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.     

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.     

The effects of humidity on the surface modification of wool fabric through atmospheric pressure plasma jet

Current research was carried out on hydrophilic wool fibers at three different humidity conditions through atmospheric pressure plasma jet (APPJ). Samples were taken to evaluate surface microscopic morphology, surface roughness, directional friction effect (DFE), and surface chemical composition. The scanning electron microscope (SEM) and fiber friction coefficient test (FFT) results show that wetting pretreatment has significant effect on surface etching and DFE, but very limited effect on surface roughness. Allwörden reaction and X-ray photoelectron spectroscopy (XPS) results reveal that extra moisture changes C, O, N, S contents and their related characteristic functional groups, therefore increases etching degree on wool fiber surface scales. It was concluded that APPJ treatment is effective in processing wool fiber with high moisture contents.     

A comparative study of wool fibre surface modified by physical and chemical methods

The wool scale present on the fibre surface gives rise to certain unwanted effects such as felting and poor wettability in textile wet processing. In general practice, the removal of scale was done either by surface modification through physical/chemical degradation of scale or by deposition of a polymer on the scale. In modern treatment, combination of both methods is usually carried out. Since the deposition of a polymer on the fibre surface depends much on the surface characteristic of the fibre, therefore, the surface property of modified fibre is an important factor for polymer application. On the other hand, the surface modification methods may also result in improved hydrophilicity of fibre. The present paper investigated the surface physico-chemical properties of wool fibre under the influence of different surface modification treatments: (i) low temperature plasma (LTP) treatment with nitrogen gas and (ii) chlorination. The surface physico-chemical properties of the LTP-treated and chlorinated wool fibres were studied which included contact angle measurement with different solvents, determination of critical surface tension and surface free energy. Experimental results showed that these selected properties were altered after the surface modification treatments. In addition, a polymer was deposited in the treated wool fabrics and scanning electron microscope was used for assessing the surface morphology.     

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.     

A study of the oxygen plasma treatment on the serviceability of a wool fabric

Low temperature plasma (LTP) treatment using oxygen gas was applied to a wool fabric. The LTP treated wool fabric was tested with several methods: ASTM D5035-1995, ASTM D1424-1996, AATCC Test Method 99-2000, AATCC Test Method 61-2001 1A, AATCC Test Method 15-2002 and AATCC Test Method 8-2001 and the results were compared with the industrial requirements (ASTM D3780-02 and ASTM D4155-01). The results revealed that the LTP treated wool fabric could fulfil the industrial requirements. The results of the investigation were discussed thoroughly in this paper.     

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.     

Diameter variations of irregular fibers under different tensions

The cross-section area of animal fibers varies along the fiber length, and this geometrical irregularity has a major impact on the mechanical properties of those fibers. In practice fibers are often subjected to tensile stresses during processing and application, which may change fiber cross-section area. It is thus necessary to examine geometrical irregularity of fibers under tension. In this study, scoured animal fibers were subjected to different tensile loading using a Single Fiber Analyzer (SIFAN) instrument. The 3D images of the fiber specimens were first constructed, and then along-fiber diameter irregularities of the specimens were analyzed for different levels of tensile loading. The changes in effective fineness of the fiber specimens were also discussed. The results indicate that for the wool fibers examined, there is considerable discrepancy in the fiber diameter results obtained from the commonly used single scan along fiber length and that from multiple scans at different rotational angles, and that the diameter variation along fiber length increases as fiber tension increases. The results also show that when diameter reduction treatments are applied to wool by stretching, the reduced average fiber diameter is associated with an increase in both within-fiber and between-fiber diameter variations. So in terms of effective fineness, the change is much smaller than the difference between the average diameters of the parent and treated wool. These results have significant implications for improving the accuracy of fiber diameter measurement and evaluation.     

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.     

