Surface characterization of low temperature plasma treated wool fiber

Previous investigation results revealed that after the Low Temperature Plasma (LTP) treatment, the hydrophilicity of wool fiber was improved significantly. Such improvement enhances the wool dyeing and finishing processes which might be due to the changes of the wool surface to a more reactive one. In this paper, wool fibers were treated with LTP with different gases, namely, oxygen, nitrogen and gas mixture (25 % hydrogen/75 % nitrogen). Investigations showed that chemical composition of wool fiber surface varied differently with the different plasma gas used. The surface chemical composition of the different LTP-treated wool fibers was evaluated with different characterization methods, namely FTIR-ATR, XPS and saturated adsorption value. The experimental results were thoroughly discussed.     

Effect of low temperature plasma treatment on wool fabric properties

Low temperature plasma (LTP) treatment was applied to wool fabric with the use of a non-polymerizing gas, namely oxygen. After the LTP treatment, the fabric properties including low-stress mechanical properties, air permeability and thermal properties, were evaluated. The low-stress mechanical properties were evaluated by means of Kawabata Evaluation System Fabric (KES-F) revealing that the tensile, shearing, bending, compression and surface properties were altered after the LTP treatment. The changes in these properties are believed to be related closely to the inter-fiber and inter-yarn frictional force induced by the LTP. The decrease in the air permeability of the LTP-treated wool fabric was found to be probably due to the plasma action effect on increasing in the fabric thickness and a change in fabric surface morphology. The change in the thermal properties of the LTP-treated wool fabric was in good agreement with the above findings and can be attributed to the amount of air trapped between the yarns and fibers. This study suggested that the LTP treatment can influence the final properties of the wool fabric.     

Dual-mode adsorption of cochineal natural dye on wool fibers: Kinetic,equilibrium, and thermodynamic studies

The dual-mode adsorption model was used to investigate the adsorption behavior of cochineal natural dye on wool fibers. Kinetic, thermodynamic, and equilibrium characteristics were investigated in terms of the adsorption isotherm, affinity, enthalpy and entropy changes, dyeing rate, diffusion coefficient, and activation energy of dye diffusion. The results revealed the prominent role of dyeing pH in determination of dyeing mechanism and dye adsorption isotherm type. At pH 4, dual Langmuir-Nernst model with the highest correlation coefficient was found as the most appropriate isotherm model to describe the adsorption behavior of cochineal onto wool fibers while at pH 6, the adsorption isotherm was the Nernst type. Cochineal adsorption onto wool was exothermic which resulted in progressive fall in affinity and equilibrium dye up-take values with increasing temperature. Moreover, dyeing rate steadily increased with temperature. At pH 4, affinity, dyeing rate, and diffusion coefficient demonstrated higher values compared to pH 6 whereas enthalpy and entropy changes, and activation energy showed lower values. Additionally, negative value for activation energy was obtained at pH 6. The results are deliberated based on the different possible interactions between cochineal dye and wool fiber.     

Dyeing behavior of laser-treated polyester

Polyester fabric was pre-treated with laser, followed by dyeing. The experimental results revealed that the rate of dyeing was greatly increased but the final percentage of dye exhaustion at equilibrium did not show any significant change. Based on the thermodynamic parameter of dyeing, it was concluded that laser treatment could provide the possibility of developing a low temperature dyeing process. Morphological and thermal studies revealed that obvious surface structure changes occurred. In the morphological analysis, ripple-like structure was found after laser treatment. This ripple-like structure may have captured more dye particles which could improve the dyeing behavior of polyester fibre. On the other hand, thermal analysis result revealed that the surface of polyester becomes highly amorphous on laser treatment, due to ablation. Meanwhile, XPS analysis showed that hydrophilic functional groups were introduced on to the laser-treated polyester fibre surface. As a result, surface physical and chemical changes induced by laser affect the dyeing behavior of polyester fibre. However, the laser treatment could not impart any adverse effect on color fastness to crocking and washing.     

Transglutaminase treatment for improving wool fabric properties

The microbial transglutaminase (mTGase) is used as a bio-catalyst to repair the wool damages caused by chemical or enzymatic treatments. In this paper, the effect of mTGase on the degree of yarn strength, area shrinkage, wettability, and the dyeing properties of wool was investigated. Through mTGase treatment, the yarn strength was improved about 22.2 %. The knitted wool fabrics treated with mTGase after pretreatment of H₂O₂ and protease displayed 7.5 % of area shrinkage and about 22.3 % recovery in tensile strength when compared with those treated without mTGase. Also, mTGase treatment could improve the wettability and dyeing properties of wool fabrics. With the increase of mTGase concentration, the initial dye exhaustion increased significantly and the time to reach the dyeing equilibrium was shortened. It was evident that the improvement of dyeing properties was closely related to the improvement of wettability performance of wool fabric by using transglutaminase.     

