Platinum recovery using inherently conducting polymers and common fabrics

The recovery of platinum from solutions containing [PtCl₆]²⁻ using inherently conducting polymer (ICP) powders, membranes and coated fabrics has been investigated. Polyaniline (PAn) powders were able to recover platinum from solution, whereas polypyrrole (PPy) powders and membranes displayed almost no ability to perform this task. Uncoated pieces of nylon and nylon-lycra showed a significant capacity to recover platinum metal, unlike each of the other common fabrics investigated. Surprisingly the amount of platinum recovered by nylon-lycra was not improved by coating the fabric with a layer of ICP. Pieces of nylon-lycra that had previously been soaked in solutions containing [PtCl₆]²⁻ released only a small percentage of the bound metal when treated with 5 % HCl. However, subsequent treatment with aqua regia released all of the remaining platinum. A mechanism of platinum recovery by nylon and nylon-lycra involving coordination to functional groups present in their polymeric structures is proposed.     

Lipase treatment of polyester fabrics

The aim of this paper is to improve moisture regain of PET fabrics using a lipase treatment. Effects of nine lipase sources, lipase activator and nonionic surfactant on moisture regain of PET fabrics are examined. Moisture regains of lipase-treated samples improve by two times in average compared with untreated and buffer-treated samples. Alkaline treatment creates larger pitting by more aggressive attack into fiber which is proved by SEM and water contact angle measurement. Moisture regain by alkaline treatment (0.568 % ± 0.08) does not improve. However, lipase-treatment (L2 treatment) improves moisture regain up to 2.4 times (1.272 % ± 0.05). Although lipase treatment is more moderate than alkaline treatment, lipase hydrolysis on PET fabrics improves moisture regain, efficiently. K/S values improved confirm that carboxyl and hydroxyl groups are produced on the surface of PET fabrics by lipase hydrolysis. Moisture regain and dyeability improve by lipase hydrolysis on PET fabrics.     

Fabrication of electromagnetic shielding polyester fabrics with carboxymethyl chitosan-palladium complexes activation

Electromagnetic shielding polyester fabrics were prepared using carboxymethyl chitosan-palladium (CMCS-Pd) complexes as activation solution, followed by electroless nickel plating. CMCS-Pd complexes were prepared by the complexing adsorption between CMCS and Pd²⁺. The effects of reaction time and pH value on the adsorption of Pd²⁺ by CMCS were discussed. The maximum adsorption capacity was calculated as 4.27 mmol/g. CMCS-Pd complexes were characterized by ultraviolet (UV) spectrophotometer and Fourier transform-infrared (FTIR) spectroscopy. The induction time of electroless plating decreased gradually with the increase of Pd²⁺ concentration. The lowest surface resistance 125 mΩ/sq of the treated polyester fabric was obtained when Pd²⁺ concentration in CMCS-Pd complex was 1.5 g/l. The prepared polyester fabrics had excellent electromagnetic shielding effectiveness (SE) of 40–60 dB. The treated polyester fabrics were also characterized by scanning electron microscopy (SEM). Results showed that CMCS-Pd was effective to form an active catalyzed layer on polyester substrate and the 1.5 g/l Pd²⁺ was sufficient to initiate electroless nickel plating reaction. The CMCS-Pd complex activation and electroless nickel plating treatment caused small changes in the polyester fabrics’ tensile strength and air permeability.     

