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A key function of clothing
is to keep the wearer warm in the cold, or to be cool in the heat. New
materials and active functionality are taking this role further.
Passive Functions
- Flame
retardance
- Fire
Protection
- Heat
storage and release
- Heat
insulation
Thermal Protection Fabric Nomex
DuPont
Nomex™
is a material used extensively for thermal protection. ‘Nomex on demand’
is a 'smart' material than creates voids within it when the temperature
is above a critical value - it therefore produces increased insulation
when exposed to a high temperature.
Smartskin
SmartSkin™ hydrogel is a technology involving a
hydrophilic/hydrophobic copolymer, which is embedded in an open-cell
foam layer bonded to the inside of a closed-cell neoprene layer in a
composite wet suit fabric with nylon or nylon/Lycra® outer and inner
layers.
SmartSkin absorbs cold water that
has flushed into the suit and expands to close openings at the hands,
feet and neck, preventing more water from entering. Water trapped inside
the suit heats up upon body contact. If the water warms up past a
transition temperature determined by the proportion of hydrophilic to
hydrophobic components, the hydrogel releases water and contracts,
allowing more water to flush through the suit. This passive system
constantly regulates the internal temperature — no batteries or
mechanical action are needed.
Phase Change Materials  Outlast®
temperature-regulating technology effectively recycles body heat,
keeping the wearer’s skin temperature within a comfortable range.
Outlast was first developed for use in astronaut
uniforms and as a protection for instruments against the severe
temperature changes in outer space. The technology is now used in
apparel, footwear, equipment and linens. Outlast is a paraffin wax
compound that is micro-encapsulated into thousands of miniscule,
impenetrable, hard shells. It recycles body heat by absorbing, storing,
distributing and releasing heat on a continuous basis, keeping the
wearer’s skin temperature within a comfortable range.
Cooling Vests
 Cooling
undervests have pockets for inserts of cooling packs and are
arranged to be a light and thin as possible. Cooling lasts for a number
of hours when the inserts need to be refrigerated.
 Aquatex
Industries Inc's Hydroweave® provides extraordinary protection
against heat, actively cooling the wearer through evaporation, and
helping to maintain the core body temperature in high-heat environments.
It is a three-layer design that combines special hydrophilic and
hydrophobic fibers into a fibrous batting core. The batting is
sandwiched between a breathable outer shell fabric and a thermally
conductive, inner lining.
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A new high-tech vest has
been developed to help keep soldiers, firefighters, etc. alive in the
searing temperatures of deserts, mines and major fires. The vest uses a
personal cooling system (PCS), which is based on heat pipe technology
which works by collecting body heat through vapor filled cavities in a
vest worn on the body. The heat is then transferred via a flexible heat
pipe to the atmosphere with the help of an evaporative cooling heat
exchanger. The heat exchanger is similar in principle to a bush fridge
where a cold cloth is put over a container and the temperature drop
caused by evaporation keeps the food cool. It is designed to be worn by
personnel underneath NBC (nuclear, biological and chemical) clothing,
body armor and other protective clothing.
