Studies on regenerated protein fibers .3. Production of regenerated silk fibroin fiber by the self-dialyzing wet spinning method

The spinnable dope containing 20 wt % of silk fibroin dissolved in the MU solvent (e.g., LiBr . H2O = 40 wt %, and EtOH : H2O = 100:0 in volume) was spun into a coagulant and subsequently drawn, to give the following results. 1. Methanol, ethanol, and isopropanol were a predominant coagulant for the dope, and the coagulant containing 10% LiBr . H2O is best. 2. Spinnability depended upon the ratio of nozzle hole length to diameter (L/D) and was improved by increasing L/D from 4 to 10. Coagulativity was not sufficient at the SF concentration of 16%, but improved by raising it up to 20%. Drawability of the spun filaments in water was improved at a temperature above 60 degrees C. 3. The drawn fiber showed excellent mechanical properties, especially tensile toughness when as-spun fiber was drawn in water at 61 degrees C. An X-ray diffraction diagram of the drawn fibers indicated their crystalline axes were partially oriented along the fiber axis. (C) 1996 John Wiley & Sons, Inc.