Effects of Wearing Footwear Insulated with Phase Change Materials During Moderate Cold Exposure

摘要

Thermal injury to the feet poses a constant threat to military personnel deployed to cold and wet operational areas. Recently, a new type of insulating material that claims to store and release human body heat through a phase change process have appeared on the commercial footwear market. These phase change materials are typically based on parraffinic waxes and are encased in thin (1 micrometer) microcapsules (15-40 micrometers in diameter). For footwear applications the microcapsules can be integrated into a thin, open cell foam, which replaces the traditional fibrous insulation, found in military cold weather boots. In this study, 8 volunteers wore the U.S. Army Intermediate Cold Weather Boot (Control), insulated with Thinsulate(TM) and three prototype boots identical to the Control but insulated with different phase change materials. The basic protocol consisted of walking on a treadmill at 1.34 m/s for 15 min followed by sifting for 70 min at 0 deg C and - 12.3 deg C. Volunteers wearing the Control boot had consistently higher toe temperatures at 0 deg C but the lowest toe temperatures at - 12.3 deg C. Volunteers wearing the prototype boot insulated with ComforTemp Foam(TM) phase change insulation had comparatively high toe temperatures at 0 deg C as well as the highest toe temperatures at - 12.3 deg C.