Kyung Wha Oh

Automatic Recognition of Fabric Weave Patterns by Digital Image Analysis

By using computer image processing and analysis, a system to detect both weave patterns and yarn color designs is developed in this study. The image of a woven fabric is captured by a Hitachi color CCD camera and converted into digital data by a Targa+32 board. Two images—transmitted and reflected—are used to detect weave patterns. From the transmitted images, warp and weft cross points and the sizes of the yarns are determined by analyzing gray value changes in both horizontal and vertical directions. Then the warp and weft crossed states are determined by analyzing the normalized aspect ratio of an ellipse-shaped image at crossed points of the fabric. Furthermore, from reflected images, the total number of yarn colors and their arrangements in the fabric are determined. An HSV color model differentiates or groups similar yarn colors. Consequently, the system allows the weave pattern, either colored or solid, and the color design of a fabric to be correctly recognized.By using computer image processing and analysis, a system to detect both weave patterns and yarn color designs is developed in this study. The image of a woven fabric is captured by a Hitachi color CCD camera and converted into digital data by a Targa+32 board. Two images—transmitted and reflected—are used to detect weave patterns. From the transmitted images, warp and weft cross points and the sizes of the yarns are determined by analyzing gray value changes in both horizontal and vertical directions. Then the warp and weft crossed states are determined by analyzing the normalized aspect ratio of an ellipse-shaped image at crossed points of the fabric. Furthermore, from reflected images, the total number of yarn colors and their arrangements in the fabric are determined. An HSV color model differentiates or groups similar yarn colors. Consequently, the system allows the weave pattern, either colored or solid, and the color design of a fabric to be correctly recognized.

Electrically conductive textiles by in situ polymerization of aniline

Two methods of obtaining electrically conductive fabrics by in situ poly- merization of aniline were compared. Conductive fabrics were prepared by immersing the nylon 6 fabrics in 100% aniline or an aqueous hydrochloride solution of aniline followed by initiating successive polymerization in a separate bath (DPSB) or in a mixed bath (DPMB) of oxidant and dopant solution with aniline. In each case, the polymerization conditions were optimized to obtain the maximum quality of polyaniline (PAn) on the fabrics. The higher conductivity of composite fabrics, whose value reached up to 0.6 3 10 21 s/cm, was obtained by the DPMB process. Moreover, this method induced the least decrease in the degree of crystallinity as compared to the DPSB process. The serviceability of the PAn-nylon 6 composite fabrics was also evaluated. No significant changes in the conductivity were observed after abrading the composite fabrics over 50 cycles and multiple acid and alkali treatment. The stability of conduc- tivity was slightly decreased by less than 1 order after exposure to light for 100 h, but it was significantly decreased after washing with detergent.

Automatic Structure Analysis and Objective Evaluation of Woven Fabric Using Image Analysis

An automatic fabric evaluation system has been developed to automatically analyze the structure of woven fabric and objectively evaluate fabric quality. Fabric images are captured by a CCD camera and preprocessed by Gaussian filtering and histogram equalization. Fabric construction parameters such as count, cloth cover, yarn crimp, fabric thickness, and weight per unit area are measured automatically from planar and cross-sectional images of woven fabric with image processing and image analysis. Results obtained with the system show good correspondence with experimental values. In order to evaluate the quality of woven fabric, defects such as slubs or missing picks are detected successfully from defect images, and the uniformity of yarn spacing and orthogonality of the yarn intersecting angle are determined from normal fabric images. The coefficients of variation of yarn spacing and the yarn intersecting angle are measured quantitatively so that quality can be compared using these values.

