     

Reactive dyes for cellulose. Concurrent methoxide-hydroxide reactions of triazinyl reactive systems: a model system for assessment of potential fixation efficiency

A series of triazinyl reactive dyes, identical in all respects but for the leaving group, has been synthesised. The rate of hydrolysis of each member of the series, i.e. fluoro, chloro, sulpho and DABCO derivatives, has been determined. The corresponding nicotinic acid compound could not be included in the study as it did not yield the expected hydroxytriazine in dilute sodium carbonate solution. Each dye has been added, in turn, to a methanol-water solution in the presence of base and the chemical selectivity to methoxide attack determined from the product ratio. Measurements were made at 40°C and under conditions of equal reactivity to hydroxide ion, as determined from Arrhenius plots. The selectivity results are in agreement with empirical observations, made over more than 30 years, for the fixation efficiency to cellulose of dyes carrying these reactive groups.     

Reactive dye dyeability of cellulose fibers with cellulase treatment

Reactive dye dyeing was performed on cellulose fibers in combination with cellulase treatment. First, polynosic and cupra fibers were selected to discuss the saturation dye uptake of the previously cellulase-treated fibers. Cupra fiber exhibited a similar saturation dyeuptake dependence on weight loss, irrespective of dye species and the substantivity of the dyes. In the polynosic fiber, the saturation dye-uptake dependence on weight loss exhibited a minimum using a lower substantive dye and a maximum using a higher substantive dye. Comparative discussions of the saturation dye uptake based on X-ray and infrared measurements led to the assumption that a region dyeable with the higher substantive dye is created by the cellulase treatment of the polynosic fiber. This region is assumed to have some degree of order as shown by infrared spectroscopy. Next, cotton fiber, which is important from a practical viewpoint, is dyed and then hydrolyzed. It was found that the hydrolysis of cotton fiber dyed with a reactive monofunctional dye was retarded almost in the same manner as that dyed with Congo Red. The hydrolysis of cotton fiber dyed with dyes of higher substantivity and more bifunctional property was probably retarded to a greater extent compared to dyes of lower substantivity and less bifunctional property. © 1996 John Wiley & Sons, Inc.     

Reversible crosslinking in cellulose. I. Determination of mercaptan and disulfide in modified cotton

Mercaptan and disulfide contents of modified cotton fabrics could be determined by application of Leach's polarographic method for wool, with minor modification. It was found that mercaptocellulose prepared by the reaction of tosyl cellulose and potassium thiolacetate followed by alkaline hydrolysis contained considerable amounts of disulfided in addition to mercaptain. Iodometric titration of mercaptocellulose gave a higher value of mercaptan than that obtained by the polarographic method. The mercaptan and disulfide contents and methylene blue uptake of the iodine-treated samples indicate that some of the mercaptan groups further undergo oxidation to acidic groups as a result of the iodine treatment. The spatial effect in the oxidation of mercapto groups in modified cotton is briefly discussed.     

Synthesis of reactive dyes based on the bis-(N-carboxymethylamino)monoquaternary-triazine-bis-ethylsulphone reactive group. Part 1: Application to cotton cellulose

Reactive dyes containing the bis-( N -carboxymethylamino)monoquaternary-triazine-bis-ethylsulphone [bis-( N -CMA)-MQT-bis-ES] group and related derivatives have been synthesised. When boiled under mildly acidic conditions, such dyes are able to form two small vinylsulphone dye molecules through a process of 1,2-trans elimination. The bis-( N -CMA)-MQT-bis-ES dye was applied using different dyeing procedures (novel dyeing methods 1 and 2). The dyeing and soaping-off results of bis-( N -CMA)-MQT-bis-ES dye were compared with a model sulphatoethylsulphone dye applied using the conventional alkaline fixation method used for applying this type of reactive dye to cotton. The bis-( N -CMA)-MQT-bis-ES dye showed higher exhaustion and fixation values applied using novel dyeing method 2 compared with the sulphatoethylsulphone dye applied using the alkaline fixation method. The soaping-off efficiency for the large bis-( N -CMA)-MQT-bis-ES dye applied using novel dyeing method 2 was the same as that obtained for the sulphatoethylsulphone dye applied using the alkaline fixation method.     

