Study on Spinning Process of Silkworm by Using Synchrotron Radiation X-ray Diffraction

The spinning process of a fifth instar Bombyx mori silkworm was studied in situ by synchrotron radiation wide angle X-ray diffraction (SR-WAXD). Silk glands dissected out from the larvae, and degummed cocoon silk were also examined by SR-WAXD. The effects of drying and drawing on the development of ordered structure of silk fibroin in the silk gland were investigated. The results show that ordered structures related to silkⅠ and silkⅡ are formed in the spinning dope near the spinneret of the silkworm head. During drying process of the silk gland, dehydration results in the formation of ordered structure of silk fibroin. Its conformation transforms to anti-parallel β-sheet which tends to construct perfect lamellar crystalline structure of silkⅡ during drying. In addition, drawing is another important factor to induce the formation of ordered structure of silk fibroin and resultant fiber.