Zein/cellulose acetate hybrid nanofibers: Electrospinning and characterization

Protein based scaffolds are preferred for tissue engineering and other biomedical applications owing to their unique properties. Zein, a hydrophobic protein, is a promising natural biodegradable polymer. However, electrospun structures prepared from Zein have poor mechanical and wetting properties. Cellulose acetate (CA) is an economical, biodegradable polymer having good mechanical and water retention properties. The aim of present study was to fabricate a novel material by electrospinning Zein/CA blends. A series of Zein/CA hybrid nanofibers were electrospun and characterized. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATRFTIR) spectrum showed the characteristic peaks of both Zein and CA, and was composition dependent. The X-ray photoelectron spectrometry (XPS) curves of Zein/CA blends demonstrated a similar profile to that of pristine Zein nanofibers. Thermogravimetric analyser (TGA) studies confirmed that the Zein/CA hybrid nanofibers have a higher degradation temperature and better thermal stability than pristine Zein nanofibers. The glass transition temperature (Tg) of Zein/CA hybrid nanofibers was also increased in comparison to pure Zein nanofibers as revealed by differential scanning calorimetry (DSC). Zein/CA hybrid nanofibers have hydrophilic surface character as revealed by water contact angle (WCA) analysis. SEM imaging showed bead free morphology of the electrospun nanofibers. The average nanofiber diameter decreased for Zein/CA blends with increasing CA composition. The electrospun Zein/CA hybrid nanofibers may be used for tissue engineering scaffolds and for other biomedical materials.

Preparation and characterization of cotton fabrics with antibacterial properties treated by crosslinkable benzophenone derivative in choline chloride-based deep eutectic solvents

Cotton fabrics with antibacterial properties were prepared by the treatment with 3,3′4,4′-benzophenone tetracarboxylic dianhydride (BPTCD) in a combined process of shaking immersion in dyeing machine and pad-dry-cure. Environmentally-benign choline chloride (ChCl)-based deep eutectic solvents (DESs) were mainly examined as treatment media instead of using organic solvent. The results revealed that cotton fabrics treated with BPTCD in urea-ChCl DES showed a strong ester carbonyl peak in fourier transform infrared (FTIR) analysis, indicating fixation of BPTCD on cotton cellulose. Detailed characterizations of the BPTCD-treated cotton were carried out by FTIR, thermogravimetric analysis, scanning electron microscopy, dye staining, and evaluation of hydrophilicity and strength. The treated fabrics demonstrated a high level of antibacterial characteristics before and after UV irradiation. This indicated that addition of ChCl could enhance antibacterial activity of cotton before UV irradiation. Therefore, use of ChCl-based DES along with BPTCD incorporation provided environmentally-acceptable and economically-feasible treatment process for preparation of novel antibacterial cotton.

Water absorption and mechanical properties of pile-knit fabrics based on conjugate N/P microfibers

The effect of chemical splitting on the water absorption and mechanical properties of a split-type nylon/polyester (N/P) microfiber pile knit is investigated under various alkaline hydrolysis treatment conditions. Weight loss of the hydrolyzed pile knit increases as hydrolysis time, temperature, and concentration of sodium hydroxide increase. Areal density decreases with increased weight loss. Maximum water absorption (%) is 28.1 % of weight loss. In terms of mechanical properties measured by KES-FB, deformation of the shape of the knit is easy due to decreased tensile strength. Bending and shearing values diminish, which leads to increased drapability and flexibility. Surface properties vary with changes in weight loss. The morphological study reveals that the fineness of the split polyester microfibers decreases with increased weight loss.The effect of chemical splitting on the water absorption and mechanical properties of a split-type nylon/polyester (N/P) microfiber pile knit is investigated under various alkaline hydrolysis treatment conditions. Weight loss of the hydrolyzed pile knit increases as hydrolysis time, temperature, and concentration of sodium hydroxide increase. Areal density decreases with increased weight loss. Maximum water absorption (%) is 28.1 % of weight loss. In terms of mechanical properties measured by KES-FB, deformation of the shape of the knit is easy due to decreased tensile strength. Bending and shearing values diminish, which leads to increased drapability and flexibility. Surface properties vary with changes in weight loss. The morphological study reveals that the fineness of the split polyester microfibers decreases with increased weight loss.

