The Swelling of Human Hair in Water and Water Vapor

Data are presented on the swelling of free and strained hair fibers in water and water vapor. The strained hair fibers were either under constant load or at constant elongation. In some cases rates of swelling are also shown. The swelling isotherms of the free fibers follow the volume changes predicted from density measurements (for wool) except at very high relative humidities. Straining the fiber may either increase or decrease the amount of swelling, depend ing on the type of experiment. An attempt to develop a statistical mechanical model to explain the equilibrium absorption and swelling behavior of a hair fiber is only partly successful. Finally, there seems to be evidence from the rates of swelling to indicate inhomogeneities in the hair with respect to its response to mechanical deformations.