Clevertex - Grado Zero Espace Srl

fibroin, keratin and collagen, dried, crimped, dipped again in water and thermo-set in the wet state
under high pressure at 110°C for ten minutes, yielding shape-memory silk. As the twisted structure is
stored in the memory, the silk yarn reversibly recovers its curled shape by steaming after it has been
untwisted and uncurled. The silk yarn can be applied in various textile products, like outer garments,
tights and knitted yarns [140].
2.5.2 Applications in the clothing sector
2.5.2.1 Research projects and products
Alloys
In practice, a shape memory alloy is usually in the shape of a spring. The melting point of this alloy lies
around 1340°C, which makes it extremely suitable for protective clothing. The Ni-Ti relation is chosen
in such a way that the springs are flat in unheated condition, in other words at room temperature. Due
to the low shift modulus, they can easily be opened. Thus, at increasing temperatures the springs will
open up. This results into a considerable increase of the shift modulus, which makes it difficult for
them to close. The springs only have a one-way function: when cooling down, they will not regain their
original shape. When the springs are used in heat-resistant clothing, the garment cannot be used
again once it is being exposed to the heat.
The pioneering UK Defense Clothing & Textiles Agency (DCTA R&TG) in this field created an
intelligent suit suitable for protective clothing for firefighters at the end of the nineties. It consists of two
separate layers, in which cotton bands are introduced in order to incorporate the springs. The springs
are only fixed at the outside layer, so that they are minimally obstructed when expanding. The springs
used are conic and have a 25mm diameter. Air is a good insulator. Under the influence of the
transformed springs, both textile layers will move away from each other as a result of which an
insulating air layer is formed between them.
A doll wearing the garment is exposed for 8seconds to a propane burner, emitting an 80kW/m² flux of
warmth. Because of the heat, the springs open up and create an insulating air layer between both
textile layers.
The results of this test set-up were very satisfactory. For comparison, at the backside of the doll,
where no springs were attached, burns in the second and the third degree were found.
The inner layer used: a Proban ® - cotton woven
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