Dielectric and infrared study of some cellulose derivatives

Measurements of the dielectric constant of cotton cellulose, mercerized cellulose acetate, methyl cellulose, and carboxymethyl cellulose have been carried out in the temperature range of 0–70°C at different frequencies. The results showed that the values of the dielectric constant, with all cellulose derivatives at a given frequency, are greater than that of cotton cellulose and lower than that of mercerized cellulose. The variation of the dielectric constant with temperature showed a transition at 30–40°C with all the samples studied. These results, together with those from infrared spectra and specific volume measurements, indicated that the dielectric behavior depends greatly on the nature of the side group, the degree of hydrogen bonding between the different chains, and the micropores present in the fiber.     

An analysis of the factors influencing unlevelness of a direct dye on a pilot-scale jet dyeing machine

The investigation used a pilot-scale jet dyeing machine to examine the relationship between the dye exhaustion rate per contact and dye unlevelness on the fabric. It was found that a commercially acceptable degree of unlevelness could be obtained for a direct dye on pure cotton fabric as long as the exhaustion rate did not exceed 1.0% per contact, independent of the dye amount used. Bath contacts and fabric contacts influenced unlevelness in equal manner. Non-ionic surfactants, which had been selected so as not to influence the dye exhaustion rate or its equilibrium uptake, appeared to have little or no influence on unlevelness. Control of the dye uptake by electrolyte addition proved to be a more efficient dyeing strategy than controlling it by dye addition, as unlevelness in the first case was much lower at the same exhaustion rate.     

Levelling properties of some reactive dyes on cellulose

The levelling properties of nine reactive dyes containing one or two sulphatoethylsulphone reactive groups or one sulphatoethylsulphone and one monochlorotriazine reactive groups have been investigated. A novel test method specifically applicable to reactive dyes has been used in order to evaluate levelling. Undyed and dyed cotton samples were simultaneously dyed in the same bath and the fractions of the additional dye fixed on each of the cotton samples were determined afterwards. A dye distribution index has been proposed that predicts reactive dye levelling according to whether the index exceeds 50% or not. The index was found to depend not only on the nature of the dyes, but also on the concentration of the dye fixed on cotton, the dyeing temperature and the salt concentration in the dye liquor. In redyeing tests the degrees of primary and secondary exhaustion and of dye fixation were measured as a function of concentration of the dye fixed on cotton. Finally a satisfactory correlation was found between the index and the classical inorganicity/organicity value of the dyes. The results also suggest that the levelling properties depend on the degree of dye aggregation.     

Salt-free dyeing of cotton cellulose with a model cationic reactive dye

A model cationic reactive dye based on an anthraquinone chromophore was prepared. The synthesis of this dye was achieved by the modification of the a free amino group of an anthraquinone-based dye, reacting first with cyanuric chloride and then with N -(2-aminoethyl)pyridinium chloride. TLC analysis was employed to follow the chemical reactions. The application of the prepared dye to cotton fabric was carried out using the exhaustion method without the addition of electrolytes. The results showed that, despite no electrolytes being present in the dye bath, a high percentage of dye exhaustion could be obtained. The high percentage of dye exhaustion was attributed to the attractive force between positive charges on the dye molecule and the negatively charged fibre surface. A high degree of dye fixation with excellent wash fastness was also achievable. Advantageously, it was found that this cationic reactive dye showed promising fastness to light when compared with that of analogous conventional basic dye on cotton. It is believed that the pyridinium cationic moiety, which attached separately to the chromophore via aliphatic spacer groups, was later eliminated during the washing-off process, hence causing an insignificant effect on the photofading of the dyed fabric.     

Dyeing of chemically modified cellulose. VII. Dyeability of cellulose bearing aromatic amino,nitro, and acrylamidomethyl groups

The effect of introducing aromatic amino, nitro, and acrylamidomethyl groups in the cellulose molecules on the dyeing properties of two direct dyes (Chlorantine Fast Red 6BLL and Solophenyl Orange T4RL) as well as two reactive dyes, (Procion Brilliant Red M5B and Procion Brilliant Orange MG) was investigated. The extent and rate of dyeing for cellulose bearing aromatic amino groups were lower than those of nonmodified cellulose irrespective of the dye used. In addition, the extent of dyeing decreased as the amount of aromatic amino groups increased. The opposite held true for cellulose bearing acrylamidomethyl groups, particularly with direct dyes where increasing these groups caused a substantial enhancement in the dye uptake. On the other hand, subjecting cellulose to nitration reaction prior to dyeing diminished significantly its dyeability with the dyes.     

