Applications of Low Pressure Plasma in High-tech Textiles

Abstract

The textile and clothing industries especially in developed countries are facing now-a-days some big challenges largely because of the globalization process. Therefore, the market of a high-functional, added value and technical textiles is deemed to be essential for their sustainable growth. The growing environmental and energy-saving concerns will also lead to the gradual replacement of many traditional wet chemical-based textile processing by various forms of low liquor and dry-finishing processes. The main reason for the increasing interest is that industrially well-established surface finishing processes suffer considerably from environmental demands such as large amount of water, energy and effluents. Plasma technology, when developed at a commercially viable level, has strong potential to offer in an attractive way to obtain new functionalities in textiles. The synthetic fibres such as polypropylene (PP), polyester (PES), Aramid (AR) etc. are widely used in apparel and home furnishings due to their good physical and chemical properties. The demand of these fibres increases greatly for high performance applications such as smart textiles, technical textiles, operation clothing etc. and more recently, for their potential applications in electronic textiles. But these fibres often reveal hydrophobic nature due to the lack of polar functional groups. The hydrophobic nature of such fabrics limits their application to the above mentioned areas. In addition, adhesion is fundamentally a surface property, often governed by a layer of molecular dimensions, which necessarily required for coating, bonding and printing of synthetic textiles. The low surface energy of hydrophobic polymeric materials results in intrinsically poor adhesion. On the other hand, some natural fibres (e.g. cotton, wool, linen) and synthetic fibres (e.g. rayon, viscose, acetate, spun nylon) exhibit to be hydrophilic in nature due to their polar functionalities. Hydrophilicity of such fibres may act as a barrier for their applications in many areas where liquids repellent is necessary. It is a wide-reaching technical effect that is sought after in several industry sectors, from biosciences, healthcare and electronics to industrial filtration, sports and active wear. In addition to water repellency, other liquids such as oils, inks and alcohols repellency often required. Liquids are constantly in use around us, in the majority of cases in the form of rain water and food and beverages. Arguably, the most noticeable, unfavorable interactions of these liquids are with textile products such as clothing, carpets and upholstery, so added value can be provided by protecting these items from interacting with the liquids, enabling the liquids to roll off or be dabbed away, leaving the underlying material unchanged. Furthermore, hydrophobicity of textiles is frequently associated with self-cleaning properties. When a water droplet rolls off the surface, the surface impurities such as dust get carried away by the droplet resulting in a self-cleaning effect. Using plasma technology to modify textile surfaces with precision cleaning, etching, chemical priming for lowering or raising surface energy can be used to obtain a desirable property of an end product. The plasma technology, a dry and eco-friendly technique, avoids waste water production which is a unique advantage over the wet-chemical processes. This benefit extends into all market areas, where the end product can undergo the plasma enhancement process to provide properties such as adhesion, hydrophilic, liquid-repellent etc. However, to transfer this technology from laboratory into industry, both the scale-up and economic aspects have to be regarded. Main objective of this work is to study the possibility of substituting plasma processes for the traditional wet chemical methods using an industrial plasma reactor aiming to produce wash permanent super-hydrophilic, super hydrophobic textile surfaces.