UV-induced coloration of cotton fabrics by photografting of acrylamido dyes using acrylamide as a comonomer

Formulations of acrylamido dyes containing comonomers can be photografted onto cotton fabric upon UV irradiation at room temperature without neutral salts, which makes it a novel coloration process of excellent environmental friendliness. The photografting of the dyes can be assisted by the copolymerization of the acrylamide comonomer which may reduce the steric hindrance of the bulky dyes. About 90 % of the dyes and 94 % of the acrylamide are photopolymerized in the solution and the degree of polymerization is estimated to be 13.2 according to ¹H-NMR and MALDI-TOF mass analyses. The optimal K/S values of the grafted cotton fabrics showed 13.3 and 12.3 for red and yellow dyes, respectively. The optimal UV-grafting coloration can be achieved when a UV energy of 25 J/cm² was irradiated on the padded fabrics with a formulation of 0.65 mole ratio of acrylamide to the dyes, 7 wt% acetophenone photoinitiator (Irgacure 2959) based on the dye weight under pH 6. Furthermore, the color fastness properties of the grafted fabric were superior to those of conventional reactive dyeing of the dyes due to higher molecular weight of the polymerized dyes.     

LED-UV grafting of vinylsulfone dyes onto photo-oxidized wool fabrics

Photografting coloration of wool was carried out under UV-LED irradiation at room temperature using aqueous vinylsulfone dye solution containing vinylsulfonic acid as a comonomer. UV-LED irradiation of the 395 nm emission is more energy efficient, less damaging to the dyes, and much safer to human eyes compared with polychromatic mercury UV lamps. However, in case of the UV-LED lamps, the wool needs to be photo-oxidized either by UV/ozone or polychromatic UV irradiation before the dye photografting. The surface treatments increased the sulfur and oxygen contents in the modified wool surfaces. While the optimally photografted wool fabrics under the UV-LED lamp yielded a K/S value of 9.9, the K/S of the grafted wool increased to 25.2 and 13.6 after the UV/Ozone or polychromatic UV preoxidation at UV energies of 10.6 J/cm² and 25 J/cm² respectively. The color fastness properties of the photografted fabrics were far better than with those of the conventionally reactive-dyed fabrics, implying that the high-molecular-weight photografted dyes seemed to be more durable than the low-molecular dyes.     

Continuous photografting of HEMA onto polypropylene fabrics with benzophenone Photoinitiator

Continuous photografting onto polypropylene fabrics in the absence of inert gases was carried out to improve hydrophilic property of PP fabrics, which was padded with a formulated solution of 2-hydroxyethyl methacrylate(HEMA) and benzophenone as a monomer and a photoinitiator, respectively. The grafting yield increased with increases in benzophenone concentration up to 30 % on the weight of the monomer and UV energy up to of 38 J/cm², while 30 % HEMA concentration was optimal for the grafting efficiency. The physicochemical properties of the grafted PP fabrics were monitored by FT-IR, SEM, zeta potential, and dyeability to a cationic dye. The grafting increased O_1s/C_1s content and remarkably produced more negative zeta potentials compared with the pristine PP fabric. Also the grafted PP showed the increased dyeability to cationic dyes with increasing graft yield resulting from the enhanced electrostatic interaction between the dyes and negatively charged surface of the grafted PP fiber. In addition, improved hydrophilic property of grafted PP fabrics was ascertained by more rapid water wetting time and higher water absorbency.     

Study on the dyeing of wool fabrics with Phytolacca berry natural dyes

Dyeing of wool fabrics with natural dyes from Phytolacca berries has been studied. The effect of dye concentration, dye bath pH, dyeing time and temperature were discussed. The influence of chitosan application on the dyeing properties of wool fabrics was investigated. The SEM photographs of chitosan treated wool fabrics clearly depict the deposition of chitosan on the fibers. The effect of chitosan concentration, dye bath pH, dyeing time and temperature has been studied by orthogonal experiment. It has been proved that the dyed wool samples pretreated by chitosan have higher color fastness, faster dyeing rate, and better antibacterial properties compared with untreated ones.     

