in just 200 h of irradiation time i.e. only about one-third of the time needed in the case of virgin hair. Thus, here also, cross-linking forces the polymer segments to come closer and this effect
Fig. 2. Effect of humidification and bleaching on o-Ps lifetime s3 and intensity I3 of UV irradiated virgin hair sample. Here, UV200h represents a 200h UV irradiated hair; UV200hW is a 200h UV exposed + humidified hair; UV800hB is a 800h UV exposed + bleached (1h) hair.
Fig. 3. Variation of (a) o-Ps lifetime s3 (free volume hole size Vf), (b) o-Ps intensity I3, and (c) fractional free volume Fv as a function of bleaching time.
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