Gilsoo Cho

Thermal storage/release, durability, and temperature sensing properties of thermostatic fabrics treated with octadecane-containing microcapsules

To develop a thermostatic fabric, a 100% polyester fabric is treated with octadecane- containing microcapsules by a knife-over-roll coating process. The amount of heat content increases as the concentration of microcapsules increases. and it decreases as the temper ature and time increase. The surfactant treatment at a given microcapsule concentration increases the heat content of the treated fabrics about 56-94%. The durability of the coated microcapsules lasts for about ten launderings. The treated fabric becomes stiffer and less smooth, soft, and full than the untreated fabric, as shown by KES measurements. Wear trials with the untreated and treated garments in a conditioned environment confirm the temperature sensing properties of treated garments. The cooling effect from thermal storage of the octadecane-containing microcapsules is revealed by results showing that the changes in the mean skin and microclimate temperature with the treated garment are less than for those wearing the untreated garment.

Antimicrobial and Blood Repellent Finishes for Cotton and Nonwoven Fabrics Based on Chitosan and Fluoropolymers

In order to impart barrier properties against microorganisms and blood to 100% cotton fabrics and 55/45% woodpulp/polyester spunlaced nonwoven fabrics, samples are treated with chitosan and fluoropolymers using the pad-dry-cure and pad-cure meth ods, respectively. Antimicrobial activity of the samples is analyzed quantitatively by measuring the number of colonies of Staphylococcus aureus. Blood repellency is as sessed with an impact penetration test using synthetic blood. Laundering durability of the finishes is measured, and scanning electron microscopy is used to evaluate changes in the fabric surfaces. To investigate the effect of finishing on the hand and air per meability of fabrics, the mechanical properties of the samples are measured by the KES-FB system. Samples treated only with chitosan show a high reduction rate in the number of colonies. Dual finished specimens treated with 1.1 % chitosan concentration also maintain over 90% reductions in the number of colonies. The blood repellency of dual finished nonwoven fabrics is superior to that of dual finished cotton. Dual finished cotton fabrics exhibited durable antimicrobial activity with repeated laundering. As regards mechanical properties, bending rigidity and shear rigidity increase when cotton and nonwoven fabrics are treated only with chitosan, but these properties decrease after the fluoropolymer treatment. Air permeability of the specimens decreases slightly after the dual finish.

Thermal Storage/Release and Mechanical Properties of Phase Change Materials on Polyester Fabrics

Melamine formaldehyde microcapsules containing octadecane are synthesized by the interfacial polymerization method, and the size, shape, and thermal storage/release prop erties of the synthesized microcapsules are analyzed by FTIR, SEM, and DSC. Polyester fabrics are then coated with the microcapsules under various conditions of concentration and time/temperature by the knife-over-roll (KOR) and screen printing (SP) methods. The thermal, mechanical, and physical properties of the untreated and treated fabrics are evaluated to identify the best adhesive method. The mean diameter of the microcapsules ranges from 1 to 1.5 μm, and their shapes are almost spherical. Under the optimum treatment concentration, temperature, and time, thermal properties after five launderings decrease rapidly, and the bending and shear rigidities of the KOR fabrics are higher than those of the sp fabrics. This means that fabrics coated by sp become less stiff and hard than those by KOR. sp fabrics exhibit higher air permeability and lower hygroscopic properties than KOR fabrics.

Performance Evaluation of Textile-Based Electrodes and Motion Sensors for Smart Clothing

Development of textile-based electrodes and motion sensors is one of the main issues of recent smart textile research utilizing electronic textiles. Electrocardiogram (ECG) electrodes have been developed by various textile technologies such as sputtering or electroless-plating on the fabric surfaces, and embroidering or knitting with stainless steel yarns. In addition, two types of motion sensors have also been developed using piezo-resistive textiles. They were fabricated by knitting and braiding. To examine the usability of the ECG electrode, waveforms of the conventional AgCl electrode, and the new electrodes developed in our lab were compared. It was found that electrodes using metallic embroidering are more efficient when its substrate was a metal blended fabric. The electrolessly Cu/Ni plated fabrics obtained the best conductivity in textile-based electrodes. The first motion-measuring textile-based sensor was used to predict and measure the changes in electric resistances that accompany the angle changes in the elbow joint. An advanced piezo-resistive textile by braiding showed more accurate resistance changes and also better durability. Changes in its electrical resistance were mapped to changes in its length extension. From the relationship between the extension and the electrical resistance, movement or posture of human body was detected.

Smart Clothing: Technology and Applications

With contributed chapters from various authors, this book covers the state of the art in smart clothing technology and applications, which includes textile-based keypads, transmission lines, sensors, and actuators. The authors address usability and human aspects relevant to the manufacture and sale of such products, and they detail the evolving and increasingly wide-ranging applications related to fields such as information, healthcare, and entertainment. Smart clothing technology topics addressed in the book include interface, communication, energy supply, data management, processors, and actuators. It also discusses packaging and interconnection, shape memory alloy, and design and modeling of electronic textile applications.

