Preparation and Application of Soluble Wool Keratin

Abstract

Soluble wool keratin was prepared by derivatization of disulfide (SS) bonds of cystine residues to carboxymethyl alanyl disulfide (CMAD) groups using thioglycolic acid (TGA). The solubilization reaction was carried out in 0.2M TGA aqueous solution at 30°C for 1 to 24 h under alkaline conditions (pH = 11-13). The yield increased with increase of pH and reaction time. However, the yield decreased when soluble wool keratin was prepared in pH = 13.0 systems for 24 h. Electrophoresis patterns of soluble wool keratin were similar to that of raw wool regardless of reaction time. However, electrophoresis pattern of soluble wool keratin prepared in pH = 13.0 systems for 24 h tended to smear at high molecular weight region. Fourier transform infrared (FT-IR) spectra of soluble wool keratin showed absorption of the associated carboxylic acid due to CMAD groups. Regenerated wool keratin films were prepared from soluble wool keratin by the solution casting method. FT-IR spectra of film were similar to that of raw wool. Thermogravimetry-differential thermal analysis (TG-DTA) revealed a higher thermal stability of films and regeneration of SS bonds between keratin molecules in the films. Flexible films were obtained by addition of glycerol. The elongation of films significantly increased with increase of glycerol content.