Molten urea as a novel dissolving solvent for wool and other animal proteins

Abstract

The function of molten urea as the solvent for wool and other animal proteins were investigated. Molten urea at 150 °C could dissolve wool without addition of water or any other chemicals. Also, it could dissolve other animal proteins such as hair, feather and silk. When the concentration of wool in molten urea was up to about 10 %, the recovery of water soluble and water insoluble keratins were determined by 13C-CP/MAS NMR spectroscopy. It was found that the water soluble keratin consists of 61 % β-sheet and 39 % α-helix, and the water insoluble keratin almost consists of β-sheet. The result of nitrogen content assay by elementary analyzer revealed that 9.2 % (w/w) urea par water soluble keratin might form chemical bonds with the keratin.