Moisture sorption properties of a hydrophobic fiber of poly (ethylene terephthalate) (PET) and a hydrophilic fiber of nylon 6 were investigated by means of the calorimetry of heat of moisture sorption, the near infrared spectroscopy of sorbed water, and the analysis of moisture sorption isotherm in terms of some physical models, all to emphasize a dual mode of moisture sorption characteristics in PET fiber in contrast to a single mode of sorption characteristics in nylon 6 fiber.
　The heat of wetting of PET fibers at dryness, though being much smaller in magnitude than those of the hydrophilic fibers of nylon 6 and viscose rayon, was found to be a dual mode of endotherm followed by exotherm in contrast to a single mode of exotherm for the hydrophilic fibers. Change in the dual mode of heat of wetting with chemical and physical modifications of PET fiber was demonstrated to understand the origin of the endothermic process for developing a new type of sports textiles.

DESCENTE SPORTS SCIENCE Vol.9/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE