Jimmy Kwok-cheong Lam

Textile and apparel supply chain management in Hong Kong

Purpose – This paper aims to review the concept of supply chain management. The typical problems facing with textile and apparel supply chain are short product cycle for fashion articles, long production lead‐time and forecasting errors for fashion items. The Hong Kong textile and apparel supply chain faces additional problems of distance from customers in the US and European markets, long production lead‐times and minimum batch sizes for production, and, recently, elimination of quota restriction in the US market, all of which force them to improve efficiency and enhance competitiveness through supply chain management. Seeks also to provide a selective bibliography for industrial practitioners with sources which can help them develop their supply chain strategies for the fashion market in Hong Kong.Design/methodology/approach – A range of recent published (1993‐2005) works, which aim to provide practical advice are critiqued to aid the individual practitioner to manage its supply chain strategies in Hong...

Negative Poisson's Ratio Weft-knitted Fabrics

This paper presents a study of using weft-knitting technology to fabricate negative Poisson’s ratio (NPR) knitted fabrics, which exhibit the unusual property of becoming wider when stretched. Based on a geometrical analysis of a three-dimensional NPR structure constructed with parallelogram planes of the same shape and size, a new kind of NPR weft-knitted fabric was firstly designed and fabricated on a computerized flat-knitting machine. Then the NPR values of these fabrics were evaluated and compared with those from the theoretical calculations. The results show that all knitted fabrics have the NPR effect, which decreases with increased strain in the course direction. This variation trend is consistent with the theoretical prediction. The results also show that the main structure parameter affecting the NPR effect of a fabric is the opening angle at its initial state. Fabric with a smaller opening angle will have higher NPR values. This paper demonstrates the feasibility of fabricating NPR-knitted fabrics by using weft-knitting technology if a suitable structure and parameters are selected.

Structure and Properties of Low Twist Short-staple Singles Ring Spun Yarns

Low twist singles ring yarns are desirable for their low residual torque, high bulk and softness, as well as high spinning productivity. However, conventional low twist ring yarns have very low strength and, thus, cannot be used. In this paper, a modification technique is described for producing singles ring yarns with a low twist and a relatively high strength simultaneously. A false twister was used to increase fiber migration and entanglement in the spinning triangle, leading to a reinforcement of yarn strength. The yarn cross sectional structure, fiber path and yarn surface were examined and yarn tensile and torsional properties were evaluated. The results revealed that the modified yarn had a structure and properties different from the conventional ring spun yarns. The fiber path modification was kept in the resultant yarn.

The Poisson Ratio and Modulus of Elastic Knitted Fabrics

There is a significant Poisson effect for knitted fabric under tensile deformation. It is an important parameter for practical pattern design, numerical simulation of garment pressure distribution and garment dressing system. However, it is still difficult to measure the fabric Poisson ratio quickly and accurately. In this paper, a method for testing the elastic knitted fabric Poisson ratio and modulus was proposed based on orthotropic theory and strip biaxial tensile test. The fabric’s Poisson ratio and Young’s modulus are identified by linear regression, while the obtained values are validated by uniaxial tensile tests.

Influence of knitted fabric construction on the ultraviolet protection factor of greige and bleached cotton fabrics

The alarming increase of incidence of skin cancer has hastened development of ultraviolet (UV) protective clothing and research on UV protection of apparel. Although various fabric parameters that affect ultraviolet radiation (UVR) transmission were studied by researches, most of them focused on woven fabrics and chemical approach in enhancing UV protection. There were few studies concerning knitted fabrics, in particular the influence of fabric constructions on ultraviolet protection factor (UPF) and structural properties. The magnitude of transmission and scattering of UVR through a fabric is decided by fabric construction or knit structure, which is classified by geometrical arrangement of yarns and fibers of the fabric. This paper aimed at studying the influence of different knit structures upon the UPF with the three main knit stitches incorporated in the knitted fabric constructions, namely the knit, tuck and miss stitches. The UPF and structural characteristics, including thickness, weight, stitch density and porosity of greige and bleached knitted fabrics with different knit structures, are compared by adopting factorial analysis of variance. The results show that fabrics with miss stitches possess a higher UPF than fabrics with tuck stitches. The double-knitted fabrics have better UV protection than the single-knitted fabrics overall, but bleaching has different impacts on the UPF of single- and double-knitted fabrics. The study reveals that fabric thickness or weight cannot be used solely in explaining the UV protective performance of knitted fabrics. However, fabric porosity can be a good indicator for UV protection when comparing fabrics with similar fabric weight and thickness but different structures or fiber contents.