Surface modification of polyester fabrics by enzyme treatment

In this study, the effect of enzymatic hydrolysis using lipase and cutinase on poly(ethyleneterephthalate) (PET) fabrics was investigated in an attempt to improve the hydrophilicity of these fabrics. The hydrolytic activity of the enzymes was expressed for variations in pH levels, temperatures, enzyme concentrations, and treatment times. The effects of using a nonionic surfactant were examined by measuring moisture regain and surface wettability. Finally, the fabric characteristics that were affected by enzyme treatment were evaluated by tensile strength and scanning electron microscopy. The optimal treatment conditions for lipase were determined to be a pH of 4.2, a temperature of 50 °C, a lipase concentration of 100 %, and a treatment time of 90 min; those for cutinase were determined to be a pH of 9.0, a temperature of 50 °C, a cutinase concentration of 100 %, and a treatment time of 60 min. At optimal enzymatic treatment conditions, we got the significant results of increase on the moisture regain and the water contact angle (WCA) and water absorbency effectively decreased. Triton X-100 facilitated cutinase hydrolysis on PET fabrics; however, it was ineffective for lipase. With enzymatic treatment, the tensile strength did not decrease.     

Effect of hollow polyester fibres on mechanical properties of knitted wool/polyester fabrics

The physical and mechanical characteristics of hollow polyester fibres were compared with solid polyester fibres in order to establish their processing behaviour and performance characteristics. The effects of hollow fibres on fabric properties were investigated by using microscopy and tests of tensile and bursting strength, pilling, abrasion resistance, water vapour permeability, and handle. The results show that tensile strength of hollow polyester fibres and yarns are negatively affected by the cavity inside the fibre. Hollow fibres also have higher stiffness and resistance to bending at relaxed state. Fabrics made from hollow polyester/wool blends and pure wool fabrics show three distinguishable steps in pilling. During pilling, hollow fibres break before being pulled fully out of the structure, leading to shorter protruding fibres. Microscopy studies showed that the breakdown of hollow fibres started during entanglement by splitting along the helical lines between fibrils. KES results showed that the friction between fibres and the fibre shape are the most important parameters that determine the fabric low stress mechanical properties. However, in some aspects, the hollow structure of the fibre does not have a significant effect.     

Reflectance prediction of colored polyester fabrics by a novel formula

This paper focuses on the reflectance prediction of colored (unicolored) fabrics considering relationship between fractional reflectance values and cover factors of fabrics woven from polyester yarns. A novel equation for the calculation of relation between fractional reflectance and cover factor was proposed and usage of the equation was assessed by reflectance measurements. 48 dyed polyester fabrics having different constructional parameters were used and fabrics differed from each other by their cover factors. Warp yarn type and count, warp density and warp yarn twist were the same but weft yarn count, weft yarn fiber count and weft density were different for the fabrics in experimental sub-groups. The reflectance measurements were conducted on the dyed fabric samples as well as on the individual yarn systems (warp and weft) of the same fabrics. The proposed equation was tested according to different fabric constructional parameters and reasonable results with the experimental data were obtained. The possibilities of general use of derived mathematical relations between theoretical and measured reflectance values were researched. The relation obtained was used to explain the effects of different constructional parameters on reflectance behavior of fabric surfaces.     

Evaluation of comfort properties of polyester knitted spacer fabrics finished with water repellent and antimicrobial agents

In order to impart barrier properties against water and microorganisms on breathable three dimensional spacer fabrics as medical or technical textiles, fabric samples were treated with two water repellent agents and a quaternary ammonium salt namely cetyltrimethylammonium bromide (CTAB), using pad-dry-cure method. Two different water repellent agents based on hydrocarbon and acrylic copolymer were used. The water repellent property of samples was tested by Bundesmann and contact angle tests. Antimicrobial activity of samples was analyzed quantitatively according to AATCC 100. Simultaneous finishing of samples was done with 3 % CTAB and 4 % fluoroalkyl acrylic copolymer. To study the effect of various treatments on comfort related properties, air and water vapor permeability, water repellency and compression were measured. The results showed that the antimicrobial and water repellent spacer fabrics can be achieved applying selected material without significant changes on their comfort properties. Also a regression model was presented to predict the water vapour permeability of knitted spacer fabrics based on course density (CPC) changing.     

