Clevertex - Grado Zero Espace Srl

shell materials are gelatine, starches, cellulose derivatives, polyactides, polyethylenglycols, polyvinyl
alcohols, acrylates, fats and waxes.
The aim is either to progressively release the substance in the microcapsules in order to exercise a
certain function. In this case, perfumes, medicines, depilatories are processed in the textile.
Or else, the substance remains in the capsules exercising its active function from inside; in this case,
PCMs (Phase Change Materials) are incorporated. The substance in the microcapsules is activated by
body heat or by movement.
The substances in the microcapsules will become active under the influence of an environmental
stimulus and in this way they give the textile an ‘intelligent’ character.
There are four release mechanisms to deliver the content of the microcapsule.
The oldest and most common mechanism is by simple fracture of the shell under the influence of a
mechanical stress.
A second possibility is degradation of the shell. This degradation can be caused by dissolution, a
chemical or an enzymatic breakdown of the shell. When the needed environmental conditions are set,
the content of the microcapsule will be released. The deliverance can be perfectly controlled.
The two last release mechanisms are caused by the breaking of the shell upon swelling of the core.
The encapsulated products are in a dried form and they will start to swell when they are brought in
contact with the suitable product. The shell must allow the diffusion of this product into the core.
Products that decompose while encapsulated can swell by a change in osmotic pressure within the
capsule.
The potential of encapsulated phase change materials was first recognised when the US National
Aeronautics and Space Administration (NASA) tried to find a technology to manage the thermal
properties of garments, in particular for the use in space suits. In 1987, Triangle Research and
Development Corporation of Rayleigh, US, whilst working for NASA, encapsulated phase change
materials with the hope of reducing the impact of extreme variations in temperature encountered by
astronauts during their mission in space. For further development the work was licensed to Outlast
Technologies, US, to exploit the technology initially in fabric coatings, which are commercially
available.
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