Ultrasound assisted extraction of natural dyes and natural mordants vis a vis dyeing

Most of the natural dyes require mordants for their fixation on textile materials. Natural mordants are thus gaining importance in order to get complete-natural dyeing. In the present work, natural dyes and mordants were extracted using conventional and ultrasound methods and comparative studies were made. The natural mordants namely harda and tamarind seed coat and natural dyes like turmeric, henna were extracted using conventional and ultrasound approaches and various extracts obtained were described in terms of their optical densities. In order to verify the extraction efficiencies, wool fabrics were dyed with extracts of various combinations of mordants/dyes and dyed fabrics were evaluated for their colour strengths and fastness properties. The extent of colour extraction was higher in case of ultrasound assisted extraction as compared to that of conventional method. The fabrics dyed using extracts of ultrasound method showed higher colour values as compared to those dyed using extracts from conventional methods thus confirming ultrasound as more efficient method of extraction.     

Adsorption and dyeing characteristics of reactive dyes onto cotton fiber in nonionic Triton X-100 reverse micelles

The nonionic reverse micelles used for dyeing cotton fiber were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The adsorption capacity of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fiber was investigated. The Langmuir and Freundlich isothermals were employed to model the adsorption data. In addition, the color strength and fixation rate of cotton fabrics dyed in the reverse micelles and bulk water were examined and compared. The salt and alkali as influencing factors were also discussed. The FT-IR spectra were employed to study the polarity of water added in reverse micelles. The results indicated that the adsorption of the dyes onto cotton showed better agreement with Langmuir model. The adsorption process was monolayer adsorption. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity. The fixation percentage and color strength of the cotton fiber dyed in TX-100 reverse micelles was higher than those in bulk water. The polarity of water in TX-100 reverse micelles was lower than that in bulk water.     

Effects of low temperature plasma on wool and wool/nylon blend dyed fabrics

Knitted wool and wool/nylon blend dyed fabrics were treated with low temperature plasma (LTP) to achieve optimum shrink-resistance without impairing surface topography, colour or fastness to washing of the fabrics. As LTP tends to impair handle of the fabrics, both wool and wool/nylon blend fabrics were submitted to industrial softening and/or biopolymer treatments after LTP treatment, leading to hydrophilic wool and wool/nylon blend fabrics with improved shrink-resistance without any colour changes and good fastness to washing. The results obtained were compared with those obtained by an industrial shrink-resist treatment.     

Water and dye-free coloration of wool

A water and dye-free heat treatment method was used to color wool fibers. The heat effect changed wool fibers to different colors from white in a nitrogen atmosphere. The influences of heating temperature and time on the colors of wool were investigated and the mechanical property of colored wool fibers was evaluated. The color strength of wool fibers increased as heat treatment temperature and time increased. The tensile strength retention rate of wool fiber was relatively high (≥90 %) when the heat temperature was below 200 °C. The surface morphologies of wool fibers scarcely changed during the heat treatment. The carbon content of fibers was found to reduce by heat treatment, indicating oxidization of components in the wool fibers in the process of coloration. Heat treatment may provide a water and dye-free approach to color wool and other textile fibers, albeit within a limited color range.     

The limiting irregularity of single wool fibers

Fiber irregularity affects fiber mechanical properties. This study has, for the first time, introduced the concept of limiting irregularity to single wool fibers. The limiting irregularity is the minimum variation in fiber cross sectional area that can be expected of a single wool fiber, assuming a random length-wise distribution of its constituent cortical cells. Cortical cells were extracted from merino wool fibers and their dimensions were measured from SEM images to calculate their cross sectional area variations both between cortical cells and within cortical cells, and to work out the average number of cortical cells in the cross section of wool fibers of a given diameter. Single wool fibers were also measured at 5 μm interval along length for fiber diameter variations. These variations were found to be larger than that based on fiber limiting irregularity.     

