02/16/2011

www.gupta-verlag.de/polyurethanes

Synthetic fibres with PolyTHF stay flexible even in the cold

"A synthetic fibre with truly exceptional properties is needed if the clothing is to withstand not only the cold, but also the athlete's vigorous movements and perspiration," says Dr. Dieter Rodewald, Senior Manager Technical Services, BASF Intermediates in Asia. "Spandex fibres, made from the BASF intermediate PolyTHF, are ideally suited to these extreme conditions. The textiles are permeable to water vapour and retain their elasticity and flexibility even at icy temperatures, making the fabric feel like a second skin." Well into the 20th century, this was something people could only dream of. As they ventured out into the snow wearing a woolen jumper, velvet pants or fur jacket, they would feel their fingers - and their clothes - gradually getting cold. The natural fibres became rigid and the pants felt as stiff as a board. The advent of synthetic fibres in the nineteen-thirties put an end to this unhappy situation.Spandex fibres are unfazed by frost or humidity. A look at the labels on different items of clothing will tell you that most textiles contain some spandex: you'll find it in socks, in long underpants and leggings, sweaters, T-shirts and jacket linings. In fabrics, spandex fibres always come mixed with other fibres, for example wrinkle-free and tear-resistant polyamide. Functional underwear such as ski underpants or jerseys contains 5 - 10 % spandex fibres. The spandex content in stretch jeans is about 3 %."Spandex fibres come in a variety of grades, for example customised for swimwear or high-quality outerwear applications," explains Prof. Thomas Gries, Director of the Institute of Textile Technology at RWTH Aachen University. The more stretch a fabric is to have, the more PolyTHF the spandex fibre should contain. "The spandex content in functional wear, swimwear, jerseys and underwear is higher than in upmarket outerwear," says Gries. A low spandex content is sufficient to accommodate the normal range of everyday movements in trousers or shirts.Athletes especially benefit from the superior elasticity of a spandex fibre, which consists of about 80 % PolyTHF. With this percentage, even doing the splits would be no challenge for the pants. "Garments made of fabric containing spandex retain their fit even during extreme body movements," explains Gries. "Spandex fibres will stretch to as much as seven times their original length." Another advantage of these fibres is their long-term dimensional stability, which means they retain their extreme elasticity and always return to their original shape after stretching. Even when it's cold outside. Coping with skiers' perspiration is a job that demands a fibre immune to humidity. Step forward PolyTHF: "These fibres are the perfect solution for direct body contact applications, in sportswear or underwear for example," explains Dieter Rodewald. Moreover, the arrangement of atoms in PolyTHF molecules make them hard to digest for microorganisms. That's why microbes and mites shun spandex fibres - good news for allergy sufferers.About 70 % of the PolyTHF produced by BASF goes to the textile industry. It is also used to make highly abrasion-resistant hoses and films. Cable sheathing and dashboard films are major PolyTHF applications in the automotive industry. Another important usage for this versatile material is in rail track construction. The durably elastic molecular structure makes PolyTHF-based plastics ideal for producing heavy-duty railroad bedding mats that dampen shock and vibrations. The benefits: less wear and tear, and less noise from passing trains. As a major constituent of polyurethane elastomers, PolyTHF is also used to manufacture long life wheels for skateboards and inline skates.

www.gupta-verlag.de/polyurethanes