towards fiber swelling on humidification or bleaching.
Upon irradiation and/or bleaching, the hair fiber progressively becomes brittle as evidenced by the increased denaturation temperature (TD). The decrease in average crystallite size and increase in lattice strain upon irradiation/bleaching, an
Fig. 6. DSC scan showing the denaturation temperature of virgin, UV treated (UV50h, etc.), and 1h post-bleached UV treated hair (UVB).
Fig. 7. DSC scan showing the denaturation temperature of virgin, 5h bleached (B5h), and ‘bleached (5h) + UV irradiated’ hair (BUV200h, etc.).
Fig. 8. Typical XRD scan of virgin hair sample.
Table 1 Average crystallite size and lattice strain calculated from W-H plot.
Sample Average crystallite size in Å Lattice strain
Virgin (Ref) 164 0.15 Ref + UV275h 119 0.21 Ref + UV600h 88 0.21 Ref + UV800h 50 0.23 Ref + UV800h + bleach 1h 126 0.19 Ref + bleach 5h 91 0.21 Ref + bleach 5h + UV500h 66 0.22
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