710 JOURNAL OF COSMETIC SCIENCE (30) I. Sopyan, R. D. Permata, D. Gozali, and I. S. K. Syah, Formulation of lotion from black tea extract (Camellia sinensis Linnaeus) as sunscreen, Int. J. Appl. Pharm., 11(1), 205–209 (2019). (31) S. L. Davis, J. M. Marsh, C. P. Kelly, L. Li, C. S. Tansky, R. Fang, and M. S. J. Simmonds, Protection of hair from damage induced by ultraviolet irradiation using tea (Camellia sinensis) extracts [published online ahead of print 20 Aug 2021], J. Cosmet. Dermatol., doi: 10.1111/jocd.14387. (32) K. Kizawa, H. Troxler, P. Kleinert, T. Inoue, M. Toyoda, M. Morohashi, C. W. Heizmann, Characterization of the cysteine-rich calcium-binding S100A3 protein from human hair cuticles, Biochem. Biophys. Res. Commun.,299(5), 857–862 (2002).

711 Address all correspondence to Roger L. McMullen, rmcmullen@ashland.com Physicochemical Properties of Textured Hair ROGER L. MCMULLEN, TIMOTHY GILLECE AND TYLER SCHIESS Ashland LLC, Bridgewater, New Jersey, USA (R.L.M., T.G., T.S.) Synopsis In this study, we investigated differences in the various properties of textured hair as compared to straight hair. As representative hair types from both ends of the spectrum, we investigated the morphological and ultrafine structural characteristics of African and Caucasian hair. We took a profound look at African hair using field emission scanning electron microscopy (FESEM), examining the exterior of the fiber as well as its interior structure by analyzing thin cross-sections of hair. We found that it has unique morphology in both the exterior and interior of the fiber. Some key features include the fiber morphology at a point of curvature, concavity in the major axis, large distribution of melanin granules, and fibrillar structures (keratins) heavily coated with biological material (presumably lipids). We further examined the lipid characteristics of African and Caucasian hair using Fourier transform infrared imaging to map the lipid distribution within the cross- section of hair. Using dynamic vapor sorption, we observed the effect of lipid distribution in African hair and its influence on water management properties. Finally, tensile strength data (break stress, percentage extension at break, etc.) agreed with data previously published in the literature. Expanding on this theme, we monitored the fracture patterns of fibers extended to break using FESEM. Overall, African hair was found to exhibit various types of fracture patterns, especially at the point of curvature of the fiber. The structures of the broken fibrillar proteins (intermediate filaments) were significantly longer in Caucasian hair than in African hair. INTRODUCTION Textured hair refers to hair types that have some degree of curl, twist, wave, or coil associated with them. Hair from African descent, which is the most elliptical of all human hair types, represents one limit of the textured spectrum. Some types of Asian or Caucasian straight hair, which have more circular cross-sectional shapes, are at the other limit of the texture spectrum. Hair from various ethnicities or racial origins have unique physicochemical properties (1–5). For example, African hair has a lower radial swelling rate than Asian and Caucasian hair. In terms of mechanical (tensile) properties, it is generally found that the stress and elongation at break is lower in African hair than in Asian and Caucasian hair (6). The fracture point of the fiber in African hair during tensile measurements can occur in the twist or homogenous region of the fiber, although it more often appears in the twist region (7). African hair fibers with a larger diameter tend to have looser curl, while fibers with J. Cosmet. Sci., 72, 711–731 (November/December 2021)