Optimization of papain treatment for improving the hydrophilicity of polyester fabrics

The goal of this study was to establish optimal conditions for improving the hydrophilicity of polyester fabrics. The hydrolytic activity of papain was determined by measuring the number of carboxylic groups in the treatment solution. Papain treatment conditions-such as pH, temperature, treatment time, and enzyme concentration-were optimized by measuring hydrolytic activity, moisture regain, and wettability. Optimal papain treatment conditions were identified as a pH of 7.5, temperature of 30 °C, treatment time of 60 min, and papain concentration of 100 %(o.w.f.). The moisture regain for polyester fabrics treated with papain improved to 1.28±0.02 %, a 2.7-fold increase compared to that of untreated polyester fabrics. As the hydrolytic activity increased, the moisture regain and wettability of the treated fabrics improved. L-cysteine and sodium sulfite did not affect the moisture regain of papain-treated polyester fabrics.     

Predicting the air permeability of polyester/cotton blended woven fabrics

The aim of this study was to model the air permeability of polyester cotton blended woven fabrics. Fabrics of varying construction parameters i.e. yarn linear densities and thread densities were selected and tested for air permeability, fabric areal density and fabric thickness. A total of 135 different fabric constructions were tested among which 117 were allocated for development of prediction model while the remaining were utilized for its validation. Four variables were selected as input parameters on basis of statistical analysis i.e. warp yarn linear density, weft yarn linear density, ends per 25 mm and picks per 25 mm. Response surface regression was applied on the collected data set in order to develop the prediction model of the selected variables. The model showed satisfactory predictability when applied on unseen data and yielded an absolute average error of 5.1 %. The developed model can be effectively used for prediction of air permeability of the woven fabrics.     

Optimization of polymerization conditions and thermal degradation of conducting polypyrrole coated polyester fabrics

PET fabric is coated with conducting polypyrrole (PPy) by oxidative polymerization from an aqueous solution of Py using ferric chloride hexahydrate (FeCl₃) as oxidant and p-toluene sulphonate (pTSA) as dopant. The optimum concentrations for Py, FeCl₃ and pTSA were found to be 0.11, 0.857 and 0.077 mol/l respectively, which yielded a conductive fabrics with resistivity as low as 72 Ω/sq. PPy fabric gained resistivity less than one order of magnitude when aged for 18 months at room temperature. The stabilizing effect of the dopant pTSA against thermal degradation was demonstrated; the undoped samples reached resistivity of around 40 kΩ, whereas doped samples reached less than 2 kΩ at the same temperature and time.     

Electrically conductive and hydrophobic cotton fabrics by polypyrrole-oleic acid coating

Hydrophobic polypyrrole-coated fabrics with improved electrical conductivity were produced embedding oleic acid as counter-ion. Hydrophobisation of polypyrrole was carried out by means of an ion exchange process after deposition of polypyrrole on cotton fabrics. The fabrics coated with oleic acid-doped polypyrrole showed contact angle of 111°, drop absorption time of 7 minutes and high water repellence, while electrical conductivity increased of ～2 times and heat generation improved, too. Moreover, oleic acid demonstrated a great stability as counter-ion in polypyrrole matrix being present also after washing.     

Synthesis of self-crosslinking fluorinated polyacrylate soap-free latex and its waterproofing application on cotton fabrics

Fluorinated polyacrylate latexes are preferably candidates for the textile water repellent finishes as a result of their special surface property and especially economical, low-toxic characteristics compared to fluorinated polyacrylate solutions. The benefits of soap-free latex prepared from reactive surfactants are now well known. We herein used a reactive emulsifier, ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86), to prepare novel self-crosslinking fluorinecontaining polyacrylate soap-free latex (FMBN) with core-shell structure by co-polymerization of dodecafluoroheptyl methacrylate (DFMA), methyl methacrylate (MMA), butyl acrylate (BA), and N-methylolamide (NMA), and then treated the cotton fabric with FMBN. Results showed that the as-prepared latex particles had the uniform spherical core-shell structure with an average diameter of 116 nm. FMBN could form a smooth resin film on the treated fabric/fiber surface under Field emission scanning electron microscopy (FESEM) observation, but some protuberances appeared on that surface from Atomic force microscopy (AFM) image. X-ray photoelectron spectroscopy (XPS) analysis indicated the fluoroalkyl groups tended to enrich at the film-air interface. Hydrophobicity of the FMBN treated fabric was superior to that of the fabrics treated by general emulsion and the non-crosslinking one. In addition, the above three latexes didn’t influence whiteness of the treated fabrics at all. However, they all, and in especial two self-crosslinking latexes would make the treated fabrics stiffer compared to non-crosslinking one.     

