Clarity of films from wool keratin

The keratin in wool is a highly crosslinked protein. The high molecular wei ght, crosslinked structure prevents its shaping into films without extensiv e decomposition. Since the crosslinks are -S-S- bridges, reducing agents ca n break them up, resulting temporarily in lower molecular weight polymers. In this work, wool fibers are pretreated with an aqueous solution of variou s reducing agents to open the disulfide bonds, and then pressed into films at 130-150 degrees C and pressures of 41.7-66.7 MPa in a hydraulic press. T he optimum conditions to obtain clear, transparent films include using Na2S O3 in aqueous alcohol solutions before pressing 135 degrees C and 55.6 MPa.