is the n u2014 h bending coupled with c u2014 n stretching ftir spectra of pure plla have no peaks from 1700 to 1500 cm u2212 1 for plla and keratin composite membrane two peaks appeared at 1600 1700 cm u2212 1 and 1550 cm u2212 1 which belong to keratin with increasing of keratin in the composite these two peaks increase correspondingly fig5 plla keratin 1 1 membranes were immersed phosphate buffer saline pbs ph 7 4 at 37 u00b0 c for various time periods up to 4 weeks the degradation medium was changed daily for the first week one at day 10 and day 14 and then weekly for the rest of the remaining period samples were taken out at the end of each sampling time point i e at three hour 1 3 7 14 and 28 days the samples removed from the pbs were first rinsed with distilled water and then vacuum dried for 24 h plla keratin samples before and after degradation were examine by fourier transform infrared ftir and x ray photoelectron spectroscope xps the characterizing peaks of plla and keratin were used to calculate their ratios after different degradation periods along with degradation period the characterization peaks of keratin decreased correspondingly fig6 according to the reducing of absorbance in ftir spectra the change of keratin in composite was calculated fig7 in xps wide scan spectra fig8 it was found that 1 xps spectra of pure plla showed only carbon and oxygen peaks as expected 2 a peak with binding energy at 400 ev corresponding to nitrogen nis was detected it is well known that it is characteristics amino acid residues in the keratin 3 peaks corresponding to n appeared.