Kit-Lun Yick

Structures and Properties of Wet Spun Thermo-Regulated Polyacrylonitrile-Vinylidene Chloride Fibers

Thermo-regulated polyacrylonitrilevinylidene chloride (PAN/VDC) fibers containing 4-40 wt.% of micro phase-change materials (microPCMs) were wet-spun. In this study, fibers containing less than 30 wt.% of microencapsulated n-octadecane were spun smoothly. The structures and properties of the fibers were investigated by using Fourier transform infrared, scanning electron microscopy, differential scanning calorimetry, wide-angle X-ray diffraction, dynamic mechanical analysis and thermogravimetric analysis, etc. The microcapsules were intact and evenly distributed inside the polymer matrix. The tensile strengths of the fibers with titers in the range of 1.9 to 10.9 dtex were 0.7 to 2.0 cN/dtex. The elongation of the fibers was approximately 7%. The heat-absorbing and heat-evolving temperatures of the fibers increased slightly with the increase of the content of microPCMs. The enthalpy of melting or enthalpy of crystallization of the fiber containing 30 wt.% of microPCMs was approximately 30 J/g, and the enthalpy of melting or enthalpy of crystallization increased steadily as the content of microPCMs increased. The modulus of the fiber decreased with the increase in the amount of microPCMs in the fiber. The glass transition temperature of the fiber was 89-108°C which decreased with the increase of the content of microPCMs, and the melting and decomposing temperatures of the fiber were approximately 190 and 220°C, respectively. The fibers had a limited oxygen index value that was higher than 25% and were permanently in flame retardation.

Application of the Box-Behnken design to the optimization of process parameters in foam cup molding

Currently, foam molding technologies are widely adopted for most bra styles, which demonstrate the incomparable advantages in the contemporary intimate apparel industry. The determination of proper molding conditions, such as molding temperatures and length of time on the basis of cup sizes and styles, is crucial in achieving the required cup shape with high stability, which is regarded as the most challenging part of the molded bra making process. To determine the optimal process parameter settings, numerous process trials are generally required to evaluate the molding variables and their interactions. This study proposes a novel systematic methodology to identify the optimal molding process parameters based on design of experiment (DOE) and a parameterization-based remesh method to evaluate the 3D shape conformity of molded cups. By solving the regression equation obtained from a Box-Behnken design (BBD) and analyzing the response surface plots, the results prove that molding temperature has greater influence than the length of the dwell time on the 3D shape conformity of molded cups. The optimal molding conditions can be determined for the cup depths of different sized mold heads, which are validated by the experimental results.

Subjective and objective evaluation of men’s shirting fabrics

Reports a survey of fabric handle preferences for a range of 50 men’s shirting materials. A total of 199 judges were divided into two panels according to their experience in the textile and clothing industry. Low levels of agreement were found which signify the errors inherent in subjective assessment of fabric handle. The analysis was extended to include fabric assurance by simple testing (FAST) data on the mechanical properties of these fabrics in order to establish whether there was any relationship existing between the judges’ preferences and the fabric mechanical parameters. Highlights shear rigidity, formability and bending rigidity as the most influential properties for the determination of fabric total hand value (THV). Moreover, establishes a validated THV equation to predict fabric handle assessment by using objective data. Demonstrates that the mean of the assessment and a substantial amount of individual subjective handle assessment can be explained by the model.

Comparison of Mechanical Properties of Shirting Materials Measured on the KES-F and FAST Instruments

This study compares the test results of the FAST system (fabric assurance by simple testing) with those of the KES-F (Kawabata evaluation system for fabrics) for two series of twenty-two shirting materials in terms of their low-stress fabric mechanical properties of bending, shear, and tensile deformation. The first series of eighteen shirting fabrics, ranging in weight from 96 to 170 g/m2, was sampled from a leading Hong Kong shirt manufacturer. The second series of four denim shirting fabrics, ranging in weight from 199 to 217 g/m 2, was later included to test the validity of extrapolating the relationships observed for the first series of eighteen shirting materials. Despite some considerable differences in the measurement principles of the two testing systems, there are highly significant correlations between the parameters obtained from the test results of the two systems.

Parametric design and process parameter optimization for bra cup molding via response surface methodology

Seamless and traceless undergarments have rendered foam sheet molding as an important manufacturing technique for the intimate apparel industry. Seamless bra cups are made by one-step forming technology. The three-dimensional (3D) cup shape is formed by using high temperatures and pressures with flexible polyurethane foams. Nevertheless, the mold head design process and control of the bra cup molding process are highly complicated and error prone. There is limited knowledge about the effects of foam properties, molding parameters and foam cup geometric parameters on molding process optimization. This research presents a response surface methodology as the approach for parametric design and process parameter optimization of bra cup molding. The proposed approach integrates 3D scanning via reverse engineering, parameterized-based remeshing and registration algorithm, non-linear mathematical prediction models for cup shape conformity, a model of foam shrinkage and example-based bra cup design and grading to optimize the bra cup development and production process. The experimental results show that this method is highly effective and more timesaving in the design and development of new products, as well as providing consistent quality control of the bra cup molding process.

