Effect of Fiber Structure on Heat of Wetting of Cotton and Regenerated Cellulosic Fibers

A new calorimeter is constructed to precisely measure the heat of wetting of cotton, regular viscose rayon, high wet strength viscose rayon, and Tencel®. Our purpose is to investigate the relationship between the heat of wetting and structural characteristics of fibers such as crystal and fiber structure, degree of crystallinity, and water absorbency properties (water regain, moisture regain, and bound water content of fibers). Despite its relatively high water regain, cotton has the lowest heat of wetting among the fibers studied so far. The heat of wetting of cellulosic fibers depends slightly on fiber and crystal structure but decreases proportionally with the increasing degree of crystallinity of the fibers. The heat of wetting is closely related to the amount of bound water estimated by differential scanning calorimetry. These results are discussed from the viewpoint of designing high performance cellulose materials.