While there are numerous conventional methods of clothing construction which give insulation against the cold there are no conventional clothing constructions, those without some mechanical cooling devices, which allow for comfortable thermal protection when used in hot environments. The special apparel which may be used as protection in hot environments are usually extremely uncomfortable and bulky or even stiff. With the use of microencapsulated phase change materials incorporated into man-made fibers or topically applied to, or impregnated into, various fabric or foam substrates it is possible to use more conventional garment constructions and have thermal protection built into the garment. Phase change materials are compounds or blends of compounds which either absorb or release a large amount of energy in a relatively small temperature range while they are changing phase. The oldest and still most commonly used phase change material is frozen water or ice. Ice is used to cool drinks and other materials because it has the ability to absorb a large amount of energy into it with only a very minor change in temperature, while it goes through a phase change, or melts, at around 0°C. The objective is virtually identical for the application of phase change materials within thermal protective garments or accessories; one wants to use these materials to create a thermal "barrier" or "hurdle" as a deterrent from reaching certain elevated temperatures which may be harmful or even deadly to the wearer.
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