Predicting the tensile strength of polyester/cotton blended woven fabrics using feed forward back propagation artificial neural networks

Tensile strength plays a vital role in determining the mechanical behavior of woven fabrics. In this study, two artificial neural networks have been designed to predict the warp and weft wise tensile strength of polyester cotton blended fabrics. Various process and material related parameters have been considered for selection of vital few input parameters that significantly affect fabric tensile strength. A total of 270 fabric samples are woven with varying constructions. Application of nonlinear modeling technique and appreciable volume of data sets for training, testing and validating both prediction models resulted in best fitting of data and minimization of prediction error. Sensitivity analysis has been carried out for both models to determine the contribution percentage of input parameters and evaluating the most impacting variable on fabric strength.     

The effect of fabric balance and fabric cover on surface roughness of polyester fabrics

The effects of fabric balance and fabric cover on surface roughness values of textured polyester woven fabrics with different constructional parameters were investigated. The warp yarn properties (type, count and warp density) were kept constant while the effect of variation in weft yarn density and weave pattern were studied. Measurements were conducted on pre-treated white fabric samples and the results assessed in relation to their constructional properties. A general overview of the results showed that surface roughness values of polyester fabrics affected by fabric balance and fabric cover and the effects were related to fabric thickness, yarn densities, yarn crimp, positioning of yarns in fabric structure. A change in weave pattern from sateen to plain increased the fabric balance and fabric cover, but decreased the surface roughness. Similarly, an increase in weft density increased the fabric balance and fabric cover, but decreased surface roughness. In order to produce fabrics with smooth surface properties yarn density should be increased, yarn float lengths decreased, cover of fabrics increased and fabric balance improved.     

The study of coloration and antibacterial efficiency of corona activated dyed polyamide and polyester fabrics loaded with Ag nanoparticles

The aim of this study was to examine the influence of dyeing on antibacterial efficiency of corona activated polyamide and polyester fabrics loaded with colloidal Ag nanoparticles as well as the influence of the presence of Ag nanoparticles on the color change of dyed fabrics. C.I. Acid Green 25 and C.I. Disperse Blue 3 were used for dyeing of polyamide fabrics and C.I. disperse violet 8 for polyester fabrics. The color change of polyamide fabrics depends on the dye type, which was generally lower compared to polyester fabrics. Antibacterial efficiency of Ag loaded fabrics was tested against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli. Corona activated polyester and polyamide fabrics showed excellent antibacterial efficiency independently of order of dyeing and Ag loading. The morphology of fibers loaded with Ag nanoparticles was assessed by SEM and atomic absorption spectroscopy for elemental analysis.     

Application of PU-sealing into Cu/Ni electroless plated polyester fabrics for e-textiles

Electroless metal plated fabrics are favorable to be used as e-textiles due to the excellent conductivity and peculiar properties of textiles such as flexibility. But, the electrical durability is not enough to be used as e-textiles. Therefore, we applied polyurethane(PU)-sealing (single-sealing vs. double-sealing) onto the electroless metal plated polyester fabrics (Ripstop vs. Mesh) to reinforce the electrical durability. We investigated the changes of electrical properties of the PU-sealed metal plated fabrics after laundering by a multi-meter, examined the surface changes using scanning electron microscope, and checked the metal existence using energy dispersive X-ray spectroscopy. And, we finally proved the possibility of the fabric strips as transmission lines by alternating conventional earphone lines. PU double-sealing showed higher performance on Ripstop polyester fabrics even after being laundered 10 times, which was almost the same as Cu-based typical conductive lines did.     

