Fundamental Studies on the Moisture Sorption and Water Permeation Mechanisms of Textiles Including Sports Wears* -Moisture Sorption and Desorption Isothems of Cellulosic Fibers-
【Supercategory:7. DESCENTE SPORTS SCIENCE Subcategory:7.6 Vol.6】
Twelve kinds of cellulosic fiber, including natural, regenerated, and chemically modified fibers, were prepared for measuring the moisture sorption and desorption isotherms at various temperatures from 10 to 50℃ by two types of gravimetric method, a weighing bottle method and a sorption balance method with quartz spring in vacuum.
From the temperature dependence of the sorption isotherms, the excess energy of moisture sorption on the cellulose fibers was found, on the basis of thermodynamics, to be the largest in dry state ranging up to 100 cal/gr of liquid water, and to decrease rapidly down to almost zero with increasing relative humidity up to saturation.
The sorption isotherms at 30℃ were analyzed by BET multilayer adsorption model to discuss the nature of the adsorbed water in terms of the BET parameters, vm, C, and nmax; maximum volume of unilayered-adsorbed water per gr of dry material, bound energy characteristics between adsorbent and water, and a maximum number of adsorbed layers n below which the calculated moisture sorption never exceeds the experimental one. The natures of adsorbed waters with n=1 (Langmuir's unilayered), with nmax≥n>1 (multilayered), and with n>nmax, were examined in comparison with a recent analysis of the adsorbed waters by differential scanning calorimetry, revealing that the waters with n>nmax+2, nmax+2>n>nmax, and nmax>n correspond, respectively, to the bulk free water, freezable bound water, and non-freezable bound water.
DESCENTE SPORTS SCIENCE Vol.6/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
From the temperature dependence of the sorption isotherms, the excess energy of moisture sorption on the cellulose fibers was found, on the basis of thermodynamics, to be the largest in dry state ranging up to 100 cal/gr of liquid water, and to decrease rapidly down to almost zero with increasing relative humidity up to saturation.
The sorption isotherms at 30℃ were analyzed by BET multilayer adsorption model to discuss the nature of the adsorbed water in terms of the BET parameters, vm, C, and nmax; maximum volume of unilayered-adsorbed water per gr of dry material, bound energy characteristics between adsorbent and water, and a maximum number of adsorbed layers n below which the calculated moisture sorption never exceeds the experimental one. The natures of adsorbed waters with n=1 (Langmuir's unilayered), with nmax≥n>1 (multilayered), and with n>nmax, were examined in comparison with a recent analysis of the adsorbed waters by differential scanning calorimetry, revealing that the waters with n>nmax+2, nmax+2>n>nmax, and nmax>n correspond, respectively, to the bulk free water, freezable bound water, and non-freezable bound water.
DESCENTE SPORTS SCIENCE Vol.6/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
Researcher | Hiromichi Kawai, Akira Takaoka, Kazunori Kohata, Mariko Miyagawa |
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University or institution | Department of Practical Life Studies, Faculty of Teacher Education, Hyogo University of Teacher Education |
Keywords
cellulosic fiber, moisture sorption and desorption isotherms