Thermal Properties and Physiological Responses of Vapor-Permeable Water-Repellent Fabrics Treated with Microcapsule-Containing PCMs

The purpose of this study is to develop a thermally adaptable, vapor-permeable water-repellent fabric. Vapor-permeable water-repellent fabrics with and without octade cane-containing microcapsules are obtained by a wet porous coating process. The thermal and physical properties of the octadecane-containing water-repellent fabrics (WR-PCM) are compared with the water-repellent fabric without octadecane (WR). The heat of fusion ( ΔHf ) of WR-PCM is 13.50 J/g at 29.06°C, and the heat of crystallization (ΔHf ) is 14.02 J/g at 11.45°C. The thermal properties remain relatively high after thirty launderings. WR-PCM shows a lower water vapor transmission value than WR and a lower air permeability. The water repellency of both fabrics is 100%, but the water resistance of WR-PCM decreases dramatically. In wear trials, the mean skin temperature and microclimate temperature of subjects wearing active wear made with WR-PCM are lower than those made with WR. But the microclimate humidity with WR-PCM has a higher rate than WR. Although the subjective sensations of WR and WR-PCM are not significantly different, WR-PCM is cooler and more comfortable than WR. The results of this study indicate that octadecane- containing microcapsules in water-repellent fabrics provide a cooling effect but sacrifice water resistance.

Fabric Sound Parameters and Their Relationship with Mechanical Properties

A number of woven fabrics are selected and their rustling sounds recorded. The spectra forms of these recorded sounds are then obtained by FFT. The level pressure of total sound (LPT) is calculated to evaluate sound loudness of specimens. Level range (ΔL) and frequency differences (Δf) are used to quantify sound spectra shapes. Linear trends in frequency with autoregressive errors are fitted to amplitude, and three coefficients (ARF, ARE, ARC) of the functions are obtained. KES-FB is used for mechanical property measure ments. Fabrics with the same fiber type show similar spectra shapes. Silk and polyester satin fabrics generally make the quietest sounds with low LPT, and they also have lower ARC values. Silk crepe de chine shows the highest level range value (ΔL). ARC values are significantly correlated to LPT. The sound parameters of each fiber group are predicted with some mechanical properties such as bending, shear, compression, and surface properties, fabric thickness, and weight by stepwise regressions.

Review and Reappraisal of Smart Clothing

Smart clothing is a “smart system” capable of sensing and communicating with environmental and the wearers conditions and stimuli. A comprehensive review is presented on the research and developments related to smart clothing including technology developments, human aspects in smart clothing, and the applications. Recent smart clothing technology can be summarized as a tendency toward textile-based technology for each component: interface, communication, data management, energy management, and integrated circuits. Human aspects in smart clothing, even though some areas were not fully covered, were dealt with in terms of usability, functionality, durability, safety, comfort, and fashion. General applications of smart clothing developed so far include bio-monitoring clothing, MP3 player-adopted clothing, and photonic clothing.

Clothing temperature changes of phase change material-treated warm-up in cold and warm environments

The purpose of this study was to investigate the appropriate amounts of phase change materials to give objective and subjective wear sensations. Vapor-permeable water-repellent fabrics with (WR-PCM) and without (WR) octadecane containing microcapsules were obtained by wet-porous coating process. Then, calculating the area of the WR-PCM treated clothes, we estimated the total calories of the clothing by multiplying the heat of fusion and heat of crystallization of PCM to the calculated area. Wear tests were conducted in both warm environment (30°C, 65 % RH) and cold environment (5°C, 65 % RH) with sports warm up style experimental garments made with WR and WR-PCM fabrics. Rectal, skin, and clothing microclimate temperatures, saliva and subjective evaluation measurements were done during the wear test. There was no difference of rectal and mean skin temperatures between WR and WR-PCM, but the clothing microclimate temperature of WR-PCM under warm environment was slightly lower than that of WR. In cold environment, WR-PCM showed much higher temperature than in WR. Saliva change did not appear between clothes, but did between two environments. Although subjective sensation between WR and WR-PCM was not significantly different, WR-PCM was rated as cooler than WR in warm environment and as warmer than WR in cold environment. The results of this study indicated that octadecane containing microcapsules in water-repellent fabric provide cooling effect.

Effect of a Dual Function Finish Containing an Antibiotic and a Fluorochemical on the Antimicrobial Properties and Blood Repellency of Surgical Gown Materials

In order to provide 100% cotton fabric and 55/45% woodpulp/polyester spunlaced nonwoven fabric with barriers against microorganisms and blood, samples are treated with gentamicin, a broad-spectrum antibiotic, and a fluorochemical compound using the pad-cure method. The antimicrobial activity of the samples is analyzed quantitatively by measuring the number of colonies of Klebsiella pneumonia, and qualitatively using the parallel streak method with Staphylococcus aureus. Blood repellency is assessed with spray and impact penetration tests using both synthetic and human blood. Samples treated with both the antibiotic and the fluorochemical (dual finish) show a high reduction rate in the number of colonies grown and clear zones of inhibition, which is the same as the antimicrobial properties of the samples treated with antimicrobial finishing agent only. The blood repellency of dual finished nonwoven fabrics is superior to that of dual finished cotton. The optimum concentration of the fluorochemical for synthetic blood repellency is 5% owf.