Identification of wool, cashmere, yak, and angora rabbit fibers and quantitative determination of wool and cashmere in blend: a near infrared spectroscopy study

Near infrared spectroscopy coupled with chemiometric analysis was investigated as a fast and non destructive method for the identification of wool, cashmere, yak, and angora rabbit fibers in the raw and combed sliver state and for the quantitative determination of cashmere in cashmere/wool blends. The main differences among spectra of different animal hair arise from physical charateristics rather than chemical characteristics (mainly pigmentation and mean diameter) of animal fibers. The Soft Independent Modelling by Class Analogy method allows the classification of distinct fibers into separate groups with interclass distances ranging from 12.64 for the nearest classes (white cashmere and wool) to above 1000 for the most distant classes of white and pigmented fibers. Percentages of recognition and rejection of 100 % were found with the exception of a yak sample that was not rejected from the pigmented cashmere class (98 % of rejection). The prediction capacity of the model was also evaluated. Quantitative analysis was carried out using samples obtained by carefully mixing known amounts of wool and white cashmere. A standard error of the estimate of 8.5, a standard error of prediction of 13.10 and a coefficient of determination of 0.95 were calculated. From the results obtained, it can be concluded that near infrared spectroscopy can be used as a tool for an initial and rapid screening of unknown animal fiber samples in the raw and combed sliver states and for a fast and coarse estimate of the amount of cashmere in wool/cashmere blends.     

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.     

Atmospheric plasma advantages for mohair fibers in textile applications

In this study, mohair fibers were treated by air and argon plasma for modifying some properties of fibers. The fibers were evaluated in terms of their hydrophilicity, grease content, fiber to fiber friction, shrinkage, dyeing, and color fastness properties. The surface morphology was characterized by SEM images. The results showed that the atmospheric plasma has an etching effect and increases the functionality of a wool surface, which is evident from SEM and FTIR-ATR analysis. The hydrophilicity, dyeability, fiber friction coefficient, and shrinkage properties of mohair fibers were improved by atmospheric plasma treatment.     

Mechanical properties of wool fiber in the stretch breaking process

Short wool fibers obtained by the stretch breaking process can be blended with cotton fibers and processed in a cotton spinning system, which has a high production rate. For the structural property of the wool fiber after stretch breaking, the diameter and length of the wool fiber were measured as a function of time. The diameter of the broken fibers was finer than the diameter of untreated fibers. The fiber diameter at the break point was the finest and was more irregular than the original fiber. The broken fiber showed mechanical properties of increased modulus, decreased breaking strain, and increased breaking strength.     

Frost kill and kenaf fiber quality

Kenaf (Hibiscus cannabinus) grown in northern Mississippi and elsewhere often is injured by early frost and killed before harvest. Frost kill often is associated with fungal growth or rot, so its effect on fiber quality is a major concern. Fiber processing also affects the quality and chemical composition of fibers. Therefore, this study was aimed at determining the effects of frost kill on processing, fiber quality and chemical composition of kenaf fibers. Frost-damaged kenaf with fungal growth was decorticated by hand and divided into six sections (26.88 cm/each) from the base to tip of the stem and then retted chemically or bacterially in the laboratory. Fiber characteristics were compared between the two processes and the six locations on the plant. Ash, cellulose, hemicellulose, and lignin contents of the resultant fibers were measured. Bacterially retted (BR) fibers were stronger (11.8 g/tex) than the chemically retted fibers (CR), 7.5 g/tex, at all locations. The BR fibers from decorticated green ribbons were stronger than those from frost-killed ribbons. However, no significant differences occurred between the CR fibers from decorticated and frost-killed ribbons. Residual gum content was higher for the BR fibers (23.3%) than for the CR fibers (8.1%). The stretch properties were not affected significantly by the frost kill or fungus. The base of the stem had the weakest fibers in both processes, which may have been due to greater fungal disease. The CR process extracted more fiber than the BR process, with a consistent higher yield of clean fibers. In the BR process, the fiber extracted was higher at the tip than at the base of the stem. This may have been related to the presence of fungus, which inhibits the BR process. Analysis of chemical composition of the processed fibers indicated that CR is efficient in reducing hemicellulose and lignin contents. These results indicate that frost kill may not be the appropriate method for harvesting kenaf for quality fibers. However, fibers extracted by chemical retting were unaffected by the presence of fungus as a result of frost kill.     

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.     

Surface modification of HMPBO fibers by silane coupling agent of KH-560 treatment assisted by ultrasonic vibration

The surface modification of poly (p-phenylene-2,6-benzobisoxazole) (HMPBO) fibers by silane coupling agent of ??-aminopropyl triethoxy silane (KH-560) treatment assisted by ultrasonic vibration was investigated. The chemical composition and surface morphologies of the HMPBO fibers were analyzed and characterized by XPS, FTIR, TGA and SEM. The tensile properties of the HMPBO fibers were also studied. The results indicated that polar hydroxyl groups were successfully introduced on the HMPBO surface after the proposed treatment processes, and the surface roughness of HMPBO fibers was increased. Moreover, the treated HMPBO maintained relatively excellent tensile strength, and the single fiber pull-out strength of HMPBO was improved from 0.94 MPa to 1.07 MPa.     

