Abstract:The lyocell fiber is become very popular in the recent time among the researcher due to its higher strength, rigid crystalline morphology and its proximity towards to cotton. Lyocell fiber gives higher mechanical modulus which substantially makes it an effective material for use in different biometerials, paper industry, nonwoven fabric or even in packaging purpose. The spinning of this kind of fiber is very challenging due to its several composite steps like-NMMO preparation (raw material), preparation of a p… Show more
“…Cellulose is an important textile substrate due to its biodegradable, biocompatible, eco-friendly, non-toxic, and renewable properties [4]. It is chosen according to its high mechanical modulus property, a high strength and an inflexible crystallinity [5]. Several approaches are reported in the literature about how conductive substrates are implemented in large area fabrics.…”
Integration of sensors in textile garments requires the development of flexible conductive structures. In this work, cellulose-based woven lyocell fabrics were coated with copper during an electroless step, produced at 0.0284 M copper sulfate pentahydrate, 0.079 M potassium hydrogen L-tartrate, and 0.94 M formaldehyde concentrations. High concentrations led to high homogeneous copper reaction rates and the heterogeneous copper deposition process was diffusion controlled. Thus, the rate of copper deposition did not increase on the cellulose surface. Conductivity of copper coatings was investigated by the resistance with a four probe technique during fabric deformation. In cyclic tensile tests, the resistance of coated fabric (19 × 1.5 cm2) decreased from 13.2–3.7 Ω at 2.2% elongation. In flex tests, the resistance increased from 5.2–6.6 Ω after 5000 bending cycles. After repeated wetting and drying cycles, the resistance increased by 2.6 × 105. The resistance raised from 11–23 Ω/square with increasing relative humidity from 20–80%, which is likely due to hygroscopic expansion of fibers. This work improves the understanding of conductive copper coating on textiles and shows their applicability in flexible strain sensors.
“…Cellulose is an important textile substrate due to its biodegradable, biocompatible, eco-friendly, non-toxic, and renewable properties [4]. It is chosen according to its high mechanical modulus property, a high strength and an inflexible crystallinity [5]. Several approaches are reported in the literature about how conductive substrates are implemented in large area fabrics.…”
Integration of sensors in textile garments requires the development of flexible conductive structures. In this work, cellulose-based woven lyocell fabrics were coated with copper during an electroless step, produced at 0.0284 M copper sulfate pentahydrate, 0.079 M potassium hydrogen L-tartrate, and 0.94 M formaldehyde concentrations. High concentrations led to high homogeneous copper reaction rates and the heterogeneous copper deposition process was diffusion controlled. Thus, the rate of copper deposition did not increase on the cellulose surface. Conductivity of copper coatings was investigated by the resistance with a four probe technique during fabric deformation. In cyclic tensile tests, the resistance of coated fabric (19 × 1.5 cm2) decreased from 13.2–3.7 Ω at 2.2% elongation. In flex tests, the resistance increased from 5.2–6.6 Ω after 5000 bending cycles. After repeated wetting and drying cycles, the resistance increased by 2.6 × 105. The resistance raised from 11–23 Ω/square with increasing relative humidity from 20–80%, which is likely due to hygroscopic expansion of fibers. This work improves the understanding of conductive copper coating on textiles and shows their applicability in flexible strain sensors.
“…The forces include the hydrogen bonds within the chain (intramolecular) and between the neighboring chains (intermolecular), as well as the van der Waals forces and hydrophobic forces. The dissolution occurs when such a solvent is introduced to polymer which is able to disturb the mutual interaction of the polymer molecules [2].…”
In this study, NaOH dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type Al-Zahdi) taken from Iraqi gardens. In this process, (NaOH)-solution is brought into contact with the cellulose fibers at low temperature. Experiments were conducted with different concentrations of NaOH (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oC) and (-20oC). Maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of NaOH and at cooling bath temperature of -20oC. In order to enhance the cellulose fibers dissolution, the sample was pretreated with Fenton's reagent which consists of hydrogen peroxide (H2O2), oxalic acid (C2H2O4) and ferrous sulfate (FeSO4). This reagent reacts with cellulose fibers and produces free radicals which increase cellulose dissolution. In this work three variables were studied: cooling bath temperature (-15oCand-20oC), NaOH concentration (4%, 6%, 8% and12%) and time of Fenton's reagent treatment (1-48) hrs. The results showed that the best percent of cellulose dissolution was (42 wt %) which occurred at treatment time (24 hours), temperature (-20oC) and NaOH concentration 8%. In another set of experiments urea was added to NaOH solution as a catalyst with proportion (6%NaOH+4% urea) at two temperatures -15 and -20 oC. The results show that the solubility of cellulose increase to 62% for the sample which treated with Fenton's reagent and to 35% for the untreated sample, both values were obtained at -15oC.
“…The structural property of Tencel fiber aids the human body to achieve an optimum temperature by regulating the absorption and transfer of moisture. 18,20,29,58 Figure 8 shows that the water vapor permeability values of the fabric samples increased as Tencel percentages of the blends increased, and a blend with 50% Tencel was sufficient to achieve the optimum water vapor permeability. Figure 7.SEM images of finished fabrics from process 2: (13 and 14) 100% cotton, (15 and 16) 100% Tencel, (17 and 18) 50/50 Tencel/cotton.…”
Section: Resultsmentioning
confidence: 99%
“…4,17 If Tencel fabrics are subjected to mechanical processes in a dry state, or if mechanical processes are not applied to them in a wet state, the fibers do not fibrillate. 18 Fibrillation of the fabric surface leads to the formation of ''pills'' ranging from one to four microns in length. 4,17 In order to prevent formation of pills on fabric surfaces during normal wear and use, Tencel fabrics need to be subjected to finishing processes which include primary fibrillation, defibrillation and secondary fibrillation.…”
This study aimed to investigate the comfort and physical properties of raw and finished knitted fabrics made of yarns with different Tencel/cotton blend ratios. For this purpose, Ne 20 yarns were produced with the same twist coefficient on the same production line. Fabric samples were produced on the same knitting machine. The raw fabrics were subjected to two different combined enzymatic pre-treatments and dyeing processes. In the first process, enzymatic defibrillation and dyeing were carried out in the same bath. In the second, enzymatic bleach clean-up, defibrillation and dyeing were conducted in the same bath. The comfort and physical properties of all the raw and finished fabric samples were measured according to the relevant standards. The results were assessed statistically. The results of this study showed that with increased percentage of Tencel in the blend, the water vapor and air permeability, fabric roughness, pilling, thermal absorption and loss of mass values of the fabrics increased, whereas thermal conductivity values decreased. It was observed that the fabrics which were subjected to enzymatic defibrillation and dyeing processes in a single bath gave lower surface roughness and abrasion values but higher air permeability values; while those subjected to enzymatic bleach clean-up, defibrillation and dyeing in a single bath gave higher thermal conductivity and thermal absorptivity values. Comparison of the two processes showed that there were no significant differences in the pilling and the water vapor permeability values obtained from both processes.
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