Raman spectroscopy, FT-IR and XRD were used to analyze themolecular structure changes of keratin modified by lipoic acid.Raman Spectroscopy of Keratin. Fig. 7(a) shows the Raman spectra of different samples, it can be seen that the peak positions ofwool fibers and regenerated keratin films (KF, LKF) were similar.The characteristic peaks of disulfide bonds were mainly distributedin the range of 500–600 cm&1 in Raman spectrum, and differentconformations formed absorption peaks appeared in different positions. According to literatures [39–41], the Raman characteristicpeak of disulfide bonds was not only affected by the ASASAmolecular conformation, but also related to the dihedral anglechanges of ACASASACA and ACACASASA segment. When thedihedral angle of ACACASASA segment in molecular structurewas ±90! or 180!, the characteristic peaks of disulfide bonds willbe located near 510 cm&1. If the dihedral angle changed significantly, the peak will move to the range of 525–540 cm&1 [4