Dyeing properties of nylon 66 nano fiber with high molecular mass acid dyes

Research and development of nano fiber products is very active over the world. Physical characteristics and dyeing properties of nylon 66 nano fiber were investigated in this study. X-ray diffraction, DSC, analysis of amino end group, and water absorption were performed to get information concerning physical properties of nano fiber. Nylon 66 nano fiber was dyed with high molecular mass acid dyes. Effects of dyeing temperature, pH of dyeing solution, and concentration of acid dyes on dyeing properties such as rate of dyeing and the extent of exhaustion, were examined and compared to those of regular fiber. It was found that nano fiber adsorbed acid dyes at lower temperature, got rapidly dyed, and its extents of exhaustion at specific dyeing temperature were higher than regular fiber. It was also observed that nano fiber could adsorb a large amount of acid dye without a significant loss in the extent of exhaustion. Washing fastness of the dyed nano fiber was lower by 1/2∼1 grade, light fastness by 1 grade than the dyed regular fiber.     

Effect of Dye Solution Ionic Strength on Dyeing of Cotton with Reactive Dyes

The controlling effect for dye exhaustion (adsorption) and diffusion (absorption) in a reactive dyeing of cotton is shown to be exerted by ionic strength in the dye solution rather than concentration of inorganic salts used as electrolytes. The study showed that the conclusion applies to both exhaust dyeing for dye exhaustion and pad dyeings for dye diffusion. Further, the addition of an alkali, even though it is not used as an electrolyte, increased the extent of exhaustion (in exhaust dyeing) and diffusion (in pad dyeing) due to increase in ionic strength of the dye solution. Hence, the total ionic strength of reactive dye solution for dye exhaustion and diffusion must be taken into account in order to ensure optimum reproducibility. Means for determining the total ionic strength of exhaust or pad dye solutions for different electrolytes are given.     

Selective control of polyamide dyeing with acid dyes using hydroxypropyl-β-cyclodextrin

The effect of hydroxypropyl-β-cyclodextrin (HPβCD) in the dyeing of polyamide fabric was investigated under conditions that mimic industrial dyebaths where dye mixtures are used. The dyes used were Telon Red BN, Telon Yellow A-2R, and Telon Blue RR. The blue dye complexed with HPβCD whereas the other dyes did not do so under the conditions used. The dyeing results were compared with those obtained using a traditional retarding agent, Albegal B. The exhaustion dyeing data showed that HPβCD mainly affected the dyeing behavior of the blue dye that became encapsulated. In the case of the yellow and red dyes, changes in the overall kinetics of dyeing were observed, resulting in modified exhaustion profiles. In comparison, Albegal B retarded the blue dyeing process and increased the rate of exhaustion of the yellow dye while the exhaustion curve of red dye remained unchanged. The color uniformity of the dyed polyamide was improved when HPβCD was used. This resulted from the more controlled exhaustion rate during the critical phase of the dyeing process.     

Effect of enzymatic treatment on the dyeing properties of protein wool fibers

Two proteolytic enzymes were used as auxiliaries in the dyeing of wool fabrics with acid dyes. The effect of the enzymes on dye exhaustion (%E) and dye uptake (K/S) was studied at 70, 85, and 98 °C and compared to the corresponding values obtained for the control samples which were dyed without enzymes under the same conditions. Two commercially available dyeing auxiliaries commonly used for the dyeing of wool at low temperatures were also used under the same conditions and compared with the dyeings made with and without enzymes. Treatment with transglutaminase was done in order to compensate the damaging effects of protease. The study shows that the enzymes could be used as auxiliaries in the dyeing of wool at lower temperatures.     

Preparing fluorescent wool/acrylic blends with a hemicyanine reactive cationic dye

Wool/acrylic blends were dyed with a hemicyanine reactive cationic dye, Dye 1, to prepare the fluorescent wool/acrylic blends in this article. The study initially focuses on the optical properties of Dye 1, followed by dyeing properties of Dye 1, then ended with fluorescent properties of the dyed wool/acrylic blends. The results show that the exhaustion, fixation, and fastness to washing and rubbing of Dye 1 on wool, acrylic, and wool/acrylic blend were good throughout. The dyed wool/acrylic blends can emit obvious fluorescence. In addition, according to the EN-1150 standard (1999), the chromaticity of dyed wool/acrylic blends meet the requirements of fluorescent pink when the dye concentrations are suitable.     

