Structural characteristics and properties of Bombyx mori silk fiber obtained by different artificial forcibly silking speeds.

To study the spinning condition of natural biopolymer silk, the silk fibers were directly acquired from Bombyx mori silkworm, N140 x C140 by a simple artificial forcibly silking method at the speed of 60, 120, 180 and 240 cm min(-1), respectively and its microstructure and physical properties were evaluated. The fine silk fibers (about 8 microm) were obtained at faster spinning speed, 240 cm min(-1). The tensile properties of silk fibers were remarkably increased with raising the forcibly spinning speeds. The beta-sheet structure contents of silk fibers obtained at higher speed were considerably increased. The fibers obtained by different spinning speeds exhibited a fairly similar X-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber diameter. The fine silk fibers obtained at higher speed (240 cm min(-1)) exhibited a slightly higher thermal stability, as shown by the upward shift of differential scanning calorimetry (DSC) decomposition temperature.