Nonformaldehyde Crease-Resistant Finishing of Ramie with Glyoxal in the Presence of a Swelling Agent

The feasibility of glyoxal treatment for ramie fabric in the presence of a swelling agent is studied. Adding polyethylene glycol (PEG) 600 or a higher molecular weight PEG to the glyoxal finishing bath provides an optimum balance between the wrinkle recovery angle and strength retention by maximizing ramie swelling during the crosslinking reaction. Adding PEG also increases the water of imbibition, moisture regain, whiteness index, and color strength of treated ramie fabrics. The durability of glyoxal finished fabric in the presence of PEG is also acceptable during multiple launderings. Therefore, glyoxal treatment with PEG can be used for crease-resistant finishing of ramie and ramie-blended fabrics to obtain superior performance properties.

Effect of Abrasion and Absorbed Water on the Handle of Nonwovens for Disposable Diapers

Among the components of a disposable diaper, the top layer that comes into direct contact with the infant’s skin is usually made of a nonwoven fabric. Therefore, the mechanical and surface characteristics of the nonwovens are important for the health of the baby’s skin. In this study, we explored the mechanical and surface properties of some hygienic nonwoven fabrics that are used as the top layer and investigated consumers’ preferences concerning these nonwovens. The variations in their properties with increasing abrasion cycles and in wet conditions were also examined. The hygienic nonwoven fabrics examined in this study were cotton spunlace, tencel spunlace, polypropylene (PP) thermal bonding and PP Thru-air bonded carded web (TABCW). The surface of PP nonwoven fabrics were treated with surfactant to obtain the required hydrophilic properties. From the results of KES-F analysis, it was found that PP TABCW had a low friction coefficient and showed little change in surface properties with increasing number of abrasive cycles, and moreover, it revealed superior quick-drying characteristics. However, the consumers showed a somewhat higher preference for cellulose spunlaces in comparison with surfactant-treated PP nonwoven fabrics. On the other hand, although they showed excellent absorption characteristics, the spunlace-type nonwovens made with cellulose tissue displayed higher surface friction coefficients and relatively low abrasion strength, especially in wet conditions.

Effect of castor oil/polycaprolactone hybrid polyols on the properties of biopolyurethane

Organic solvent soluble castor oil/polycaprolactone diol (PCL) based polyurethane for artificial leather was prepared by a one-step polymerization with 4,4′-diphenylmethane diisocyanate (MDI) at different castor oil contents. The PCL and MDI acted as soft and hard segments, respectively, and the castor oil acted as a dendritic point in the castor oil/PCL based polyurethane structure. The tensile properties and shape memory of castor oil/PCL based polyurethane were enhanced remarkably, compared with the PCL based polyurethane because of the increased hard segment portion and crosslinking density by the three urethane bonds formed per molecule in the castor oil/PCL mixed system. The dynamic mechanical analysis showed that the storage modulus of castor oil/PCL based polyurethanes increased with increasing castor oil content. In the enzymatic degradation test, castor oil/PCL based polyurethane degraded faster than conventional petroleum based polyurethane. This research suggests the potential to use the castor oil/PCL based polyurethane as a biobased coating materials.

Thermal Stability of Conductive Polyaniline-Nylon 6 Composite Fabrics Doped by a Mixture of Protonic Acids:

We have studied the thermal stability of conductive polyaniline (PANI)-nylon 6 composite fabrics doped by a mixture of hydrochloric acid (HCl) and various organic aryl sulfonic acids such as benzenesulfonic acid (BSA), dodecylbenzenesulfonic acid (DBSA), and ρ-toluenesulfonic acid (TSA). Conductive fabrics are prepared by immersing the nylon 6 fabrics in an aqueous hydrochloride solution of 0.5M aniline and by initiating successive polymerization with an oxidant in various doping solutions. When the same molar ratio of HC1 in the diffusion bath and various protonic acids in the polymerization bath are mixed and serve as the dopant for polyaniline, the highest fabric conductivity is obtained with HC1/BSA, and HC1/TSA, HC1/DBSA, and HC1/HC1 in decreasing order. The conductivity of all doped PANI-nylon 6 composite fabrics decays at elevated temperatures in air. Among the various dopants, HC1/DBSA shows the best thermal stability, followed by HC1/TSA > HC1/BSA > HC1 in decreasing order.