The decrease
in the value of I3 at around 200 h of irradiation (refer to
Fig. 1b), simultaneous with the increased s3, point towards the increased
moisture activity/occupation of free volumes. It has been
shown that endocuticle, CMC, and amorphous matrix of cortex
swell in aqueous media [4]. These water penetrable regions of hair
are the probable sites, as we anticipate, for the existence of free
volume cavities.