Relationship between chemical composition,crystallinity, orientation and tensile strength of kenaf fiber

The physical properties of natural growth fibers such as chemical composition content and fiber diameter are highly affected by environmental issues such as environmental changes and fiber extraction methods. These irregularities of the natural fibers seriously affect its utilization in composite as reinforcements. In this study, taking into account the importance of the fiber tensile strength, the correlation degrees between the kenaf fiber tensile strength and the fiber chemical composition, crystallinity, orientation degree were analyzed by the grey relational analysis method. Both the kenaf single fiber and fiber bundle were used as XRD and tensile strength test sample. The chemical composition content and the FTIR were carried out to obtain a correct result of the chemical composition content. It found that for the different XRD and tensile strength test samples, the single fiber showed lower crystallinity, higher orientation degree and tensile strength compared with the fiber bundle. The cellulose content and the orientation degree got the higher correlation degree with single fiber tensile strength, which was 0.674 and 0.640. The highest factor associated with the fiber bundle tensile strength was the orientation degree, the correlation degree was 0.747. The hemicellulose content and the crystallinity also got high correlation degree with the fiber bundle strength, which was 0.687 and 0.640.     

Preparation and characterizations of polypyrrole on liquid ammonia pre-treated wool fabric

Wool fabric was treated with liquid ammonia at -40 °C for 30 and 60 s prior to the application of polypyrrole (PPy). The polymer was deposited on wool fiber using the chemical oxidation method with 0.02 and 0.05 mol/l (Py) monomer concentration and FeCl₃ as a catalyst. Functional groups of wool samples were analyzed using FT-IR, and surface morphology was investigated using SEM micrographs. Properties such as water absorbency, surface resistivity, abrasion resistance, weight add-on, and air permeability of coated specimens were explored. The FT-IR outcomes revealed the liquid ammonia pre-treatment changed the amount of amide I (NH), cystic acid, cystic monoxide, and dioxide content of the fiber. SEM micrographs revealed the descaling of wool surface after pre-treatment and smooth coating of polymer. Pre-treatment of wool in liquid ammonia improved absorbency of wool fabric with respect to the treatment duration. The surface resistivity of wool fabric decreased with the increase of monomer concentration and pre-treatment duration. The results of abrasion resistance confirmed that the pre-treated fabric exhibited lower loss of polymer after 200 cycles of abrasion. The weight of the fabric was increased and air permeability decreased when the monomer concentration and liquid ammonia pre-treatment duration was increased.     

The effects of wool surface characteristic on fuzzing and pilling of knitted fabrics

The fuzzing and pilling of untreated, chlorinated and oxidized wool knitted fabrics were compared with frictional coefficients measured by capstan method, surface modification observed by scanning electron microscopy (SEM), the surface roughness and the scale height assessed by atomic force microscopy (AFM), and hairiness imaged on the three-dimensional rotational microscopy. The pilling comparative experiments of the corresponding knitted fabrics were conducted by means of Pillbox method. Experimental results showed that some scales on the oxidized fiber surface were partially cleaved and some grooves generated. With oxidization treatment, the anti- and with-scale of friction coefficient increase with decreasing the thickness of scales and the yarn hairiness. There is good correlation between the result of AFM and the change in frictional coefficients. The pilling grade of knitted fabric comprised of oxidization wool is 2.5, and the average numbers of pills per 25 cm² is 25. It is postulated that the surface topography, the frictional properties of oxidized wool fibers and surface hairs of corresponding yarns may limit the ability of those surface fibers to form fuzz and of those fuzz for pill formation.     

汉(大)麻与其它纤维素纤维染色性能研究

本文在汉麻纤维化学组分分析的基础上,利用中温活性染料,对多种纤维素纤维的染色性能进行了测定。研究了不同组成成分对汉麻纤维染色性能的影响,比较了汉麻纤维与其它纤维素纤维的上染百分率和上染速率的差异。结果表明,果胶和木质素的含量对汉麻纤维的染色性能均有不同程度的影响,但果胶的影响较木质素更为明显,汉麻纤维的染色性能与苎麻接近,但比棉纤维要差,更低于再生纤维素纤维。