The Science Behind The Technology
The 2BKool technology integrates micro-capsules containing phase-change materials (pcm’s) with a host fabric by injecting the capsules and binders at very high pressure into the fabric structure. The fabric composite is then cured at high temperature in a conveyor oven. This system of binding is unique to Performance Apparel Group and the production equipment was developed in-house in PAG’s South Boston, Virginia factory.
Micro-capsules are hollow polymer shelled spheres which contain the phase change material which absorbs or releases heat. Because the pcm cycles from a solid to a liquid during the cooling or heat absorption cycle it needs the polymer shell to contain the liquid and prevent it from dissipating into the fabric.
One of the most common examples of phase change is that of ice changing to water. Heat storage by water alone is about 1calorie per gram but during the phase change period from ice to water the calorific storage increase is 80 times larger. However using ice water as a pcm has inherent problems eg the phase change occurs at freezing/melting point (0 degrees C). Having the pcm’s directly against the skin can cause vasoconstriction which limits the ability of the body to flow heat through the capillaries to the surface where natural cooling is effected by perspiration. In other words, using ice as a pcm is too cold in relation to optimum skin surface temperature.
2BKool technology uses a substance (instead of water) which relates more closely to the body’s normal operating temperature, melting circa 55-65F and stores around 60 calories per gram. Perspiration aids the recycling process by cooling the capsules as heat is released and can be even more effective if there is extra air flow over or through the fabric.
Where cooling apparel is not used in high stress situations, hyperthermia can occur where perspiration evaporates before it has time to cool the body surface. The 2BKool pcm system slows that process down and greatly assists skin surface temperatures to stay within reasonable limits.