Danmei Sun

Effect of low temperature plasma treatment on the scouring and dyeing of natural fabrics

The contact angles, wicking properties, scourability, and dyeability of wool and cotton fabrics are affected by low-temperature plasma treatments. After treatment, wool and cotton fabric specimens show increased hydrophilicity and improved scouring and dyeing processing by nearly 50%.

Investigating the Plasma Modification of Natural Fiber Fabrics-The Effect on Fabric Surface and Mechanical Properties

Following previous work [Textile Research Journal, 74,751-756 (2004)], the mechanical and surface properties and handle of wool and cotton fabrics were measured using the KES-FB system after different stages of treatment. This investigation shows that the mechanical properties of wool and cotton changed remarkably after oxygen plasma treatment. There were no significantly observed differences between plasma treated and untreated fabrics after wet scouring and dyeing.

Plasma modification of Kevlar fabrics for ballistic applications

The currently used high-performance fiber materials for soft body armor have very low surface friction and this has become an issue in the effectiveness of ballistic energy absorption. In this study, non-polymerizing reactive plasma gas N2 and chemical vapor (CH3)2Cl2Si were employed to modify Kevlar fabric surface for the application of ballistic impact material. Scanning electron microscopy observations yield information about the surface effect of the fabrics after plasma treatment. The surface morphology of the treated fabrics was studied. Energy-dispersive X-ray analysis was used to analyze the surface chemical properties of the treated samples. The yarn pulling-out test shows that the resistance to pulling out yarns from fabrics plasma-treated treated with N2 and (CH3)2Cl2Si plasma-treated fabric is increased 18% and 300% respectively, compared with the untreated Kevlar fabric. Finite element simulation results revealed that fabric with a higher surface coefficient of friction performs better in ballistic energy absorption.

Engineering and analysis of gripping fabrics for improved ballistic performance

Previous studies show that fabric construction is one of the key factors affecting the performance of ballistic fabrics. In order to investigate the effect of yarn gripping in fabrics, plain woven narrow fabrics with different widths have been designed and studied. In terms of narrow fabrics, it was found that narrower fabric demonstrates better performance than wider ones under low impact energy due to the better weft yarn gripping effect of the selvages. In the case of higher impact energy, wider narrow fabric shows better ballistic performance in having sufficient material to dissipate the impact energy. Different ballistic panels were made for ballistic testing, with each panel only formed from the same fabric. Performance of narrow fabric panels is disappointing compared to the broad fabric panel due to the discontinuity of the fabric material. A novel broad fabric has been engineered providing both enhanced yarn gripping and material continuity. Tests showed that panels made from such fabrics have improved performance against both back face deformation and projectile penetration.

Computational analysis of effective thermal conductivity of microencapsulated phase change material coated composite fabrics

Microencapsulated phase change materials have been widely used as filler material to develop thermoregulating textile composites. Phase change material has unique property of latent heat that can absorb and release energy over constant temperature range. In this work a method is developed to predict the effective thermal conductivity of microencapsulated phase change material coated composite woven fabrics via finite element analysis. For this purpose unit cell of microencapsulated phase change materials as coated material and woven fabrics were developed and analysed by applying different boundary conditions. Validation of the models was carried out on the basis of strong correlation in effective thermal conductivity values of the microencapsulated phase change materials coated composite fabrics between experimental results and the predicted results from post-processing calculation by finite element method.

Investigating ballistic impact on fabric targets with gripping yarns

The purpose of the research is to investigate the fabric structure (with gripping yarns) in influencing ballistic performance aiming to improve the ballistic performance of the currently used body armour materials. Thirteen different fabrics having gripping yarn were designed along fabric warp and/or weft directions. Their ballistic performance in terms of energy absorption has been studied and comparisons made among the single layered fabrics and between the two double layered fabrics, as well as to the conventional used a plain woven fabric for both cases. It was found that fabrics with gripping yarns have improved fabric ballistic performance. The inter-jointed two-layer fabric performed better than the un-jointed two-layer fabric, and it showed a 16.6 % increase in the energy absorption. The implication of the research is that body armour can be made lighter without reducing ballistic impact performance by using gripping yarns.

Investigation of the effect of continuous finishing on the mechanical properties and the handle of wool fabrics

The effect of scouring, bleaching and dyeing on the low stress mechanical and surface properties of wool woven fabrics was studied. Fabric properties were measured by the KES-FB system. In general, mechanical properties of the treated fabrics are greatly affected by scouring, moderately by dyeing and least by bleaching.

Automated model generation of knitted fabric for thermal conductivity prediction using finite element analysis and its applications in composites

Thermal property of clothing has significant impact on thermal comfort of the wearers. In an extreme working condition body releases a lot of heat and sweat, in order to keep the body dry and at normal temperature these heat and sweat should be released in the environment. The thermal comfort of the fabrics mainly depends on how well it transmits heat and moisture to the environment. In this work finite element models have been developed to predict the thermal conductivity of plain weft knitted fabrics. Fabrics with different stitch density and yarn count were used in this work. A unit cell model of the fabrics was developed by using the actual geometrical parameters. Material orientation of the yarn was used for assigning the thermal conductivity of each element in the yarn. Boundary conditions were applied on unit cell of the fabrics for the determination of thermal conductivity. The geometrical models of the fabrics were generated by a plug-in which was developed in Abaqus/computer aided engineering using Python script. It has been found that thermal conductivity between the predicted results obtained from finite element analysis and experimental results from an in-house developed device is highly correlated. Furthermore, the application of geometrical model in different areas has been discussed, and technique is developed for the prediction of effective thermal conductivity of plain weft knitted composite fabric.

Development of Thermal Stable Multifilament Yarn Containing Micro-encapsulated Phase Change Materials

Phase change materials are used for the development of thermo-regulating textiles to give thermal equilibrium to the accustomed textiles for changing climates. Phase change materials having their melting point near the skin temperature are found to be useful for textiles in which n-octadecane is widely used. This paper reports the development of multifilament polypropylene yarn containing Microencapsulated Phase Change Materials (MPCM) developed and manufactured by a new designed spinneret die with 7 holes. SEM and DSC have been used to examine the morphology and the latent heat of multifilament Polypropylene yarn containing up to 8 % of MPCM. The effect of processing parameters on mechanical properties of yarn with respect to amount of MPCM has been discussed.

Cotton fabric mechanical properties affected by post-finishing processes

Following the work done previously [1]. In this paper, the effect of various post-finishing agents on the low stress mechanical and surface properties of dyed cotton fabrics, as well as their handle value have been studied. The mechanical properties of the treated cotton fabrics were measured by the famous KES-FB system. It has been found that cotton fabric mechanical properties and fabric handle can be modified by not only the external finishing agents but also the internal finishing agents which are used for correcting the inherent defect of the fabrics. The results in this report will inform the textile industry in engineering required fabric properties with appropriate finishing processes.