Multivariate studies of mechanical properties for wool and cotton fabrics

In this study, the mechanical properties of fifty-eight light-weight wool/wool-blend fabrics and twenty medium to heavy-weight cotton denim fabrics were analyzed by multi-dimensional techniques of principal component analysis. The technique reduced the dataset of wool/wool-blend fabrics into seven components and explained 86% of the population variance. For the cotton denim fabrics, the dataset was reduced into five components and explained 95% of the population variance. Fabric surface properties and fabric bending and shear properties were the most important properties to explain the fabric stiffness hardness and tailorability for these two fabric classes. The results show how multivariate statistical analysis techniques of fabric mechanical and surface property data for two very different groups of fabrics can provide a basis for the specification and control of fabric quality along the textile and apparel supply chain. These reduced datasets with the most important component extracted first and the least important component extracted last, allow the supply chain members to focus directly on the key factors for product design and development.

Effect of Alkaline and Neutral Protease Enzyme Pretreatment Followed by Finishing Treatments on Performance Properties of Wool/Cotton Union Fabric: A Comparative Study

Literature information on the application of protease enzyme pretreatment followed by finishing treatment on wool-blended textiles for improving their performance properties is still inadequate. Wool/cotton union fabric was pretreated with savinase and papain enzymes separately followed by finishing with nine different finishing combinations. Savinase pretreatment had an influencing effect on handle and smoothness properties while papain pretreatment had improved comfort and mechanical properties. Each finishing formulation gave specific performance property in addition to softness. It is concluded that savinase pretreatment followed by Sandosoft-SPG+Ceraperm-MW+Ceraperm-Aqua combination finishing could be used to impart both softening and comfort finish to the wool/cotton union fabric.

Impacts of yarn twist and staple length on UV protection of plain-knitted cotton fabrics

Yarn construction is an important attribute in knitting and end use performance of knitwear. Holistically, yarn construction affects fabric thickness and weight, and thereby influences ultraviolet (UV) protection of fabrics. Although impact of yarn construction on UV protection of fabrics is apparent, there appears to be limited research on it. This paper studied the UV protection of plain-knitted fabrics made of three types of ring-spun cotton yarns varying in yarn twist level and staple length. The results show that these yarn properties affect UV protection of fabrics differently before and after laundering. The modified low-twisted yarn possesses a bulky feature which creates a porous fabric structure for more ultraviolet radiation (UVR) transmission. The extra-long staple yarn offers uniform fabric appearance for higher UVR reflection. However, the regularity of yarn also restricts the fabric shrinkage in laundering and thus improvement in UV protection by shrinkage is not as obvious as that provided by the conventional short-staple yarn.

In Vitro assessment of ultraviolet protection of coloured cotton knitted fabrics with different structures under stretched and wet conditions

Clothing provides intrinsic ultraviolet (UV) protection that can be improved by colouration. However, the daily wearing condition can undermine the UV protection of coloured clothing wherein garments are stretched by body movement and/or wetted by perspiration of wearers. Knitwear is an indispensable clothing in summer, but its UV protection against wearing conditions lacks extensive study especially in a fabric structural approach. This article aimed at narrowing the research gap by focusing on the UV protection against stretch and wetness provided by various knitted fabric constructions incorporating the knit, tuck and miss stitches. The results show that the black knitted fabrics exhibit a significant reduction in the UV protection factor by 53% on average at a 10% stretch level. Knitted fabrics with miss stitches retained good UV protection even when the fabrics were stretched by 20% of its original dimensions.

A study on ultraviolet protection properties of 100% cotton knit fabric: effect of fabric structure

In this paper, the effect of different structures of knit fabric on ultraviolet (UV) protection was studied. Different knit structures were investigated, which included single knits such as plain, pineapple, lacoste and other combinations of different knitting stitches of knit, tuck and miss as well as double-knit structure of half milano, full milano, half cardigan, full cardigan, 1 × 1 rib and interlock. The results showed that double-knit fabrics provide better UV protection than single-knit fabrics.