Research On The Factors Which Affect The Structure And Performance Of Natural Color Silk

Natural color silk is a kind of silk which use the natural color cocoon genes chosen from all over the world, the color of it is stable. It can not only avoid the danger brought by the chemical dyes, but also can avoid the pollution produced by the dyeing factory, so it is a new kind of silk which is worthy to be exploited.Infrared spectroscopy, X-ray diffraction, amino acid analysis, scanning electron microscope, thermogravimetric analysis,mechanical properties test are used to compare the structure, appearance and property between the natural color silk and the ordinary one. The results show that the natural color silk fiber is thinner than the ordinary silk, the shapes of section and verticality are almost the same as the ordinary silk, the crystallinity of natural color silk is 44.4%, it is lower than the ordinary one; the natural color silk is composed of GLY, ALA, SER and TYR, it is the same as the ordinary one; the percentage ratio of this four amino acids is 86.87%. Amide I, amide II, amide III and amide V exist in natural color silk fibroin molecules; the natural color silk has the structure of random coil,β-sheet andα-helix. The average breaking tenacity of the natural color silk is 3.45cN/ dtex, the Young's Modulus is 76.7 cN/dtex, Breaking Elongation is 17.5%.The influence of chemical agent and thermal to the natural color silk are studied in this article. The results show that the conformation of the treated natural color silk fiber is stillβ- fibroin, withβ-sheet andα-helix structure.The influence of acid is relatively small; the breaking tenacity and breaking alongation of natural color silk declines clearly after Sodium hydroxide treatment; the crystallinity decreases significantly; the Young's Modulus of natural color silk declines a little; the breaking tenacity and breaking alongation of natural color silk treated by oxidants and reducing agent remarkably declines. There are someβ-sheet changed into random coil after treated by metal salt, oxidants and reducing agent. The breaking tenacity and breaking alongation of natural color silk decreases significantly by high temperature and long time treating ,so is the crystallinity.