The effect of spinning speed on the structure and properties of Bombyx mori silkworm silk

To study the spinning condition of Bombyx mori silkworm, a silking device has been developed to obtain silk fibers by forcibly silking at different spinning speeds. The silking device was very simple and consisted of motor, speed controller, speed counter and a bobbin. The silk fibers were acquired from a Bombyx mori silkworm, N140 x C140 by the described procedure at the speed of 60, 120, 180 and 240 cm/min respectively and its fiber dimensions, tensile properties and structural characteristics were evaluated. The fiber diameter has decreased with increasing the spinning speed. The mean diameter of silk fibers obtained at higher speed (240 cm /min) is 8.0 mu m. The forcibly silk fibers obtained by different speeds showed reproducible qualitative force-displacement curves. The stress-strain curves revealed that the tensile strength of silk fibers obtained at higher speed is significantly increased. The fibers obtained by different silking speeds exhibited a fairly similar X-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber diameter.