Changes of Curvature with Regain of Set Wool and Hair Fibers

The study investigated how moisture affects the curvature of set Merino wool and human hair fibers. It was found that Merino wool fibers' curvature changed significantly with moisture content, with a mean curvature change of 49% at lower strain and 82% at higher strain. Human hair fibers, however, showed no significant change in curvature with strain level. Fiber diameter and tension during winding did not significantly affect the results for either fiber type. The study suggests that Merino wool fibers change curvature due to different swelling rates in their orthocortex and paracortex, similar to bimetal strips in response to temperature, while human hair curvature changes are attributed to radial swelling. These findings help understand the behavior of fabrics made from fibers like Merino wool.