Characterization of conductive polypyrrole coated wool yarns

Wool yarns were coated with conducting polypyrrole by chemical synthesis methods. Polymerization of pyrrole was carried out in the presence of wool yarn at various concentrations of the monomer and dopant anion. The changes in tensile, moisture absorption, and electrical properties of the yarn upon coating with conductive polypyrrole are presented. Coating the wool yarns with conductive polypyrrole resulted in higher tenacity, higher breaking strain, and lower initial modulus. The changes in tensile properties are attributed to the changes in surface morphology due to the coating and reinforcing effect of conductive polypyrrole. The thickness of the coating increased with the concentration of p-toluene sulfonic acid, which in turn caused a reduction in the moisture regain of the wool yarn. Reducing the synthesis temperature and replacing p-toluenesulfonic acid by anthraquinone sulfonic acid resulted in a large reduction in the resistance of the yarn.     

Dyeing of wool with Marigold and its properties

This research work involves the dyeing of wool with Marigold as a source of yellow colour. To do this, wool yarns pre-treated with Alum as a colorless mordant, dyed with Marigold and then treated with different percentages of ammonia solutions. The chromaticity co-ordinates of samples measured in CIELAB system. TheL* values of all ammonia treated samples decreased and the values ofa*,b*,C* dependent on the ammonia solution. It can also indicate that the reflectance spectrum of treated samples decreases due to ammonia treatment. The rate of vertical wicking decreases on Marigold dyed treated with ammonia. Color hue of the Marigold dyed wool alters after washing with standard soap and ammonia after-treatment has no influence on washing fastness. The samples dyed with Marigold and after-treated with ammonia show a lower light fastness.     

Optimum condition of ink-jet printing for wool fabric

This paper is aimed at studying the optimum content of pre-treatment print paste used for ink-jet printing of wool fabric. Optimum condition of ink-jet printing with respect to the content of pre-treatment print paste and steaming time has been successfully developed through the orthogonal analysis. The parameters of the pre-treatment print paste including sodium alginate, urea and ammonium tartrate, as well as the post-treatment of steaming time right after ink-jet printing have been investigated. The optimum content of the pre-treatment print paste and the proper condition of post-treatment has been developed to achieve higher colour yield for cyan, yellow, magenta and black color (CYMK). The results of the highest colour yield obtained confirm that steaming time is the most dominating factor when compared with the other factors.     

Dyeing behavior of low temperature plasma treated wool

In this paper, the effects of low temperature plasma (LTP) treatment on the dyeing properties of the wool fiber were studied. The wool fibers were treated with oxygen plasma and three types of dye that commonly used for wool dyeing, namely: (i) acid dye, (ii) chrome dye and (iii) reactive dye, were used in the dyeing process. For acid dyeing, the dyeing rate of the LTP-treated wool fiber was greatly increased but the final dyeing exhaustion equilibrium did not show any significant change. For chrome dyeing, the dyeing rate of the LTP-treated wool fiber was also increased but the final dyeing exhaustion equilibrium was only increased to a small extent. In addition, the rate of afterchroming process was similar to the chrome dyeing process. For the reactive dyeing, the dyeing rate of the LTP-treated wool fiber was greatly increased and also the final dyeing exhaustion equilibrium was increased significantly. As a result, it could conclude that the LTP treatment could improve the dyeing behavior of wool fiber in different dyeing systems.     

Impact of Agronomic and Storage Practices on Acrylamide in Processed Potatoes

Acrylamide is a probable carcinogen found in processed potato products. The compound is formed at elevated temperatures by the Maillard reaction from two primary precursors - reducing sugars (fructose and glucose) and asparagine. Significant advances have been made in reducing acrylamide formation by selecting varieties with low precursor concentrations through conventional breeding or genetic modification techniques. However, acrylamide in many of the traditional varieties processed for fries or chips is sometimes found at elevated levels. Both agronomic and storage practices can significantly influence glucose, fructose, and asparagine concentrations and therefore the potential to form acrylamide during processing. This summary of a symposium presentation given at the 99th Annual Potato Association of American Meeting is to provide a general overview of previous studies that have examined the effects of agronomic factors such as nutrient and water management and storage factors such as temperature and duration on acrylamide precursors and/or acrylamide in processed potato products. A better understanding of how these factors affect acrylamide precursors is a first step in minimizing acrylamide formation during processing and improving the quality of processed potato products.     

