Investigation of Comfort of Underwear Made of Mixed Polypropylene Fabric When Warming Up

The purpose of this study is to evaluate the wearing comfort of polypropylene (PP) clothes thorough measuring material properties and physiological and psychological responses. PP fiber has low thermal conductivity, is hydrophobic, and has a lighter specific gravity. These features are useful in a clothing material. PP fibers have attracted much attention in the apparel industry. We assumed that PP is a good material for a comfortable warm-up underwear, since PP clothes would prevent the decreases in skin surface temperature when perspiring. Material properties measurement were made according to Kawabata Evaluation System (KES) and Japan Industrial Standards (JIS). We examined the characteristics of the samples, and then narrowed down the samples by cluster analysis for the clothing experiment. After that, we conducted an experiment measuring the physiological and psychological responses in the state of wearing a sample while warming up the lower limb. Physiological response measurements were electrocardiogram (ECG), respiration, and the temperature and humidity in the clothes. Psychological response measurements were by semantic differential method and ranking method. We calculated LF/HF as an indicator of autonomic nerve activity by ECG. Then we created a comfort indicator called SAC from the LF/HF and humidity in clothes. Order by ranking method corresponds with ranking by SAC. We concluded that PP clothes are comfortable when perspiring.