Clevertex - Grado Zero Espace Srl

Fig. 95 PCM microcapsules coated on the surface of fabric and embedded within fibre
As a partner of Outlast, Accordis, formerly Courtaulds Fibres, together with Ciba developed an in-fibre
variant of the Outlast microcapsules, which are incorporated by 5-10% in an acrylic fibre. This is
achieved by using the late injection technology [177, 178, 179].
PCM capsules are now particularly applied to outdoor wear and in the household in blankets, duvets,
mattresses and pillowcases. As well as being designed to combat cold, PCM encapsulated in textiles
can help to combat overheating.
2.4.2 Technology
Phase Change Materials (PCM) change their state of matter at a certain temperature: from liquid to
solid and vice versa. When the temperature rises, the excess heat is stored. When the temperature
falls, the previously stored heat is released again.
When a PCM changes from a solid into a liquid state, one can distinguish between three phases
during this process:
1. activation energy is supplied
2. this energy is absorbed and used to break the molecular bonds in the solid structure. The
material’s temperature remains constant until the phase transformation is completed.
3. the substance becomes liquid and the materials temperature starts to increase
Phase change materials mostly find their application as thermal control/regulation materials due to
high latent heat absorption and release which occurs upon phase changing without changing, or only
little, in temperature.
In the textile sector, usually combinations of different paraffin waxes are used. These are
hydrocarbons with different chain lengths and thus different melting and crystallization points. With
changing the proportionate amount of each paraffin type, the melting and crystallization can be
altered. In table 2 different paraffin waxes with their crystallisation and melting points, as well as their
latent heat fusion are presented.
Phase change material Crystallisation point
(°C)
Melting point (°C) Latent heat of fusion
(cal/gm)
licosane 30.6 36.1 59
octadecane 25.4 28.2 58
heptadecane 21.5 22.5 51
102