Wool in technical textiles

Abstract

Wool was being used in clothing as early as the stone age, probably the first animal fiber to be spin and made into cloth. Due to unique properties of wool it’s called as “Natures Miracle”. Wool is being used by the apparel industry for last many years & now a day’s its increasingly being used in technical applications. To utilize wool in technical textiles requires application such that it can exploit the natural attributes of wool and control over cost. Because of the use of wool fibre into new high value technical market & developing innovative products, global demand for wool products is increasing. This paper focuses on different attributes of wool fibre for new future applications in technical textiles.

Key words: Technical textile,wool fibre, sportwool, Wool in medical application etc.

1. Introduction

Wool is the most complex and versatile of all textile fibres. It can be used to make products as diverse as cloth for billiard tables to the finest woven and knitted fabrics. The insulating and moisture absorbing properties of the fibre make fine wool products extremely comfortable to wear. The chemical composition of wool enables it to be easily dyed to shades ranging from pastels to full, rich colours. So it is called wool: “Natures Wonder Fibre”

During the last century, considerable resources have been invested in development of synthetic fibers with the same favorable qualities as wool. But so far no one has succeeded in copying nature’s own material. Due to very special and unique properties of its being widely used for conventional applications such as carpets, rugs, shawls suitings, knitwear’s, etc.The insulating and moisture absorbing properties of the fibre make wool products extremely comfortable to wearer.[1]. The chemical composition of wool enables it to be easily dyed to shades ranging from pastels to full, rich colours [2].

More recently, wool has been subjected to intense scientific study, and this has resulted in many improvements to the fibre properties like quick- dry, easy-care, and makes it a unique component in sports clothing. Wool garments can be made quick-dry. A partnership between Australian wool Innovation Ltd (AWI) and CSIRO has achieved this with its Quick Dry Merino technology. An example of it is SPORTWOOL^TM [3]

Wool fibers contain proteins whose chemical structure gives the wool its characteristic elasticity, strength and airiness.

2. Wool in Furnishing, Upholstery and Industrial uses

Performance of wool in terms of its resiliency and thermal are applied in furnishings, upholstery and industrial uses

Furnishing

Major use of wool is in carpets and custom rugs, often for special-order or one-of-a-kind rugs. Complex designs and contemporary hand woven or hooked rugs. Wool carpets are expensive than others as the pattern, texture, color, and appearance are good. [4]

Upholstery

Both wool and wool blend fabrics are used in upholstery due to its good retention appearance, excellent durability, natural flame resistance and aesthetic characteristics. For residential wool items, no additional flame retardant finish applied. While commercial wool upholstery fabric may undergo flame retardant treatment [4].

Industrial Uses

Wool is important in making felts, which help to decrease noise or for variety uses. Wool is also used to clean up oil spills. Another application is the wool mulch mats for landscape and horticultural weed control [4].

Wool in Geotextiles

As many of us know, wool as a natural fibre is bio-degradable and in fact can be an excellent fertiliser or soil conditioner. The Shoddy Wool (ground up waste wool) has long been recognized as a wonderful slow release source on Nitrogen by farmers and gardeners alike. In the 1950’s the Brussels sprouts field of Bedfordshire in England was cheered up by the different coloured wools making up the shoddy which were put on the sprout land. The famous rhubarb triangle of Yorkshire has always valued wool as a major component of organic mulch for growers of “forced Rhubarb”. Currently in New Zealand AgResearch’s Textile Team is looking into converting Wool carpet into a slow release fertilizer returning natural materials to the soil. The project involved grinding up wool carpet and mixing the shredded product into the soil to grow grass. The result of this “Grass to Grass” recycling was quite staggering- the soil containing the crushed wool carpet saw a 60% increase in dry matter production compared to the standard soil tested. The biggest growth rate was over a dry summer, where the wool carpet fertilizer worked to retain moisture in the soil.

3. Wool in Medical and cosmetic applications

Wool is the miracle fibre and also recognized for its ability to insulate and to absorb moisture almost one – third of its own weight without feeling wet. Wool fiber is also known for providing the warmth [5]. Wool can be recommended to use in medical because of following advantages:

• An excellent insulator
• Resilient fiber to reduce pressure
• Reduces friction or shear
• Wicks moisture
• Absorbs and dissipates body moisture without feeling wet
• Creates a comfortable even body temperature
• Fire resistant

Wool fiber has limited areas of application in the field of medical textile despite of it, this wonder fiber can be used in medical textile taking the advantage of its insulation property pressure relieving device can protect the skin from the effect of pressure, friction and moisture. Wool fiber provides excellent protection when placed under the back, calves and heels. This fiber has following application areas in medical [6]:

• Wool wax
• Bedsore and Pressure Sore prevention
• Medical Sheepskin Foot wears
• Foot care
• Wool Pillows

Wool wax is a naturally occurring substance, designed by nature to soften both skin and wool fibres, and to protect them against adverse outside weather conditions. The best known uses of refined wool wax products (lanolin and lanolin derivatives) are in the field of medicine, cosmetics and toiletries, which all take advantage of these natural protective qualities [7].

Wool is a relative latecomer to this process while nonwovens from man-made fibres such as polyester, polypropylene and viscose rayon, as well as blends containing cotton, wood pulp and other fibres for applications for long time[8].The AgResearch Biomaterial and Fibre & Textile both team has worked collaboratively to modify fibre and introduce new functionalities in to the fibre /textile appropriately for the development of a wide range of products for various applications. They worked on wool fiber & examples of recent new product developments are self cleaning WWB garment (nanotech approach), functional wool fabric/textile, antimicrobial wool fibre /fabrics, Nano fibre bio mat scaffold, Reconstitute bio fibre, Anti microbial bio fibre etc. these modified fibers can be used in medical[9].