Functional modification of wool fabric by thiol-epoxy click chemistry

The paper reports modification and characterization of wool fabrics achieved through thiol-epoxy click chemistry. A pretreatment with tris (2-carboxyethyl) phosphine (TCEP) as an effective reducing agent was carried out to produce thiol groups on wool surface. Glycidyl trimethyl ammonium chloride (GTAC) was later covalently bonded with wool fibers via thiol-epoxy reaction. The reaction was confirmed by SEM, FTIR, Raman and TG analysis. Antibacterial activity, antistatic property, hydrophilicity and dyeability of treated wool fabric were assessed. The results demonstrated that TCEP-GTAC treatment can endow wool fabric good antibacterial and antistatic properties as well as improved hydrophilicity. Tensile strength studies indicated fiber strength loss of ~12 % on modification.     

Effect of wool surface modification on fluorocarbon chain re-orientation

There is an increasing demand for air-dry performance of fluorocarbon finished materials. Thus, surface modifications of wool fabrics were evaluated. Untreated, gaseous fluorinated, Chlorine/Hercosett processed 100 % wool fabrics were treated with different fluorochemicals and their liquid repellency after washing, and dry cleaning were evaluated. The results indicated that Chlorine-Hercosett treated samples, wool with a positive charge, after few washing cycles, showed better air dry performance with higher level of repellent properties. In addition, the comparison of the wool surface modifications treatment with different applied fluorochemicals, with different commercial formulations, illustrated that the fluorocarbon chain re-orientation and fastness properties are more affected by the nature of the wool surface while the used fluorocarbons showed more or less similar behaviours. In general, the fluorination increases fabric stiffness with lower fabric formability. The surface interface was effectively probed by X-ray Photoelectron Spectroscopy, XPS, which enabled the characterisation of the loss of surface lipids, the nature of the fibre oxidation and the deposition of fluoropolymers.     

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.     

The effect of a new setting agent for wool

Pleated wool fabrics were prepared by the treatment with ethylenediamine (EDA) at 90°C for 30 min. The degree of set, tensile property and dyeing of the treated fabrics have been discussed in relation to the concentration of EDA in the treatment system. No significant decreases in tensile strength and elongation, and great increases of exhaustion of synthetic and natural dyes were observed. Pleat and flat set were successfully attained in a wide range of the concentration of EDA. Excellent dyeability and setability of the fabrics obtained were considered to be associated with the existence of new crosslink, β-N-(2-aminoethyl)alanino-β-aminoalanine and the pendant group, β-N-(2-aminoethyl) aminoalanine produced by the reaction of EDA with dehydroalanine intermediate.     

High yield preparation of keratin powder from wool fiber

A descaling and oxidation pretreatment was employed to maximize the yield of cortical cells in the disintegration process of wool fiber. The results indicated that the productivity of intact cortical cells was greatly increased by moderate oxidation pretreatment in 1.6 % per-acetic acid within 2 h, but the yield would be decreased by further oxidation pretreatment. In order to give a reasonable explanation for this fact, the effect of the increasing time of oxidation pretreatment on the yield of intact cortical cells was investigated by means of spectral analysis using FT-IR and XRD. The intensity of the peak at 1040 and 1173 cm^?1 in FT-Infrared spectrum gradually increased with increasing oxidation pretreatment time, suggesting that more and more SS bonds were cleaved to form cysteic acid. X-ray Diffraction investigation showed that the crystallinity of wool fiber obviously decreased when the time of oxidation pretreatment exceeded 2 h. The combined results of FT-IR and XRD revealed that SS bonds in the amorphous region of wool fiber were first cleaved in the fiber components. The selective cleavage of SS bonds in the amorphous region by the appropriate oxidation pretreatment can effectively decrease the bonding force between the components of wool fiber and enhance the yield of intact cortical cells.