Dyeing properties of mixture of ultrafine nylon and polyurethane with different types of dye

The dyeing and color fastness properties of levelling type acid dye, milling type acid dye, metal complex dye and reactive dye on ultrafine nylon, polyurethane fiber/film and their mixtures were investigated. Ultrafine nylon was dyed well with four types of dye at pH 3-6, but levelling type acid dye showed low washing fastness. Amine-rich polyurethane fiber exhibited enhanced dyeability due to amino groups which acted as dyeing sites, compared to regular polyurethane fiber. In simultaneous dyeing with milling type acid dye and metal complex dye, amine-rich polyurethane fiber absorbed more dye molecules than ultrafine nylon, the color difference between two fibers were apparent. Polyurethane-impregnated ultrafine nylon was also prepared and its build-up properties were determined. It was found that polyurethane whose soft segment was composed of polytetramethylene glycol (PTMG) and polypropylene glycol (PPG) showed improved dyeing property and subsequently high color strength.     

Application of liquid organic salt to cotton dyeing process with reactive dyes

Reactive dyes are used widely in cotton dyeing process. Reactive dyeing uses high amounts of inorganic salts to accelerate dye exhaustion. These salts are then discharged to the effluent, leading to serious environmental problems. Biodegradable organic salts can alternatively be used in the dyeing process. In this paper, a new liquid organic salt was synthesized by acid-base neutralization, which was used to replace inorganic salts in reactive dyeing. Dye exhaustion in organic salt dyeing was similar to the values in conventional dyeing. However, dye fixations were slightly lower in organic salt dyeing than in conventional dyeing. The washing fastness of dyed fabrics with organic salt was excellent. Experimental results showed that dye exhaustion reached the maximum value when the concentration range of organic salt was from 20 g/l to 40 g/l. In addition, the optimal alkali concentration in organic salt dyeing was found to be about 30 g/l. These parameters suggested organic salt could replace inorganic salt in reactive dyeing process.     

UV-grafting coloration of cotton and wool fabrics using bismethacrylated quinizarin dye

A novel bifunctional quinizarin dye possessing two photoactive methacrylate groups was synthesized by the reaction of quinizarin with methacryloyl chloride. The synthesized dye, a low substantive dye under the conventional dyeing process, can be photografted onto cotton and wool fabrics at room temperature without neutral salts, which makes it a novel coloration process of excellent environmental friendliness. The concurrent polymerization and grafting of the synthesized dye onto cotton or wool can be assisted by a photoinitiator and acrylic acid in the case of cotton grafting. Moreover, color yields of the grafted fabrics improved significantly with the photografting of the bifunctional dye. The bifunctional dye can be photopolymerized with the increase in UV energy to 25 J/cm² and the oligomeric dye has a degree of polymerization of 5 or more. Furthermore, the color fastness properties of the grafted fabrics were superior to those of the dyed fabrics via exhaustion.     

Combined use of cationization and mercerization as pretreatment for the deep dyeing of ramie fibre

In order to produce deep shades of colour, ramie fibre was subjected to pretreatment by cationization, caustic mercerization (slack and tension condition), and liquid ammonia mercerization. The untreated and pretreated samples were dyed with 0.5 to 7 % concentrations (on mass of fiber (o.m.f)) of Liyuansol Red FL-2BL reactive dye. The dyeing properties of dye exhaustion, fixation, colour uniformity, wash fastness, and rubbing fastness were investigated. The results indicated that these pretreatments improved dye exhaustion and fixation on ramie fibre, with no loss of fastness. For the untreated and treated substance, the amount of dye mass absorption increased linearly with increased dye o.m.f. Cationic treatment improved performance, with 89 % and 98 % for exhaustion and fixation, respectively, and the maximum K/S values of all fibers receiving pretreatment. The colour uniformity was acceptable and similar for the untreated and treated ramie fibers, with the exception of cationic-treated fabric dyed at 7 % dye o.m.f that showed a high standard deviation value of colour uniformity. The Freundlich and Langmuir adsorption isotherm models were also used to study the adsorption of dye on ramie fibre; all of the adsorption processes fit the Freundlich model.     

Colorimetric studies of benzoquinoline based hot brand monoazo reactive dyes and their dyeing performance on various fibers

A series of hot brand monoazo reactive dyes (9a-l) were obtained by the coupling of diazotized 1Hbenzo[ g]pyrazolo[3,4-b]quinoline-3-ylamine (5) with various cyanurated coupling components (8a-l) in good yield. Synthesized dyes were characterized by various spectroscopic techniques. Their dyeing performances as reactive dyes have been assessed on silk, wool, and cotton fabrics. The percentage dye bath exhaustion and fixation on different fibers were found to be very good. The dyed fabric showed moderate to very good light fastness and good to excellent washing and rubbing fastness properties. Spectral properties and colorimetric data of synthesized dyes have also been studied in detail.     

