Studies on the supercontraction of sound and weathered wool and mohair fibers have thrown further light on the mechanism of this reaction. It is concluded that the second stage of supercontraction results from the exposure of sterically protected hydrogen bonds. This can occur through disulfide exchange in the highly cross-linked zones of the microfibrils. Some of the cystine cross-links are stabilized by weathering so that disulfide exchange is inhibited, and hence much less contraction occurs.
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