吸放湿繊維材料の水蒸気吸脱着に伴う熱量変化及び発生機構の分析

抄録

In this report, we look at the change in heat quantity and the heat-generating mechanism in moisture-adsorbing/desorbing fiber materials, associated with adsorption and desorption of water vapor. As the moisture-adsorbing/desorbing fiber materials, use was made of a salt of a polyacrylic acid fiber (hereinafter as “AF-Na”) whose starting material was an acrylic fiber and which had a highly crosslinked structure, and a polyacrylic acid fiber (hereinafter as “AF-H”) in which almost all functional groups in a salt of an acrylic fiber were substituted with carboxylic acid. We conducted an experimental study on the change in quantity of adsorption/desorption heat associated with adsorption and desorption of water vapor in these materials, along with the change in the relative humidity. For these materials, we calculated the quantity of adsorption/desorption heat per functional group and the quantity of heat per gram of adsorbed/desorbed water vapor. Generally, the adsorption energy of water vapor is assumed to be equal to its condensation energy. In this context, however, we assumed that the adsorption heat of water vapor was equal to the sum of a water condensation heat and a hydrogen bond-derived energy. Further, we similarly measured the adsorption heat in cellulosic fibers and wool, estimated the adsorption heat and the heat quantity per gram of water vapor on a hydrophilic functional group constituting a natural fiber, and compared the results with those on the functional groups in AF-Na and AF-H. Consequently, the functional group which showed the greatest adsorption heat was found to be the carboxylic salt. Regarding the hydrogen bounding pattern, hardly any difference was found among the carboxylic acid function, hydroxyl group and the carboxylic salt function.