Influence of water hardness on acid dyeing with silk

In this paper, the effect of water hardness, expressed in CaCO₃ equivalent, on the dyeing silk with acid dye under acid, alkaline and isoelectric point dyeing conditions was studied by zeta potential method. Under acid condition and in the presence of calcium ion, the positive zeta potential of silk was found to decrease with a reduction in the dye adsorption. Such a phenomenon might be due to the presence of cation which increased the dyeing potential barrier at the interface between fibre and dye solution. This would result in a higher resistance of dye anions passing through the interface. Under alkaline condition, the zeta potential on silk was negative and resulted in a strong potential barrier for the dye anions. The presence of calcium ion would result in a decrease in the absolute value of zeta potential of silk fibre with an overall increase in dye absorption. Under isoelectric point, the zeta potential of silk fibre was found to be near zero and dye adsorption was not influenced by the cations. When studying the effect of calcium ion on the silk dyeing with acid dye under acid, alkaline and isoelectric point dyeing conditions, it was found that calcium ions influenced dye exhaustion and fixation greatly under acidic and alkaline dyeing conditions, which such influence became much smaller when the pH of dyebath was at the isoelectric point of the fibre. These results showed that calcium ion could produce strong electrolytic effect on dyeing even under very low concentrations.     

New thiol-disulfide exchangers as anti-setting agents for wool fabric during dyeing

Setting of wool fabrics during dyeing is an acute industrial dilemma facing most of wool dyers. Therefore, wool fabrics were dyed with acid, basic, as well as mono- and bi-functional reactive dyes in the presence of selected aliphatic and aromatic anti-setting agents; namely 3,3-dithiodipropionic acid (DTDPA), dithiodiglycolic acid (DTDGA), 5,5-dithio-bis(2-nitrobenzoic acid) (DTBNBA), dithiodibutyric acid (DTDBA), 2,2-dithiodisalicylic acid (DTDSA), and 6,6-dithiodinicotinic acid (DTDNA). The effect of incorporating the said thiol/disulfide-exchangers into the dyeing bath of wool on its dimensional stability was assessed. The influence of the proposed anti-setting agents on the dyeability of wool with the said reactive dyes was monitored. The alteration in the chemical composition of the dyed fabrics was monitored by determining their sulfur and nitrogen contents, cysteine content, and the solubility degree in alkaline solution. The used reagents were found to be effective in stabilization of wool during dyeing with reactive dyes to different extents depending on the nature of the used anti-setting agent. Limited change in the chemical composition of the dyed samples was monitored without affecting their dyeability with the said dyes. The mechanism of interaction of these reagents with wool fabrics during dyeing was proposed.     

A new method for brightening wool in a dye bath

A new method for brightening wool during dyeing has been developed using tert-butylamine borane in the dyebath. The method was found to be significantly superior to current industrial practice using hydroxylammonium sulphate or its derivatives. The effects of tert-butylamine borane on dye shades and dyeing quality have also been assessed with a range of commercial wool dyes. The results of this study have shown that the new method is effective in preventing hydrothermal wool yellowing during dyeing, and can produce brighter shades of dyeings without significantly altering the dye shades or impairing the dyeing fastness and mechanical properties of the dyed wool under the conditions examined. The advantages of the concurrent bleaching and dyeing method over conventional bleaching and dyeing processes include reduced processing time, improved energy efficiency, and lower water consumption, arising from reduction in the number of fiber treatment steps.     

Effect of chelating agent in disperse dye dyeing on polyester fabric

In this study, mild acid based chelating agents (glycolic acid, gluconic acid, ethylenediaminetetraacetic acid, and citric acid) were used for the dyeing of polyester fabrics with metal sensitive disperse dye in closed dyeing process. The chelating and pH adjustment efficiencies were compared in disperse dyeing condition. In the comparative analysis with different chelating agents, glycolic acid showed a higher chelation efficiency and consequently showed higher dye bath exhaustion and color strength. Slight differences in the color fastness of the dyed samples obtained by employing four different chelating agents were observed.     

Effect of using cold plasma on dyeing properties of polypropylene fabrics

The low temperature plasma (LTP) technique is used widely to modify polymer and textile materials. This paper describes the development of a plasma system for textile treatment. Polypropylene (PP) has a very low value of the surface free energy (approximately 20–25 mJ/m²). Due to low surface energy, Polypropylene has very weak hydrophilic properties. By controlling the plasma variables, such as the nature of gas, the discharge power, the pressure and the exposure time, a great variety of surface effects can be generated. In this paper, we report the effect of cold plasma of O₂ and N₂ gases at various time of exposure on the dyeing and physical properties of PP fabrics. The results show a significant increase in the color depth upon dyeing after treating PP fabrics with low temperature plasma of O₂ and N₂. For comparing the amount of fabrics dye exhaustion, we have used reflective spectrophotometer. The morphology of the modified surfaces has also been investigated using scanning electron microscopy (SEM). And also FTIR was used to examine the functional groups of the corresponding samples.