Bok Choon Kang

Dimensional Stability of Core Spun Cotton/Spandex Single Jersey Fabrics under Relaxation

In this study, dimensional stability of core spun cotton/spandex single jersey structures with high, medium and low tightness factors were experimented under dry, wet and full relaxation conditions. Results were compared with those for similar fabrics knitted from 100 % cotton. Course and wale spacing decreased and course, wale and stitch density increased with progression of relaxation and higher values reported with cotton/spandex structures. Course, wale and stitch density were linearly and positively correlated with loop length—1 or loop length— 2. Their correlation equations showed minimal intercepts under full relaxation and cotton/spandex exhibited lower intercepts. Dimensional constants (K-values) were predicted under 95 % significance level. Higher dimensional constants were reported with cotton/spandex single jersey structures than 100 % cotton and under full relaxation, cotton/spandex indicated better stable structures under full relaxation. From these experiments, it was confirmed that yarns with elastomeric components increase tightness factors, which have a significant effect on dimensional behaviors, giving better dimensional stability to single jersey fabrics. Yarn linear density was insignificantly changed during treatments.

Dimensional characteristics of core spun cotton‐spandex 1×1 rib knitted fabrics in laundering

Purpose – This paper aims to study the dimensional characteristics such as fabric density variations, dimensional constant parameters, linear and area dimensional changes and spirality angle variations of 1 × 1 rib knitted structures made from cotton‐spandex core spun yarns, under laundering regimes till 10th washing cycle.Design/methodology/approach – Samples of the above fabrics underwent dry, wet and full relaxation treatments and were subjected to standard atmospheric conditions prior to take the measurements. Washing was done in a front loading machine under normal agitation with machine 56 RPM. Each washing regime includes wash, rinse, spin, tumble dry steps. Washing temperature was set at 40°C and water intake for washing was 30 l and rinsed with cold water. 0.1 g/l standard wetting agent was used. The mass of the load was maintained constant to 3 kg to keep the material ratio as 1:10. Washing regimes were continued till 10th cycle.Findings – Cotton‐spandex rib structures came to a more stable stat...

The Effect of Etching on Low-stress Mechanical Properties of Polypropylene Fabrics under Helium/Oxygen Atmospheric Pressure Plasma

Polypropylene nonwoven fabrics were exposed to He/O2 atmospheric pressure glow discharge plasma. Surface chemical analysis and contact angle measurement revealed the surface oxidation by formation of new functional groups after plasma treatment. Weight loss (%) measurement and scanning electron microscopy analysis showed a significant plasma etching effect. It was investigated in low-stress mechanical properties of the fabrics using Kawabata Evaluation System (KES-FB). The surface morphology change by plasma treatment increased surface friction due to an enhancement of fiber-to-fiber friction, resulting in change of other low-stress mechanical properties of fabric.

Helium/oxygen atmospheric pressure plasma treatment on poly(ethylene terephthalate) and poly(trimethylene terephthalate) knitted fabrics: Comparison of low-stress mechanical/surface chemical properties

Helium-oxygen plasma treatments were conducted to modify poly(trimethylene terephthalate)(PTT) and poly(ethylene terephthalate) (PET) warp knitted fabrics under atmospheric pressure. Lubricant and contamination removals by plasma etching effect were examined by weight loss (%) measurements and scanning electron microscopy (SEM) analysis. Surface oxidation by plasma treatments was revealed by x-ray photoelectron spectroscopy (XPS) analyses, resulting in formation of hydrophilic groups and moisture regain (%) enhancement. Low-stress mechanical properties (evaluated by Kawabata evaluation system) and bulk properties (air permeability and bust strength) were enhanced by plasma treatment. Increasing interfiber and interyarn frictions might play important roles in enhancing surface property changes by plasma etching effect, and then changing low-stress mechanical properties and bulk properties for both fabrics.

A simplified optimization in cotton bale selection and laydown

We present a new approach to bale laydown grouping, which improves the laydown to laydown uniformities, compared to conventional approaches. In this approach, we use a frequency-relative picking method based on an HVI quality index for cotton bale selection and laydown formation. We demonstrate the effectiveness of this approach by computer simulation on real HVI data of 1500 cotton bales. Simulation results show that the proposed method significantly outperforms random picking.

Dimensional stability of cotton-spandex interlock structures under relaxation

In this study, dimensional characteristics of core spun cotton/spandex interlock structures with high, medium and low tightness factors were studied under dry-, wet-, and full relaxation conditions. Results are compared with those for similar fabrics knitted from 100 % cotton. Dimensional characteristics of samples of core-spun cotton/spandex and cotton are measured by considering the changing of course-, wale- densities and stitch densities under dry, wet and full relaxation conditions. Based on these data, dimensional constants (U-values) were predicted under 95 % significance level. Higher U-values are reported with cotton/spandex interlocks than 100 % cotton and under full relaxation, cotton/spandex shows the U-values with lesser CV%. Stitch density growth is linearly correlated with tightness factor for both interlock material structures. Excellent resiliency property of cotton/spandex yarns increases tightness factors at machine off state and during relaxation states. Cotton/spandex interlock structures show more prominent co-relationship with their tightness factors on their dimensional parameters.