Analysis and tensile characterization of air-entangled textured polyester woven fabrics depending on interlacement and yarn sets

The aim of this study was to understand the failure mechanism of two dimensional dry fabric structure considering yarn sets and interlacements. For this purpose, data generated on air-entangled textured polyester woven fabric under the simple tensile load and analyzed by developed regression model. The regression model showed that warp and weft directional tensile strengths of satin fabric were higher than those of plain and rib fabrics in unravel sample. This might be related to the number of interlacements of the fabrics. There was not a considerable difference between warp directional tensile strength of ravel and unravel satin fabrics, whereas weft directional tensile strength of ravel satin fabric decreased rapidly with respect to its unravel form. The satin fabric showed the highest warp directional tensile strength among the others. The lowest weft directional tensile strength was received from ribs fabric. In semi-ravel sample, all fabrics showed low warp and weft directional tensile strength values except in plain fabric. Warp directional tensile elongation of plain fabric was the highest in unravel sample. Satin fabric showed the highest warp directional tensile elongation in the ravel sample. Warp directional tensile elongations of all the fabrics in the semi-ravel sample became low. Weft directional tensile elongation of satin fabric was the highest in unravel sample. In addition, satin and plain fabrics showed the highest weft directional tensile elongations in the ravel sample. Weft directional tensile elongations of all the fabrics in the semi-ravel sample became low except in ribs fabric.     

A study on chitosan modification of polyester fabrics by atmospheric pressure plasma and its antibacterial effects

Chitosan is a natural nontoxic biopolymer used widely in various fields due to the antimicrobial activities. In this study, the properties of polyester fabrics grafted with chitosan oligomers/polymers after being activated by atmospheric pressure plasmas were evaluated. The antibacterial effect was most evident when the surface of fabrics was activated by atmospheric pressure plasma for 60 to 120 seconds and grafted with chitosan oligomers. The modified fabrics also exhibited good biocompatibility. This process can be applied to a large area and used to produce antibacterial polymer fibers.     

Ferulic and p-coumaric acids extraction by alkaline hydrolysis of brewer's spent grain

This work deals with the alkaline hydrolysis of brewer's spent grain (BSG) for the extraction of ferulic and p-coumaric acids, compounds of considerable interest for applications in the food, health, cosmetic, and pharmaceutical industries. A 2³ full factorial design with three replicates at the center point was used to investigate the simultaneous effects of the variables: NaOH concentration (1.0, 1.5 and 2.0%, w/v), temperature (80, 100 and 120 °C), and reaction time (30, 60 and 90 min), on the alkaline hydrolysis. The assays were performed using a solid:liquid ratio of 1:20 (w/w). The Student's t-test revealed a positive influence (p < 0.05) of all the studied variables on the ferulic and p-coumaric acids extraction from BSG. Linear models were well fitted (R² > 0.90) to the experimental data to describe the extraction of these acids as a function of the operational variables employed. The best alkaline hydrolysis conditions consisted in using a 2% NaOH concentration, at 120 °C for 90 min. Under these conditions, a liquor containing 145.3 mg/l ferulic acid and 138.8 mg/l p-coumaric acid was obtained. These values corresponded to 9.65 mg ferulic acid and 9.22 mg p-coumaric acid per gram of solubilized lignin.     

Changes of pulling-out length and shrinkage ratio in polyester/spandex power net warp knitted fabrics

Power net fabric is one of the highly extensible two-way fabrics. Power net structure shows special characteristics in the wearing of final functional clothes. This research evaluated effects of treatment temperature on proportional extensibility and shrinkage ratio of spandex at a given wale length. As treatment temperature increased, extensibility increased proportionally to the standard length of the sample and the shrinkage ratio in the direction of course and wale increased. The pulling-out length increased proportionally to the standard length of the sample. However it was affected by the effect of treatment time and temperature due to the thermal properties of spandex filament yarn.