The Structures And Properties Of Silk Fiber Prepared By Feeding Method

Bombyx mori silk fiber, is a kind of natural protein materials and has been widely applied in textile, biotechnological, biomedical, food and cosmetic fields due to its excellent mechanical properties, luster, smoothness, comfort and biocompatible properties. Feeding method has the advantages with normal temperature, low energy consumption, high efficiency and low damage etc. This paper focused on the following main researches based by feeding method.Firstly, Silk fibers were produced by feeding Bombyx mori silkworm with mulberry leaves containing superfine down powder. The structure and properties of modified silk were studied and compared with normal silk by scanning electron microscopy, infrared spectroscopy, x-ray diffraction and mechanical properties. Results showed that the molecular conformation of modified silk fiber was β-sheet, and the morphology of raw silk fibers seems to be unaffected by feeding the mulberry leaves containing superfine down powder. The crystallinity of the silkworm fed with modified feed was slightly improved. Additionally, the chemical structure of silk was not changed. It also proved that the crystalline interplanar spacing of silk fibers remained unchanged. With the increase of superfine down powder, the stress of silk fiber enhanced at first and then decreased. However, the mechanical properties was improved dramaticlly when the down powder amount was 4 wt%. Comparing to untreated raw silk fibers, the tensile strength at break of the treated raw silk fibers increased significantly from 0.44 to 0.55 GPa,. Therefore, high strength raw silk fibers could be obtained by feeding the silkworm larvae with a modified mulberry leaves containing superfine down powder.Secondly, Silk fibers were prepared by feeding Bombyx mori silkworm with mulberry leaves containing Fe3O4 nanoparticles. The structure and properties of modified silk were studied and compared with normal silk by scanning electron microscopy, infrared spectroscopy, x-ray diffraction, thermogravimetric analysis and mechanical properties. Black color cocoons were obtained from the Bombyx mori by feeding silkworm with the nanoscale Fe3O4 nanoparticles. Results showed that the moderate content of the Fe3O4 powder had no significant effect on the growth of the Bombyx mori silkworm. The Fe3O4 nanoparticles was embedded in the silk, the crystallinity and mechanical properties of the modified silk were enhanced compared to the normal silk. Moreover, an integration of the amide I band intensities suggested that there was a relatively high content of β-sheets in the modified silk. Compared to the normal silk, it indicated that the main conformation in modified silk was α-helix and β-sheet, and the main structure of modified silk remains unchanged. Silk fiber obtained by feeding silkworm with mulberry leaf mixed with 2 wt.% Fe3O4 nanoparticles exhibited higher strength and slightly batter thermal stability.