EFFECT OF POLYMERS AND SURFACTANTS 255 2.5 [] PVP/DMAPA Acrylates Copolymer [] Quaternium 70 [] Hydrolyzed Wheat Protein [] untreated 0.5 o 1.8 4 minutes 8 minutes 12 minutes 1.6 1.4 1.2 0.6 0.4 -I• PVP/DMAPA Acrylates Copolymer [] Quaternium 70 [] Hydrolyzed Wheat Protein [] untreated 0.2 f f o b 4 minutes Figure 8. Stiffness male as •uncdon o• time and subjected to a c•]in• iron for light-brown fibers treated with the indicated compounds of 132øC after rinsing (a) and after shampooing (b). surfactant will suppress an increase in combing forces. Untreated hair, on the other hand, will provide increased combing forces after curling iron exposure, which is most likely associated with the thermal decomposition of the surface lipid layer. Finally, dual- cantilever bending experiments have been employed to probe the variation in the stiff- ness of hair tresses after thermal exposure. The stiffness of the fiber assemblies for both

256 JOURNAL OF COSMETIC SCIENCE unmodified and polymer-treated hair was found to increase as a result of thermal exposure. This may be a result of structural rearrangements in hair, consisting of (a) an increase in the content of the crystalline phase for intact hair, and (b) the addition of adsorbed amounts of polymer, which produce linkages between fibers. REFERENCES (1) P. Milczarek, M. Zielinski, and M. Garcia, The mechanism and stability of thermal transitions in hair keratin, Colloid Polym. Sci., 270, 1106 (1992). (2) L. Rebenfeld, H. Weigmann, and C. Dansizer, Temperature dependence of the mechanical properties of human hair in relation to structure, J. Soc. Cosmet. Chem., 17, 525 (1966). (3) W. Humphries, D. Miller, and R. Wildnauer, The thermomechanical analysis of natural and chemi- cally modified human hair, J. Soc. Cosmet. Chem., 23, 359 (1972). (4) R. Arnaud, G. Perbet, A. DeFlandre, and G. Lang, ESR study of hair and melanin-keratin mixtures-- The effects of temperature and light, Int. J. Cosmet. Sci., 6, 71 (1984). (5) R. McMullen and J. Jachowicz, Thermal degradation of hair. I. Effect of curling irons,J. Cosmet. Sci., 49, 223-244. (6) R. Crawford, C. Robbins, and K. Chesney, A hysteresis in heat dried hair, J. Soc. Cosmet. Chem., 32, 27 (1981). (7) S. Shah, EP 0 681 826 A2, 1995. (8) Kobayashi Kose KK, JP 3 135 909 A, 1991. (9) Lion Corp.,JP 3 291 211 A, 1991. (10) Sunstar KK, JP 3 157 316 A, 1991. (11) Lion Corp.,JP 57 206 605 A, 1982 Chem. Abstr., 98, 362 (1983). (12) KAO Corp.,JP 6 206 808 A, 1994. (13) Sunstar KK, JP 60 116 624 A, 1983. (14) R. Galleguillos and D. Bhatt, US Patent 5 639 448, 1997. (15) A detailed description of the cantilever bending assembly is included in a manuscript which will be submitted for publication (1998). (16) J. Jachowicz, M. Helioff, C. Rocafort, A. Alexander, and R. Chaudhuri, Photodegradation of hair and its photoprotection by a substantive photofilter, DCI, 157, 28 (1995). (17) M. Garcia and J. Diaz, Combability measurements on human hair, J. Soc. Cosmet. Chem., 27, 379 (1976). (18) L. Wolfram and D. Underwood, The equilibrium between the disulfide linkage in hair keratin and sulfite or mercaptan, Textile Res. J., 36, 947 (1966).