The evolution of fibre developments has gone through the phases of conventional fibres, highly functional fibres and high-performance fibres. Polyester is the single most common fibre used for sportswear and active wear. Other fibres suitable for active wear are polyamide, polypropylene, acrylics and elastanes. Wool and cotton fibres are still finding applications in leisurewear. Synthetic fibres can either be modified during manufacture, e.g. by producing hollow fibres and fibres with irregular cross-section, or be optimally blended with natural fibres to improve their thermo-physiological and sensory properties. Synthetic fibres with improved UV resistance and having anti-microbial properties are also commercially available for use in sportswear.
Improved fibre spinning techniques in melt spinning, wet spinning, dry spinning as well as new techniques such as gel spinning, bi-component spinning and microfibre spinning, have all made it possible to produce fibres, yarns and fabrics with unique performance characteristics suitable for use in sportswear and sports goods. New technologies for producing microfibres have also contributed towards production of high-tech sportswear.
By using the conjugate spinning technique, many different types of sophisticated fibres with various functions have been commercially produced which has resulted in fabrics having improved mechanical, physical, chemical and biological functions. The technique of producing sheath/core melt spun conjugate fibres has been commercially exploited for producing added-value fibres. Unitika produced the first heat-degenerating conjugate fibre with a core containing zirconium carbide (ZrC). Since ZrC absorbs sunlight (visible and near-infrared radiation) and emits far-infrared radiation, one feels warmer when one puts on a jacket made from such fibres. Other types of heat-generating fibres contain ceramic micro-particles.
Today, a wide range of high-performance fibres is commercially available for technical and industrial applications. These types of fibres are used in sports protective wear/equipment developed for impact protection and in textile reinforcement in sports products for different applications. Among the speciality fibres already established are the following:
± p-aramid fibre to provide high strength and ballistics
± m-aramid fibre to provide flame and heat resistance.
Ultra-high tenacity polyethylene fibres (UHMWPE).
Gel spun, ultra-high molecular weight polyethylene fibres with extremely high specific strength and modulus, high chemical resistance and high abrasion resistance.
Polyphenylene sulphide fibres (PPS).
Crystalline thermoplastic fibre with mechanical properties similar to regular polyester fibre. Excellent heat and chemical resistance.
Polyetheretherketone fibres (PEEK).
Crystalline thermoplastic fibre with high resistance to heat and to a wide range of chemicals.
· Novoloid (cured phenol-aldehyde) fibres.
High flame resistance, non-melting with high resistance to acid, solvents, steam, chemicals and fuels. Good moisture regain and soft hand.
· PBO (p-phenylene-2,6-benzobisoxazole) fibres.
The strength and modulus of this fibre exceed those of any known fibres.
Highly functional fabrics
There has been a strong growth in the development and use of highly functional materials in sportswear and outdoor leisure clothing. The performance requirements of many such products demand the balance of widely different properties of drape, thermal insulation, barrier to liquids, antistatic, stretch, physiological comfort, etc. The research in this field over the past decade has led to the commercial development of a variety of new products for highly functional end-uses. By designing new processes for fabric preparation and finishing, and as a result of advances in technologies for the production and application of suitable polymeric membranes and surface finishes, it is now possible to combine the consumer requirements of aesthetics, design and function in sportswear for different end-use applications. The fabrics for active wear and sportswear are also specially constructed both in terms of the geometry, packing density and structure of the constituent fibres in yarns and in terms of the construction of the fabric in order to achieve the necessary dissipation of heat and moisture at high metabolic rates. Many smart double-knitted or double- woven fabrics have been developed for sportswear in such a way that their inner face, close to human skin, has optimal moisture wicking and sensory properties whereas the outer face of the fabric has optimal moisture dissipation behaviour.
In addition to the innovations in highly functional man-made fibre-based fabrics, advances have also been made in cotton and wool fabrics for sportswear. An example is the development of `Sportwool’ weatherproof technology, where the constituent fibre, yarn and fabric properties and the fabric finishes of `Sportwool’ are supposed to create a drier and cooler microclimate.
Since the introduction of Gore-Tex fabric in 1976, a variety of lightweight breathable highly functional fabrics have been developed worldwide. Highly functional fabrics are generally characterized as being waterproof/moisture permeable, sweat-absorbing and with high thermal insulation at low thickness values. These fabrics are now extensively used in making sportswear and sports shoes. One can say that these products are basically complex materials with diverse functions. In many of these products the requirements of comfort and fashion have successfully been integrated with segmentation in uses.
Important developments are envisaged in making multifunctional coated or laminated fabrics for different applications. For example, some new innovative functional textiles for protective clothing were recently introduced by W. Gore and Associates. Gore-Tex Airlock is a functional textile which was developed by Gore for the special needs of firefighters. The concept of this product is to eliminate the conventional, bulky, thermal insulation layer and substitute it by a protective air cushion. Dots consisting of foamed silicone are discontinuously applied to a fibre substrate and anchored within the microporous Gore-Tex membrane. They measure only a few millimetres in height, creating a defined air cushion between the adjacent flame-retardant face fabric and the inner lining. This laminated fabric is characterized by thermal insulation, breathability, perspiration transport, absorption and quick-dry properties.
Biomimetics and textiles
The structure and functions of natural biological materials are precise and well defined. The imitation of living systems, `biomimetics’, could make it possible in future to replicate the molecular design and morphology of natural biological materials since their structure and functions are related. Already in many laboratories around the world, R&D work is going on in the field of biomimetic chemistry and fabric formation. A typical example is the development of water- and soil-repellent fabrics produced by imitating the surface structure of a lotus leaf. Water rolls like mercury from the lotus leaf, whose surface is micro-
scopically rough and covered with a wax-like substance with low surface tension. When water is dropped on to the surface of a lotus leaf, air is trapped in the dents and forms a boundary with water.
There have been some interesting developments taking place regarding intelligent textiles and interactive materials with great market potential in the sportswear sector. These materials readily interact with human/environmental conditions thereby creating changes in the material properties. For example, the phase-change materials and shape-memory polymers embedded in fabric layers will be able to interact with a human body and produce thermoregulatory control by affecting the microclimate between the clothing and the human skin. In addition to the two dimensions of functionality and aesthetics, if `intelligence’ can be embedded or integrated into clothing as a third dimension, it would lead to the realization of protective and safety clothing as a personalized wearable information infrastructure.
Reference: “Textiles in sports” by R.Shishoo