Only super fine wool can be used in medical textiles and the special wool fibers like angora which provides warmth (approximately seven times than wool) can be used in medical textiles. Presently wool based medical textiles are very limited but the consumption of wool fiber in medical can be explored and will open the new areas for research and development. The possible areas of wool will be in surgical hosiery, super absorbent layer, blankets; sheets etc. Also wool can be very well used in blends with other synthetic fiber in surgical gowns and surgical drapes etc. hence the use of wool can be in health care and in the hygiene products [6].

4. Wool in Sportech

It is special clothing and sports equipment to enhance protection, comfort and performance. Protection against over-warm­ing or cooling, owing to high water vapour permeability i.e. carrying off perspiration, good warmth retention and adequate air permeability. The user’s feeling is also positively af­fected by soft handle and good shape [10] Wool has good, natural wicking property and also it will provide insulation even in wet condition, but it is slow to dry. It is a popular misconception that synthetic fabrics dry more quickly than their natural counterparts. In fact the rate of evaporation from fabrics depends on the surrounding climate conditions and structure of the fabric. A wool fabric has been shown to absorb significantly more sweat than a polyester fabric (of comparable structure) followed by rest during a period of exercise. The amount of moisture desorbed from the wool fabric was significantly higher than the polyester fabric, and the skin temperature decreased faster and recovered more slowly after contact with the wool fabric compared with polyester fabric.The removal of the sweat in vapour form from the micro-climate between the skin and fabric reduces the retention of liquid sweat, leaving drier and more comfortable. Wool fibre has a unique natural thermal regulation and vaporous management properties which helps in cooling down and controls body temperature [11].

Development of the new technologies and process like chlorination of the wool fibre makes it wearable next to skin and use as a base layer in sports textile garment. Wool Research Association, Thane has developed itch free woolen products by plasma treatment on wool fibre surface, in this process of plasma treatment the lipids gets removed from the fibre surface, which makes wool surface quite hydrophilic. The plasma treated woolen gives good wicking property. These new developments make the wool fibre suitable for sportswear. Also international organizations like Australian Merino Wool Industry (AWI) and Australian Commonwealth Scientific and Research Organization (CSIRO) are putting lots of efforts for incorporating merino wool into sports textiles and exporing new technical applications of wool fibre [12, 13]. The excellent moisture wicking and comfort properties make the wool fiber suitable for the sportswear .

5. Sportwool™

Sportwool™ is a unique fabric engineered by CSIRO for use in active sportswear that is more comfortable before, during and after vigorous physical exercise, allowing athletes and sports people to achieve peak performance. Sportwool™ is a lightweight, composite fabric consisting of a layer of machine-washable superfine Merino wool next to the skin and a layer of tough, easy-care polyester on the outside. The complete separation of the two component fibres on each face of the fabric ensures that a continuous layer of wool is in contact with the skin, producing an exceptional moisture management system that a 100 per cent synthetic product cannot match.

Sportwool™ manages the effects of sweating in two ways.

A few minutes after vigorous exercise starts, athletes begin to sweat. At this point the skin is dry but humidity near the skin begins to build rapidly. Because wool absorbs moisture, the inner wool layer of Sportwool™ absorbs water vapour (Fig. 1), slowing the rise in humidity, and also delaying the appearance of liquid sweat [14].

Then, as liquid sweat forms on the skin, the soft, comfortable inner wool layer ‘pumps’ it to the outer synthetic fibre layer, where it spreads out and evaporates, creating a cooling effect [15].

6. Wool in protective clothing

It has been subjectively and scientifically proven from a number of perspectives that wool has the advantage over other fibre types. Irrespective of whether wool is used for protection or comfort, its applications are suitable for conditions ranging from the hot and humid tropics to the harsh and freezing Antarctic [16].

Protective clothing against heat and flames should be evaluated not only for flame-resistance but also for protection against various heat exposures from convection, radiation, and conduction sources, depending on the end-use, to ensure a realistic assessment of the potential protection offered and required. Zirpro wool of adequate construction for the end-use required gives best protections in the various heat-exposure tests [17]. The protective power of typical aramid-based multi-layered ballistic fabrics designed to defeat high-velocity ballistic impacts, can be improved if wool is incorporated into the weave structure. Although the synthetic is still the primary energy-absorbent material, the wool plays a complementary role by increasing resistive interactions between the yarns and filaments. Wool restricts the lateral separation of the synthetic yarns and ensures that more directly impacted yarns are held in place to dissipate the impact energy. Wool increases the energy-absorption mechanism of yarn pull-in by increasing the longitudinal friction along the yarns/filaments, in particular near the free edges of the fabric layers. The wool absorbs water that may otherwise lubricate synthetic filaments and so improves the wet performance. Ballistics tests have shown that synthetic fabrics blended with wool can at least match the dry or wet ballistic performance of an equivalent pure Kevlar fabric when tested under National Institute of Justice (NIJ) Ballistic Standard Level III A. The inclusion of the wool can significantly improve the tear strength of pure synthetic ballistic fabrics [18].

Conclusion

Contrary to common belief, wool is an extremely technical fibre and its presence in technical textiles cannot be neglected. Further its range of applications can be widen by means of chemical modification of the wool fibre or blending with suitable fibres for specific technical applications, its uses in technical textiles can be explored .

References

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