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.     

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.     

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.     

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.     

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.     

Cutinase treatment of cotton fabrics

Our study proposes an enzymatic scouring method for cotton fabrics using the enzyme cutinase. We established cutinase treatment conditions for cotton fabrics from their relative activity at different pH levels, temperatures, enzyme concentrations, and treatment times. Weight loss, moisture regain, K/S value, tensile strength, and SEM micrographs of cotton fabrics were analyzed. We determined the optimum cutinase treatment conditions to be as follows: pH of 9.0, temperature of 50°C, cutinase concentration of 100 %, and a treatment duration time of 60 min. We discovered that this cutinase treatment hydrolyzed the cuticle of cotton fabrics. The cutinase treatment did not decrease the moisture regain and the K/S value. The optimum concentrations of Triton X-100 and calcium chloride, which were used as auxiliaries for cutinase treatment, were found to be 0.5 % (v/v) and 70 mM, respectively. Some cracks were observed on the surface of the cotton fibers; however, the tensile strength did not decrease.     

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.     

Development of superhydrophobic polyester fabrics using alkaline hydrolysis and coating with fluorinated polymers

Alkaline hydrolysis is one of the most classic fiber finishing methods, however, its potential as tuning surface superhydrophobicity in mass scale has not been studied much. In this research, fine roughness was formed on the polyester fiber surfaces by alkaline hydrolysis at room temperature and fluorinated polymer mixtures were further coated. The developed superhydrophobic fabrics were evaluated in terms of structural changes, mechanical properties, surface hydrophobicity, and permeability for practical applications. As alkaline hydrolysis treatment time increased, surface roughness was increased as a lot of nano-craters were generated with the decrease of fabrics weight and tensile strength as well. As air pockets formed through nano-craters on the fiber surfaces, static contact angle increased, and shedding angle tended to decrease. In this study, the sample treated with alkaline hydrolysis for 20 minutes showed the highest static contact angle of 167.8±1.3° and lowest shedding angle of 4.4±2.3°. Considering tensile strength loss, however, the 15-minute alkaline hydrolyzed fabrics which showed static contact angle of 162.2±2.7° and shedding angle of 8.8±0.2° was selected as the optimal condition for practical application. The newly developed superhydrophobic fabrics were found to have higher water vapor and air permeability than those of untreated samples. At the same time, fluoropolymer coating played a certain role for tensile strength and water vapor permeability demonstrating the importance of understanding and designing proper fluorinated-compound treatment processes.     

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.     

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 enzymatic treatment of polyester fabrics by lipase from <Emphasis Type="Italic">Porcine Pancreas</Emphasis>

The aim of this study was to provide the optimum condition for improving the hydrophilicity of PET fabrics by lipase treatment. The lipase hydrolytic activity, moisture regain, and wettability of PET fabrics were measured at different pH, temperature, reaction time, and concentration. The hydrolytic activity of lipase was evaluated by the number of carboxylic groups, using the titration method. Each treatment condition was controlled by measuring the hydrolytic activity, moisture regain, and wettability. The lipase treatment condition was controlled at pH 7.5, temperature 40 °C, treatment time 90 min, and concentration 6.25 g/l. Lipase treatment was an effective method to improve the moisture regain and wettability of PET fabrics because lipase hydrolysis formed hydrophilic groups on the surface of PET fabrics. The surface of the lipase-treated PET fabrics showed cracks and voids, largely responsible for the increase in the PET’s water-related properties. The nitrogen contents of the lipase-treated PET fabrics were measured at only 0.072 %. Thus, the improvement of the surface wettability of the lipase-treated PET surface was associated with the hydrolytic action of lipase rather than with protein absorption.     

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.     

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.     

Assessment of color strength and color difference values of polyester fabrics containing continuous weft yarns after abrasion

This paper assesses the color difference and color strength values (K/S) obtained for eight disperse-dyed polyester fabric samples with different fabric construction parameters (weft yarn type, weft yarn count, weft density and fabric weave) after four sets of abrasion cycles. Warp yarn type and count, warp density, and warp yarn twist are the same for all fabrics. Fabric samples are dyed in a commercial red disperse dye (C.I. Disperse Red 74:1) and four different abrasion cycles (2500, 5000, 7500, 10000) are used. TheK/S values of the abraided fabrics and color difference values between the control fabric (dyed but not abraided) and abraded fabrics are calculated. The main differences in theK/S and color difference values are observed between 0–2500 abrasion cycles. The high tenacity of the polyester fibers and continuous polyester yarns causes some fuzz but no pilling formation on the fabric surface that lead to increasedK/S values and color differences. Fiber dullness, yarn thickness, yarn density and fabric weave are concluded to have different effects on the appearance after abrasion.     

Application of one-quarter fractional and full factorial design to study set mark phenomenon of multifilament polyester fabrics

Set marks are fabric defects in weft direction which are caused by an interruption of the weaving process. In this study, based on one-quarter fractional factorial design, among eight parameters of weaving machine, i.e. horizontal and vertical position of back rest roller, horizontal position of warp stop motion, shed crossing degree, shed crossing point position, warp tension, stoppage position of machine, and stoppage time, four most effective parameters was determined. These parameters were stoppage position of machine, vertical position of back rest roller, shed crossing point, and horizontal position of warp stop motion. Then using full factorial design effectiveness of these parameters was evaluated statistically at 99 % confidence level and effect of them on set mark studied in detail. Statistical evaluations showed that the stoppage position of machine was the most effective parameters on intensity of set mark of multifilament polyester fabric. A specific image capturing device for using on weaving machine based on CCD camera was designed. Image processing technique was used to measure the pickspacing in stop zone objectively. Five picks before and five picks after stoppage was considered as stop zone and the standard deviation of pickspacing was used as a criterion which interpret this defect. Dynamic loading of warp yarns were execute to evaluate the relaxation behavior of polyester multifilament warp yarns.     

A study of comfort performance in cotton and polyester blended fabrics. I. Vertical wicking behavior

Vertical wicking model was developed based on Darcy’s law. In the model, permeability coefficient, capillary pressure and fabric thickness were used as the key parameters to describe wicking behavior. For the simulation and test, fiber type and fabric structure were chosen as variables. In a highly porous knit fabric, gravitational effect during the wicking process was significant. The higher the capillary pressure was, the higher was the wicking rise. Surface wetting tension, i.e., the specific fluid affinity of material, was newly defined to characterize different capillary pressures in various types of fabric structures. The model, the methodology and the results could provide an insight into fabric design to produce fabric with an optimum wicking performance.     

Analysis and off-axis tensile characterization of air-entangled textured polyester woven fabrics depending on unit cell interlacing frequency

The aim of this study is to analyze and determine the off-axis tensile properties of air-entangled textured polyester fabrics based on unit cell interlacing frequency. For this purpose, continuous filament polyester air-entangled textured yarn was used to produce plain, ribs and satin woven fabrics. The fabrics were cut from the warp direction (0°) to weft direction (90°) at every 15° increment, and tensile tests were applied to those of the off-axis samples. The strength and elongation results were introduced to the statistical model developed, and regression analyses were carried out. Hence, the effects of off-axis loading and interlacement on the directional tensile properties of the fabric were investigated. The regression model showed that off-axis loading influences fabric tensile strength. On the other hand, interlacement frequency is the most important factor for fabric tensile elongation. The results from the regression model were compared with the measured values. This study confirmed that the method used in this study as can be a viable and reliable tool. Future research will concentrate on multiaxially directional fabric and the probability that it will result in homogeneous in-plane fabric properties.