Ultraviolet-radiation-induced graft copolymerization of styrene and acrylonitrile onto cotton cellulose

Photoinitiated graft copolymerization of the vinyl monomers, styrene and acrylonitrile, onto cotton cellulose was studied using uranyl nitrate and ceric ammonium nitrate as photoinitiators. Uranyl nitrate photoinitiation showed a higher level of grafting for styrene, whereas in the case of acrylonitrile ceric ammonium nitrate was found to be the better photoinitiator. Optimized conditions of grafting, when employed to cotton swollen with sodium hydroxide and zinc chloride, enhanced the graft levels for both monomers. Grafted samples were subjected to thermal analysis, as well as estimation of moisture regain and tenacity. Thermal stability increased, whereas, the moisture regain and tenacity decreased, with the increase in graft add-on in the case of both monomers. Acrylonitrile-grafted cotton showed dyeability with cationic dye that improved with the level of graft add-on. Possible explanations have been given.     

Effect of solvent induced hydroxylation of cyanoethyl group on dye uptake of cotton fabrics

The present investigation deals with the dyeing behavior of solvent induced cyanoethylated cotton fabric. The modified cotton fabric was dyed by conventional method with commercial reactive dye (Drimarene Red). It is observed that acetone induced cyanoethylated samples exhibit higher color values than ethanol treated samples. The effect of nitrogen content on the dye uptake of modified fabric is assessed which shows a good correlation between them. It is obvious that crystallinity has a noticeable effect on the dye uptake of both solvent modified fabrics. For convenience and comparison, a set of samples are also dyed without addition of salt, alkali, and both. It is evident that even without addition of salt, alkali and both the samples exhibit a significant dye uptake. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

直接染料对甲壳胺纤维的染色性能

探讨了中性盐、温度、染料用量对甲壳胺纤维直接染料染色性能的影响，比较了脱脂棉和甲壳胺纤维的染色性能。实验结果表明：中性盐对染料的影响与染料的磺酸基的数目有关，对4～6个磺酸基，中性盐起促染作用．对双磺酸基，起缓染作用：而在70℃时染色的上染速度明显快于40℃，染料浓度在2％时几乎尽染，当上升到8％时上染率仍在70％以上；甲壳胺纤维的上染速度和上染率明显高于棉，其可染性、染色速度、表观染色深度远高于棉易产生染色不匀现象。     

Faserstruktur und Färbeeigenschaften von Cellulosefasern, 1. Zusammenhänge zwischen Veränderungen der Faserstruktur und der Farbstoffadsorption bei Baumwolle durch Mercerisation und Flüssigammoniak-Behandlungen

Changes of fiber structure and the adsorption of direct dyes in cotton subjected to different kinds of mercerisation and liquid ammonia treatment have been studied. Therefrom a new general relationship between dye adsorption and fiber structure of cellulosic fibres has been given as a result. The fiber structure in the water swollen state was characterized by measurements of specific pore volume, specific pore surface and pore size distribution. The dyeing behaviour of the different treated cotton was determined by adsorption isotherms. The results revealed that for equilibrium dye adsorption from aqueous solution a transitional pore region with pore diameters of 20–60 Å has a special importance. Changes of these pores by the different swelling treatments correlated directly with the dye uptake. This pore region is found in cotton between the elementary fibrils.     

Dyeing of cotton fibers decrystallized by alkali swelling and partial substitution

This report summarizes the observations made on the dyeing behavior of highly decrystallized cotton fibers obtained by partial acethylation and cyanoethylation of NaOH swollen fibers. The dyeing studies were also carried out after crosslinking these decrystallized samples. A purified direct dyeing Chlorazol Sky-Blue FF, has been used for the studies. It is observed that partially cyanoethylated and acetylated celluloses show a dye uptake of more than twice that of the corresponding swollen controls even for low degrees of substitution such as about 5.0% acetyl content for the acetylated fibers and 1.0% nitrogen content for the cyanoethylated fiber. On crosslinking also the trend in the dye uptake pattern remained the same, thought the actual amount of dye the fibers could adsorb was markedly reduced. The swollen, substituted, and crosslinked fibers showed a better uniformity of appearance than the swollen and crosslinked fibers.