AbstractThe dynamic modulus and loss angle of keratin fibers have been measured during changes of relative humidity at a fixed fiber strain, temperature, and frequency of oscillation. From these measurements and the observation of an overshoot in loss angle in particular, certain conclusions about the structure of fibers can be made. This overshoot during absorption can be attributed to an interaction between two phases of keratin fibers. When a fiber at a fixed strain is dried from the wet state, the amount of α helices that have opened up during extension in water remains practically constant. A fiber that has been extended in the dry state contains α helices which open more rapidly than in the wet state for a given strain and rate of strain. When a wet fiber is dried and then rewetted while it is held at a fixed strain, the fiber achieves essentially the same structural state as in its original strained stat
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