Clevertex - Grado Zero Espace Srl

Fig. 110 Flap opening in the textile structure [195]
The project has been chosen as one of eight to represent United Kingdom science at Expo 2005 in
Japan.
Fig. 111 ........Temperature regulating jacket exhibited at EXPO 2005
Another example of fabrics that change their performance in response to moisture is textiles coated
with a polyurethane film. The company Baxenden Chemicals has developed a hydrophilic
polyurethane coating for textiles that becomes more breathable, the more moisture is build up inside
the clothing. In general, a solid, hydrophilic polyurethane coating constantly adapts to surrounding
conditions of water vapour pressure. Their resistance values decrease with the amount of water
contained in the polymer. In extreme cases, when liquid water is in contact with the polymer surface,
hydrophilic polyurethanes reversibly absorb up to three water molecules per ethylene oxide unit and
may become swollen. In this state water vapour transport through the molecular network is enhanced
and the diffusion coefficient increases [58].
Researchers at the Indian Institute of Technology succeeded in developing a smart breathable cotton
fabric coating which responds to changes in ambient temperature. They used a temperature sensitive
copolymer-poly (N-tert-butylacrylamide-ran-acrylamide). The coating on the fabric shows a retained
temperature-sensitive swelling behaviour and a transition in the temperature range of 15-40°C. Below
15°C, the coating swells by 800% while above 40°C it deswells to a swelling percentage of less than
50% (on the basis of dry weight). The response was found to be reversible and stable to repeated
cycles of transition [196].
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