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Abstract
A recently derived physical structure for wool keratin is discussed and found to be compatible with a wide range of physical data. Formulae are presented that enable the phase concentrations at different extensions to be calculated. Analysis of the stress–strain curves of wool in water permits the separation of the stress into two principal components, due to the matrix and microfibrils, respectively, and an estimate of hydrogen-bond strengths in the α-helix is made. Both supercontraction and stress-deformation observations are considered, and found to be in agreement with the model. A structure for the wool-keratin protofibril consisting of a triplet of Pauling-type α-helices in series with extended β-chains is further discussed, particularly in relation to the α-β transformation.