Chapter 7 247 the understanding cross-linking within KAPs and possible cross- linking between KAPs and keratins will be necessary to determine which model will best describe the influence of protein structure on the mechanical properties of keratin. Acknowledgements I would like to express my gratitude to Professor Max Feughelman for many hours spent discussing keratin physics over many years. Max has no doubt done more than any other individual to advance our knowledge of the relationships between structure and mechanical properties of wool and hair. I would also like to thank the co-editor of this text, Trefor Evans, for valuable discussions on this chapter and for providing figures as noted within the text. References 1. JB Speakman, The rigidity of wool and its changes with adsoption of water-vapor, Trans Farady Soc, 25, 92-103 (1929). 2. JB Speakman, The Plasticity of Wool, Proc Royal Soc London B, 103, 377-96 (1928). 3. WT Astbury, A Street, X-Ray Studies of the Structure of Hair, Wool, and Related Fibres, I: General, Phil Trans Roy Soc, 230, 75-101 (1932). 4. WT Astbury, HJ Woods, X-ray studies of the structure of hair, wool, and related fibres, II: The molecular structure and elastic properties of hair keratin, Phil Trans Roy Soc, A: 333-94 (1933). 5. WT Astbury, WA Sisson, X-Ray Studies of Hair, Wool, and Related Fibres, III: The Configuration of the Keratin Molecule and its Orientation in the Biological Cell, Proc Royal Soc London, A150, 533-51 (1935). 6. L Pauling, RB Corey, HR Branson, The structure of proteins: Two hydrogen-bonded helical configurations of the polypeptide chain, Proc Natl Acad Sci USA 37, 205-11 (1951). 7. EG Bendit, The a-b transformation in keratin, Nature (London), 179, 535 (1957). 8. EG Bendit, Properties of the matrix in keatins, Part I: The compression testing technique, Textile Res J, 48, 674 (1978). 9. EG Bendit, Properties of the matrix in keratins, Part II: The “Hookean” region in the stress-strain curves of keratins, Textile Res J 48, 717 (1978). 10. BM Chapman, A mechanical model for wool and other keratin fibers, Textile Res J 39, 1102-9 (1969). 11. M Feughelman, BJ Rigby, A two energy state model for the stress relaxation and creep of wool fibres in water, Proc of International Wool Textile Conference, D62 (1955). 12. M Feughelman, A two phase structure for keratin fibers, Text Res J, 29, 223-8 (1959). 13. M Feughelman, The post-yield region and the structure of keratin, Text Res J 34, 539-45 (1964). 14. M Feughelman, The relation between structure and the mechanical properties of keratin fibers, Applied Polymer Symposium, No.18, 757 (1971).