MECHANICAL PROPERTIES OF HAIR 85 that the changes observed in F(1) and IR values for both fibers, immersed and non- immersed in oil, depend only on the small water contents of their respective monolayers. The changes in equilibrium values of F(1)s, IRs, and length values after treatment in the aqueous solutions of salts and urea can, thus, be explained if it is assumed that these chemicals modify the hydrogen-bonding relaxation processes associated with water in this monolayer (4,15,16,19,37). For instance, the large fiber IR increments accompa- nied by small IR hysteresis effects induced by LiC1 and urea solutions in particular (see Figure 6) might be due to their ability to disrupt slightly the hair protein water structure, i.e., their chaotropic action (43,44). The strong hysteresis effects observed in fibers treated with glycerine and propylene glycol might be, on the other hand, due to the solvation of hair proteins once the solvents penetrate, swelling the fiber. Finally, the induced effects of proteins and amino acids on the F(1)s and IRs of hair might result from interaction of the following phenomena: 1) upon diffusion into hair the amino acids increase the number of hydro- philic groups capable of interacting with the hair water-adsorbing sites and 2) in the case of wheat proteins and wheat oligosaccharides, the later substance might form simultaneously a film that reduces the amount of absorbed water by volume exclusion of water molecules. It is noteworthy that similar mechanisms have been invoked to explain water absorption modifications in wool treated with polymer molecules and other compounds containing amino and carboxylic groups (42,46,47). CONCLUSIONS Changes in the forces to extension and length contractions of hair fibers have been shown to take place in a manner that depends on the nature of the immersion systems. Most of these effects are due to the partitioning of components across the fiber-liquid interface. This partitioning might involve several transport mechanisms such as osmosis, diffusion, and migration. Further investigation is being carried out to assess the role of each mechanism and that of the pH solution. It has also been shown that the short decay in force to deform a hair fiber by 1%, F(1), is modified if some liquid system compo- nents remain on the fibers. ACKNOWLEDGMENTS The author is grateful to Kevin F. Gallagher for his valuable criticisms and enthusiastic support throughout the completion of this work. Also the helpful discussions with Herb Eldestein and Roger T. Jones of Croda, England Mario Garcia of Clairol and Philip Miner of Cheseborough Ponds, are gratefully appreciated. REFERENCES (1) C. R. Robbins, "Physical Properties and Cosmetic Behavior of Hair," in Chemical and Physical Behavior of Human Hair, 2nd ed. (Springer-Verlag, New York, 1988). (2) M. L. Garcia and J. Diaz, Combability measurements on human hair, J. Sac. Cosmet. Chem., 27, 379 (1976). (3) G. V. Scott and C. R. Robbins, Stiffness of human hair fibers, J. Sac. Cosmet. Chem., 29, 469-485 (1978).

86 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (4) G. Danilatos and M. Feughelman, Dynamic mechanical properties of a-keratin fibers during exten- sion, J. Macromol. Sci. Phys., B16(4), 581-602 (1979). (5) M. Feughelman, A comment on "Bending relaxation properties of human hair and permanent waving performance,"J. Soc. Cosmet. Chem., 42, 129-131 (1991). (6) M. Feughelman, The mechanism of set in bending ofa-keratin fibers, Proceedings of the 8th International Wool Text. Res. Conf. (Christchurch, New Zealand), V-I, 517-528 (1990). (7) R. Beyak, C. F. Meyer, and G. S. Kass, Elasticity and tensile properties of human hair. I. Single fiber test method, J. Soc. Cosmet. Chem., 20, 615-626 (1969). (8) C. R. Robbins, C. Reich, and J. Clarke, Hair manageability, J. Soc. Cosmet. Chem., 37, 489-499 (1986). (9) M. S. Ellison and S. H. Zeroninan, Tensile properties of aromatically and aliphatically modified wool fibers under alkaline conditions as a function of temperature, Text. Res. J., 55, 201-205 (1985). (10) D. G. Phillips, Effects of humidity, ageing, annealing, and tensile loads on the torsional damping of wool fibers, Text. Res. J., 57, 42-49 (1987). (11) J. R. Cook and B. E. Fleischfresser, Ultimate tensile properties of normal and modified wool, Text. Res. J., 60, 42-49 (1990). (12) J. D. Leeder and R. L. Shishoo, Studies of wrinkling properties of wool fabrics, Text. Res. J., 57, 430--431 (1987). (13) S. Sukigara, R. C. Dhingra, and R. Postle, Physical ageing and annealing in fibers and textile materials. Part II. Annealing behavior of textile materials produced from wool and manmade fibers, Text. Res. J., 57, 479-489 (1987). M. Feughelman and M. S. Robinson, Some mechanical properties of wool fibers in the "Hookean region" from zero to 100% relative humidity, Text. Res. J., 41, 469 (1971). F. J. Wortman, B. J. Rigby, and D. G. Philips, Glass transition temperature of wool as a function of regain, Text. Res. J., 54, 6-8 (1984). F. J. Wortman and S. de Jong, Analysis of the humidity time superposition for wool fibers, Text. Res. J., 55, 750-756 (1985). M. Feughelman, A Note on the water-impenetrable component of a-keratin fibers, Text. Res. J., 59, 739-742 (1989). J. I. Curiskis and M. Feughelman, Finite element analysis of the composite fiber, alpha-keratin, Text. Res. J., 53, 271-274 (1983). J. B. Speakman, The rigidity of wool and its change with adsorption of water vapour, Trans. Faraday Soc., 25, 93-103 (1929). J. B. Speakman, An analysis of the water adsorption isotherms of wool, Trans. Faraday Soc., 40, 7-11 (1944). A. B. D. Cassie, Absorption of water by wool, Trans. Faraday Soc., 41, 459-464 (1945). I. C. Watt and R. L. D'arcy, Water-vapour isotherms of wool, J. Text. Inst., 7, 299-307 (1979). J. J. Windle, Sorption of water by wool, J. Polymer Sci., 12, 103-112 (1956). H. J. White and P. B. Stam, An experimental and theoretical study of the adsorption and swelling isotherms of human hair in water vapor, Text. Res. J., 19, 136-151 (1949). P. Stare, R. Kratz, and H. J. White, The swelling of human hair in water and water vapor, Text. Res. J., 22, 448-465 (1952). K. W. Herrmann, Hair keratin reaction, penetration, and swelling in mercaptan solutions, Trans. Faraday Soc., 59, 1663-1671 (1963). E. I. Valko and G. Barnett, A study of the swelling of hair in mixed aqueous solvents, J. Soc. Cosmet. Chem., 3, 108-117 (1952). N. H. Koenig, Chemical modification of wool in aprotic swelling media, J. Appl. Polym. Sci., 21, 455-465 (1977). I. C. Watt, Kinetic studies of the wool-water system. Part I: The influence of water concentration, Text. Res. J., 30, 443-450 (1960). I. C. Watt, Kinetic study of the wool-water system. Part II: The mechanisms of two stage absorption, Text. Res. J., 30, 6444551 (1960). P. Nordon, B. H. Mackay, J. G. Downes, and G. B. McMahon, Sorption kinetics of water vapour in wool fibers: Evaluation of diffusion coefficients and analysis of integral sorption, Text. Res. J., 30, 761-770 (1960). (32) I. C. Watt, The relation between longitudinal swelling and water sorption by keratin fibers, Text. Res. J., 35, 1072-1077 (1965).