Prediction of fabric tension and pressure decay for the development of pressure therapy gloves

Pressure garments are commonly used in the treatment of hypertrophic and deformed scars. Pressure monitoring is crucial for effective pressure therapy. A new method is proposed to predict the amount of pressure acting on skin induced by pressure therapy gloves on the basis of hand curvatures extracted from three-dimensional hand images. The non-linear tensile properties of seven types of fabrics with various structures and their tension decay in relation to prolonged usage and reduction factors are examined. By taking into consideration the fabric elongation when the gloves are worn, a total of 36 pressure gloves are tailor-made by using three reduction factors. Based on the fabric tensile behavior, the corresponding glove pressure is predicted by the local strain, fabric tension per unit length and curvature of hand surface. No statistical difference at significance level of 0.05 is found between the predicted glove pressures and the measured values. In the measuring points on the dorsum of the hand, except the metacarpal site, the root mean square error ranges from 0.79 to 1.18 kPa. The investigation confirms that all pressure gloves lose tension and, therefore, pressure delivering ability upon repeated uses. It is also revealed that the pressure measuring positions and their corresponding curvature and geometry changes caused by hand movements and postures are closely associated with interfacial pressure delivered by the glove.

Exploring use of warp-knitted spacer fabric as a substitute for the absorbent layer for advanced wound dressing

Wound management has become more sophisticated as modern wound dressings now focus more on providing an optimal microclimate for wound healing. As a novel three-dimensional textile material, warp-knitted spacer fabrics are versatile enough to meet special requirements when their parameters are changed. This paper reports on an experimental study on the required physical properties of warp-knitted spacer fabrics that can be developed as an absorbent layer for advanced wound dressing. Three types of wound dressings available on the market have been chosen that are especially used for burns and ulcers, as they are designed to provide good absorbing of extrudes and a cushioning effect. The physical properties of spacer fabrics, including air permeability, thermal conductivity, water vapor permeability, absorbency and compression, are evaluated and compared with those of existing wound dressings. The results show that the air and water vapor permeabilities and the thermal conductivity of warp-knitted spacer fabrics are competitive enough to prove that spacer fabrics can also provide a good ventilated environment for wound healing. Their good compressional resistance and compressional resilience indicate that warp-knitted spacer fabrics can provide good protection as wound dressings. Although their absorbency is only somewhat better than some of the wound dressings, they are also good for wounds with no heavy extrudes.

The application of fabric objective measurement in shirt manufacture

Evaluates the mechanical properties of 60 different shirting materials: fabric extensibility, formability, shear rigidity, bending rigidity, relaxation shrinkage, and hygral expansion by the adoption of the fabric assurance by simple testing (FAST) system. Investigates manufacturing processes comprising spreading, cutting, sewing, handling, pressing and packaging and correlates the measured properties of the shirting fabric with their actual performance during making up. Claims this overall evaluation of respective fabric performance enables manufacturers to identify the range of mechanical properties ideal for high‐quality shirt production. Adds that specific manufacturing instructions can be prepared, based on the results of fabric property evaluation, for fabrics which tend to present difficulties in production. Points out that these can considerably expedite the manufacture of garments, avoiding the alternative – expensive “trial and error” – solution to problems.

New Methods for Evaluating Physical and Thermal Comfort Properties of Orthotic Materials Used in Insoles for Patients with Diabetes

Orthotic insoles are commonly used in the treatment of the diabetic foot to prevent ulcerations. Choosing suitable insole material is vital for effective foot orthotic treatment. We examined seven types of orthotic materials. In consideration of the key requirements and end uses of orthotic insoles for the diabetic foot, including accommodation, cushioning, and control, we developed test methods for examining important physical properties, such as force reduction and compression properties, insole-skin friction, and shear properties, as well as thermal comfort properties of fabrication materials. A novel performance index that combines various material test results together was also proposed to quantify the overall performance of the insole materials. The investigation confirms that the insole-sock interface has a lower coefficient of friction and shearing stress than those of the insole-skin interface. It is also revealed that material brand and the corresponding density and cell volume, as well as thickness, are closely associated with the performance of moisture absorption and thermal comfort. On the basis of the proposed performance index, practitioners can better understand the properties and performance of various insole materials, thus prescribing suitable orthotic insoles for patients with diabetic foot.

Effects of different heel angles in sleep mode on heel interface pressure in the elderly.

BACKGROUND The heels are one of the most common sites of pressure ulcers, and the incidence rate in the elderly aged 70 years or older is high. Although there is literature on heel interface pressure, the heel interface pressure of the elderly in different postures has not yet been explored, which will be investigated in this study, as well as the effects of different foot positions. Their skin conditions will also be examined. METHODS Twenty-five females and twenty-six males, 70 years old or older, are evaluated while lying down, with only their naked foot in its natural position on a mattress, as well as placed on a standard or pressure-relieving mattress in different positions. The moisture, sebum content, and elasticity of the skin of the heel are tested. FINDINGS The heel of most of the participants is positioned at a 60°-69° or 90°-99° angle to the support surface. The heel interface pressure is the greatest when the foot is upright. The age, weight, and body mass index have no significant impacts. The moisture and sebum content are extremely low while elasticity is normal. INTERPRETATION The relaxed position of the foot is in neutral external rotation and upright positions. A greater amount of pressure is experienced when the foot is upright. The pressure-relieving mattress is more effective for reducing heel pressure but may not apply to all cases. Finally, the skin of the heel is dry and lacks sebum, which implies greater risk of developing heel sores.