Dimensional stability of single jersey fabrics of LincLITE® and conventional yarns. I

Dimensional constants (k values) of single jersey fabrics made from LincLITE® and conventional yarns are calculated under dry, steam, full relaxation treatments. Fabrics were made under different tightness factors such as high, medium and low with different twist factors, twist directions and feeder blending. LincLITE® yarns made to get soft and bulkier effects with yarn count of 39 tex and conventional yarns made into 39 tex and 48 tex yarn counts. Various effects on K values are analysed using correlation coefficients. K-values are increased with relaxation progression and have shown some differences between in LincLITE® and conventional fabrics, and feeder blended fabrics. Loop shape factor is highly affected by tightness factor, relaxation and feeder blending in LincLITE® fabrics, whereas twist factor not significantly effects on loop shape factor in conventional fabrics. Stitch density significantly increases with relaxation in conventional fabrics and no significant effect shows with LincLITE® fabrics.

Dimensional stability of single jersey fabrics of lincLITE® and conventional yarns. II. Fabric dimensional changes

Dimensional changes of single jersey fabrics made from LincLITE® and conventional yarns (39 tex and 48 tex) with different twist factors and fabric tightness factors are investigated under dry-, steam- and full- relaxation treatments. Results showed that linear and area shrinkages, fabric density and stitch density values were affected by tightness factors, relaxation treatment, yarn twist and feeder blending. Generally, higher length shrinkages and width increases were reported with LincLITE® and conventional fabrics. Tightness factors and twist factors significantly affected LincLITE® and insignificantly affected conventional fabrics in concern of change of shape and area shrinkages. Thus, fabric density values and reciprocal of stitch lengths showed linear correlations with intercepts, which decreased on full relaxation. Also, it showed higher regression correlation coefficient factors from LincLITE® and conventional fabrics.

Microscopic evaluation of commingling-hybrid yarns

Fibers made of elements such as carbon, aramid and glass have higher mechanical properties than other conventional textile fibers and they enable the production of light weight composites as end products. Furthermore, commingling hybrid yarns generally have a characteristic feature so that their components are distributed homogeneously enough over the yarn cross section. A normal air texturerising machine was modified to produce commingling hybrid yarns for test samples. Different process parameters were applied to produce the hybridized yarn samples. However, these process parameters turned out to have little effect on the filament distribution over the hybrid yarn cross section in terms of homogeneity. The analysis in this paper is focused on the pattern of mixing of filaments over a cross section of hybrid yarns according to different combinations of reinforcement and matrix filament yarns through microscopic view. The volume content of filament in hybrid yarn cross section was maintained at 50% for both reinforced and matrix, and the hybrid yarns count at 600 tex throughout experiments. It was concluded from the experiments that the diameters of reinforcement and matrix filaments have strong effects on the pattern of mixing of filaments over a cross section of hybrid yarns such that the hybrid yarns with more or less equal diameters of reinforcement and matrix filaments showed considerably even distributions over the hybrid yarn cross section.

An Analysis on the Tensile Strength of Hybridized Reinforcement Filament Yarns by Commingling Process

Carbon, aramid and glass fibers are inherently superior to conventional textile fibers in terms of mechanical properties as well as other chemical characteristics. Because of inherent advantages and disadvantages associated with each material, it is generally better to hybridize them to fully benefit of their high performance in many practical applications. In this paper, the possibility of hybridizing Carbon/Aramid-, Carbon/Glass- and Aramid/Glass- matrices has been investigated through the commingling process. In the experiment, several process parameters were selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of experiments, it was concluded that the hybridized materials has shown better performance than individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the Carbon/Glass/matrix combination turned out to be good enough for general purpose applications. However, for high tensile applications, Carbon/Aramid or Aramid/Glass with matrix combinations was better than the other material combinations. The hybridization process was also investigated under an air pressure of 5 bar, a yarn oversupply-rate of 1.5% for reinforced filaments, and 3.5% to 6% for matrix materials, respectively. It was also shown from the experimental results that Carbon/Glass/matrix combination may be desirable for small tensile force applications and Carbon/Aramid/matrix and Glass/Aramid/matrix combinations most suitable for heavy tensile force applications, respectively. As a matrix material, polypropylene and polyester have shown better performance than polyether-ether-keeton in terms of tensile property.