October 23, 2007
Protective Clothing-From Nomex to Nanofibres for DuPont
By Wilson, Adrian
Brands such as Kevlar, Nomex and Tyvek have historically linked the DuPont name with protective clothing required across a range of industries. Today the company continues to develop products in response to market needs, reports Adrian Wilson. Nomex, DuPont's heat-resistant fibre which is employed in a wide range of protective apparel, is 40 years old this year. It was introduced in both nonwoven and woven forms in 1967 after scientist Wilfred Sweeny found a way to make a meta-aramid with high molecular weight that could be spun into a tough crystallizable fibre with outstanding thermal and flame-resistant properties.
Nomex fibre is perhaps best known as a critical component in protective apparel and today more than three million firefighters around the world are protected by turnout gear, stationwear and accessories made of it. The fibre is also used in apparel worn by military pilots and combat vehicle crews, racing drivers, pit crew members and track officials, and industrial workers at risk from flash fire and electric arc hazards;for instance, US troops in Iraq are being outfitted with Nomex apparel to protect them from burns caused by roadside bombs.
DuPont last year announced a $100 million global expansion plan to increase worldwide capacity for Nomex. The company plans to build a new facility in Asturias, Spain, to produce isophthaloyl chloride, one of the main ingredients for Nomex, and will also add equipment to its existing Asturias manufacturing site that will increase Nomex capacity by more than 30%. These investments will support new uses including:
* Nomex Limitedwear for Military-a lightweight, limiteduse garment designed as specified by the military to help protect soldiers from flash fires;
* Selective Permeable Membrane (SPM) Technology. DuPont is working with the US Army Soldier System Center in Natick, Massachusetts, on lightweight suits featuring SPM technology, which will help protect users from chemical and biological agents; and
* DuPont Tychem ThermoPro - A single garment that combines flash fire and chemical protection.
TYVEK SHARES THE ANNIVERSARY
Another DuPont product, Tyvek, also marks its 40th anniversary in 2007. Combining certain characteristics of paper, film and fabric, Tyvek is lightweight but still strong, and breathable while also resistant to water, a wide range of hazardous materials, chemical degradation and tearing.
It is employed in disposable protective garments that are widely used in manufacturing, laboratory and emergency response settings, providing protection from hazardous materials.
Recent product introductions have included Tyvek Comfort fit design coveralls, which were designed based on wearer input and provide workers with a significantly more comfortable fit, improved mobility and enhanced durability.
The initial discovery of Tyvek was made in 1967 when a DuPont researcher recognized the potential value of a high strength white polyethylene fibre formed in samples taken from a new high-density polyethylene process. A programme was established to develop the material into an engineered nonwoven sheet structure, which today is produced at DuPont's plants in Richmond, Virginia and in Luxembourg.
President of DuPont Hybrid Membrane Venture is Sandra S. Van Warmer. She says that the company has succeeded in electrospinning nanofibres on a commercial basis.
US troops in Iraq are being outfitted with Nomex apparel to protect them from burns caused by roadside bombs.
DuPont's fibre innovation continues today and it is currently promoting its new Hybrid Membrane Technology (HMT).
"HMT is a nanofibre-based technology that bridges the gap between nonwoven substrates and membranes" explainedVicepresident and General Manager of DuPont Nonwovens Matthew L. Trerotola.
HMT's development involved two DuPont businesses: Nonwovens and Advanced Fiber Systems, which is responsible for Nomex and the para- aramid (Kevlar) performance fibres. Ground was broken at a new manufacturing plant in Korea in 2005 and production started up in May 2006, with commercialization of products beginning immediately afterwards.
"The electrospinning method of producing nanofibres has been around since the 1930s but the unique breakthrough made by DuPont was in developing production on a commercial basis and that's what we have done in Korea," said President of DuPont's Hybrid Membrane Venture Sandra S. Van Wormer. Product consistency is very important, she added.
At the moment HMT products are made of polyamide but the technology is being developed for a range of polymers and fibres. Initially targeted at the filtration market, it is likely to find many future applications in protective clothing, especially in combination with Nomex, Tyvek and DuPont's other famous brands in this field.
Sandra VanWormer, President, DuPont Hybrid Membrane Venture.
E-mail: [email protected]; http:// www.dupont.com
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