JOURNAL OF COSMETIC SCIENCE 126 On the other hand, the distance between IFs and the FWHM in the bleached hair were observed in the symmetry with the center of hair shaft as an axis, as expected. Figure 5 shows the results of the analysis for the permed hair and the stretched hair. Al- though distance between IFs in the stretched hairs had no difference with that in the permed hairs, the FWHM in the stretched hair was smaller than that in the permed hair. Figure 6 shows the results of the SLS-immersed hair compared with the permed hair. The distance between IFs and the FWHM in the SLS-immersed hairs was smaller than those in the permed hairs. Figure 7 shows the results of the stretched SLS-immersed hair compared with the permed hair. Although distance between IFs in the stretched SLS immersed hairs had no differ- ence compared with that in the permed hairs, the FWHM in the stretched SLS immersed hair was smaller than that in the permed hair. Thus, the IF orientation was isotropic for Figure 3. Change of scatterin g intensity profi le extracted from the equatorial axis.

STRUCTURAL ANALYSIS OF PERMANENT WAVED HAIR BY SAXS 127 the permed hair with these treatments. As a result, the difference in IFs orientation found between the convex and concave side of the stretched SLS-immersed hairs were narrowed. DISCUSSION The distance between IFs was found to be larger in permed hair compared with bleached hair. This is believed to be because of changes in intermolecular bonds, including disul- fi de bonds, due to the chemicals used in perming. Furthermore, on comparing the convex and concave sides of permed hair, the FWHM were found to be signifi cantly larger on the convex side. This is possibly because IFs exist in different orientations on the concave and convex sides, as it is wrapped around the rod. According to previous research on naturally curly hair using SAXS, lack of homogeneity in IF orientation between the convex and concave sides of the curl plays a major role in affecting hair curl morphology (10). In case of permed hair, anisotropic IF orientation between the convex and concave sides of the curl seemed to be similarly related to macroscopic hair curl. Figure 4. Distance between IFs and FWHM for bleached hair and permed hair. 1: Mean values for the cortex of bleached hair. 2: Mean values for the convex curvature side of permed hair. 3: Mean values for the concave curvature side of permed hair. t-test was used for statistical analysis with *p 0.05, **p 0.01, ***p 0.001. Figure 5. Distance between IFs and FWHM for permed hair and stretched hair. Black fi lled square convex sides and gray fi lled square concave side. t-test was used for statistical analysis with *p 0.05, **p 0.01, ***p 0.001.