530 JOURNAL OF COSMETIC SCIENCE DSC '10 • • •XO 0.10 /// -. -.... •. 4 .•' o.• ...... •',., i "- ,'1 I i -o .os T•r•um Figure 1. DSC cu•es for treated hairs and for the hairs without treatment. Bleached without treatment [1] ...... treatment 1 [2] __ treatment 2 [3] Figure 2. DSC curves for treated hairs and for the hairs without treatment. Without treatment Ill ...... treatment 3 [2] ß treatment 4 [3] • duplicate of the analyses performed within the temperature range of 0øC to 200øC (Table I). Table II presents the enthalpy values for water vaporization both from untreated (con- trol) and treated hair. It is apparent that more energy is spent to release water from treated hair than from untreated hair. The amounts of energy required to release water after treatments 1 and 2 were, respectively, 44% and 83% higher than for the control.

HAIR FIBER HYDRATION 531 DSC '101 Y(mV't, Ukng) ,•, •xo 0.14 /'•'•'-'•' • \ o.12 ////• o.io .,• / .._ 'xx'X • ,' / ,--"-" ..... --,. X / / ,-" "-._ •. X 0.08 / .• •" ',. 0.06 • . ' ' • •_,-' •ea: 273.5795 J• • / - '%,• ' '• ,..,• ---• • •• '• ............. "/ • ' ' "-• 0.• / .... • .... •_• [3] o s• • • •o T•r•re • Figure 3. Details of DSC curves for treated and untreated hair. Each curve is an example of the duplicate curves obtained. Bleached without treatment [1] ...... treatment 1 [2] , ß treatment 2 [3] .... DSC '101 J 0.14 0.12 0.10 0.04 Figure 4. Details of DSC curves for treated and untreated hair. Each curve is an example of the duplicate curves obtained. Without treatment [1] ...... treatment 3 [2] ß treatment 4 [3] , ß After the rinse-off treatments 3 and 4, these amounts of energy were, respectively, 17% and 41% higher than for the control. We suggest two hypotheses to explain the increased amounts of energy necessary for the release of water from hair. First, the treatments increase the water content in the fibers. The higher the amount of water attached to the fibers, the more energy will be necessary to release it. Second, the treatments would, in some way, hinder the release of water,