Drawing of Silk Fibroin Fibers Treated with LiBr Aqueous Solution.

Abstract

Mechanical and structural changes of silk fibers caused by stretch after treatment with LiBr aqueous solution were investigated. The mechanical properties of degummed silk depended upon the temperature of treatment with 8M LiBr aqueous solution. The strength and elongation increased with treatment temperature whereas the Young's modulus decreased. The X-ray diffraction pattern showed that the crystalline orientation was disturbed by the treatment at 80°C whereas the destruction of the crystallites did not occur. The stretch up to 160% was possible after the treatment at 80°C for 1h in 8M LiBr aqueous solution. The strength and Young's modulus increased while the elongation decreased. On the basis of the X-ray diffraction and SEM observations, the crystal orientation was found to become higher with increasing draw ratio.