2006 TRI/PRINCETON CONFERENCE 391 CONCLUSIONS It was observed that changes in the hair mechanical properties are mainly related to the UVB range of the solar spectrum and that UV A radiation is the one responsible for color changes, disregarding the hair type. Color changes depend on hair type, being more pronounced for light colored hairs. Although lightening every hair type is the main effect of radiation, significant variations in all color parameters are observed after lamp irradiation. The susceptibility of different hair to photodegradation is not only related to the melanin type and content of each hair, though also with the overall hair fiber structure. ACKNOWLEDGMENTS The authors thank FAPESP (Grants 01/14161-9 and 04/13066-0), CNPq, CAPES and Cognis Brasil Ltda. for financial support. REFERENCES (1) C.R.Robbins and R. J. Crawford, Cuticle damages and the tensile properties of human hair,]. Cosmet. Sci., 42, 59-67 (1991). (2) P. Zuidema, L. E. Govaert, F. P. T. Baaijens, P.A. J. Ackermans, and S. Asvadi, The influence of humidity on the viscoelastic bahaviour of human hair, Biorheol., 40, 431-439 (2003). (3) W. L. Cheun, The chemical structure of melanin, Pigment Cell Res., 17, 422-424 (2004). (4) G. Prota, Melanins and Melanogenesis (Academic Press, London, 1992). (5) P. Z. Margalith, Pigment Microbiology (Chapman and Hall, London, 1992). (6) Z. D. Draelos, The biology of hair care, Dermatol. Clinics, 18, 651-658 (2000). (7) S. B. Ruetsch, Y. Karnath, and H. Weigmann, "Photodegradation of Human Hair: A Microscopy Study," in Sun Protection in Man, P. U. Giacomoni, Ed. (Elsevier, Amsterdam, 2001), pp. 175-205. (8) C.R.Robbins, Chemical and Physical Behavior of Human Hair (Springer-Verlag, New York, 2002). (9) C. M. Pande and J. Jachowicz, Hair photodamage: Measurement and prevention,]. Soc. Cosmet. Chem., 44, 109-122 (1993). (10) E. Tolgyesi, Weathering of hair, Cosmet. Toiletr., 98, 29-33 (1983). (11) S. Ratnapandian, S. B. Warner, and Y. K. Karnath, Photodegradation of human hair,]. Cosmet. Sci., 49, 309-320 (1998). (12) A. C. S. Nogueira and I. Joekes, Hair color changes and protein damage caused by ultraviolet radiation, ]. Photochem. Photobiol. B: Biol., 74(2-3), 109-117 (2004). (13) C.R. Borges, J.C. Roberts, D. G. Wilkins, and D. E. Rollins, Relation of melanin degradation products to actual melanin content: Application to human hair, Anal. Biochem., 290, 116-125 (2001). (14) A. Bertazzo, M. Biasiolo, C. V. L. Costa, E. C. Stefani, and G. Allegri, Tryptophan in human hair: Correlation with pigmentation, Il Farmaco, 55, 521-525 (2000). (15) M. R. Vincensi, M. d'Ischia, A. Napolitano, E. M. Procaccini, G. Riccio, G. Monfrecola, P. Santoianni, and G. Prota, Phaomelanin versus eumelanin as a chemical indicator of ultraviolet sensitivity m fair-skinned subjects at high risk for melanoma: A pilot study, Melanoma Res., 8, 53-58 (1998).

J. Cosmet. Sci., 58, 393-404 Quly/August 2007) Evaluation of hair humidity resistance/moisturization from hair elasticity TIMOTHY GAO, Croda Inc., 300-A Columbus Circule, Edison NJ 0883 7. Synopsis Average water regain and hair elasticity (Young's modulus) of virgin dark brown and bleached hair fibers under different relative humidity (RH) were determined. It is observed that hair water regain increases linearly with an increase in RH in the range of 40-85% and the remaining percent of hair elasticity decreases linearly with an increase in RH in the range of 50-80%. Therefore, measurements of average hair elasticity at 50% and 80% RH, respectively, under various equilibrium times before and after cosmetic treatments can be used to evaluate effects of cosmetic treatments on water adsorption behavior of hair- improvement in hair humidity resistance or enhancement in hair moisture uptake. A Hair Humidity Resistance Factor (H2RF) has been defined. If R2HF 1, the product improves hair humidity resistance-anti-frizz if R2HF 1, the product enhances hair water adsorption when R2HF - 1, the product has no significant effect on hair water adsorption behavior. This method was applied to evaluate anti-frizz performance of several shampoo formulations containing Polyquaternium-10, or Polyquaternium-70, or Polyquaternium-67, or Guar Hydroxypropyltrimonium Chloride. It was found PQ-70 shampoo showed the highest H2RF value and the best anti-frizz performance among these tested shampoos. The results were consistent with those obtained from Image Analysis. INTRODUCTION It is well known that the tensile mechanical properties of hair fibers, with respect to fiber extension under small deformations ( 2%), are related to the moisture level within the hair fiber. Water molecules are capable of penetrating into hair and plasticizing the components of hair fibers, and as such the force required for a given extension length is reduced with an increase in moisture content of hair. The exhibited behavior of hair fibers in low and high humidity environment is markedly different. At low humidity the hair fiber demonstrates low plasticity/flexibility. Me- chanical agitations such as combing, styling etc. can lead to significant fiber damage and hair breakage. Conversely, at high humidity the hair fiber may suffer the alternate extreme, that is the fiber becomes over plasticized and limp leading to poor hold/style retention. Especially, untreated naturally curly hairs are in frizzy condition and become unmanageable-"frizz" at high relative humidity. Therefore, reduction of the differences in mechanical properties of hair fibers at low and high relative humidity, i.e. remaining higher moisture content at low RH environment and reducing moisture uptake at high RH environment should lead to significant improvements in hair strength, texture, style retention and reduction of split ends. 393