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Graphic element Research > Growth > Research projects > Materials & technologies projects > Smart fibres protect their users - and their makers
Graphic element Smart fibres protect their users - and their makers
    07-03-2002
 

Textiles that change colour in response to light or heat have appeared as fashion gimmicks - but the effects are typically diminished in a relatively short time by repeated wearing and washing. In the BRITE-EURAM SMARTEX project, techniques for grafting special functional groups onto polymer fibre molecules were used to produce similar characteristics, with improved durability and more practical applications.

While Europe's textiles industry has difficulties in competing with the bulk commodity output of lower-wage economies in the Middle and Far East, one of its strength lies in the ability to manufacture more demanding high-tech products. The SMARTEX consortium, led by the Institut Français du Textile et de l'Habillement (IFTH), has capitalised on this by developing advanced polymer fibres with photochromic, thermochromic and other properties that cause changes in response to light, heat, pressure or other stimuli.

Bringing added value
 

These 'smart' materials are intended to perform specific technical functions, rather than simply satisfying a transient fashion demand. They thus offer valuable opportunities for both the fibre suppliers and their customers to gain market share with products of high added value.

Italian partner Nylstar essentially sought a means of detecting counterfeiting of its fibres - while Dogi , from Spain, intended to produce counterfeit-proof sports clothing and photochromic swimsuits with the ability to afford protection against harmful UV radiation from the sun. Another Spanish participant, Murtra , initially focused on the potential of piezochromic and photochromic effects for monitoring stress and ageing of load-carrying slings and ropes, but subsequently also developed an interest in supplying fibre for protective apparel applications.

 
New methods explored
 

Previous methods of obtaining functionalised polymers - such as solution coating or dye dispersion - suffered drawbacks because of a tendency for the polar additives to desorb from the non-polar matrices. The project team therefore explored methods of chemically grafting functional groups permanently onto the polymer molecules.

Laboratory experiments were conducted using untreated and specially treated polypropylene provided by Murtra, plus polyamide 6 and 66 from Nylstar, as the base polymers. These were tested with an extremely wide range of functional molecules stemming principally from collaboration between the University of Ghent and AIMCO France.

The challenge was to identify candidates that would confer the desired properties, while also being suitable for grafting and capable of resisting degradation during the high-temperature fibre extrusion spinning.

 
Success in several areas
 

To date, the most promising results have been obtained with photochromic polypropylene yarns. These can now be made in a range of colours using conventional production technology - and have been shown to exhibit a large improvement in UV protection compared with that of virgin fibre. Samples of the finished textiles were demonstrated at a wind-up meeting for the project in September 2001.

Trials with polyamide have as yet proved less fruitful. This is due to breakdown of the grafted components caused by acidity during the extrusion process, plus a reduction of the UV blocking effect in the presence of the commonly used titanium dioxide filler.

Success was achieved in counterfeit protection by incorporating a visually undetectable 'signature' that can be activated on exposure to a suitable excitation source, such as UV or X-ray radiation. For obvious reasons, the details of this remain a closely guarded secret - but it is envisaged that regular changing of the marker function will enable legitimate manufacturers to stay ahead in the battle against forgeries.

Work on the piezochromic detection of rupture risk in over-stressed slings and ropes was abandoned after about two years. However, an alternative piezoelectric mechanism appears to offer possibilities; this could probably be brought to marketable status with another two or three years of research.

Meanwhile, several patents have been granted or are being applied for on the processes and the products so far realised.

 
Broader co-operation
 

"Our industrial partners have been particularly satisfied with the outcomes of this project," remarks co-ordinator Laurence Caramaro of the IFTH. "The good relations developed during the three-year term have also encouraged them to enter into broader areas of collaboration.

"In addition, we took the opportunity of a technical meeting to organise a networking conference, to which we invited members of the consortia of other projects in which IFTH was involved," she adds. "This has led to still more fruitful exchanges. In particular, the presentation of our work resulted in a request to contribute to the defining of new UV protection standards being developed under the EU Standards, testing and measurement programme. Evidently, co-operative research can have significant impacts beyond its own immediate sphere of activity."

 
Bringing added value
New methods explored
Success in several areas
Broader co-operation
   

Key data

The Growth New materials and production technologies generic research activity focuses on meeting the increasingly complex needs of industry and society with improved processes and products. Fibres with properties that are influenced by their environment form the basis of textiles with interesting protective and accident-prevention capabilities.

Projects

SMARTEX - New functional and smart fibres for technical textile applications (BRPR980669)

     

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