Modification Of Silk Fibers And Fabrics Treated With Nano-chitosan And Nano TiO₂-chitosan

The two nano-materials dispersion system of natural organic macromolecular nano-chitosan and composite of nano-TiO2 and chitosan were prepared based on the idea of green chemistry and ecological textiles in this dissertation. The purpose of this work is to make full use of special properties of nano-particles, chitosan and TiO2 to overcome the weak point of silk fibers and fabrics.Nano-chitosan dispersion system was prepared with low molecular weight chitosan (viscosity average molecular weight is 2.1×104) according to the mechanism of ionotropic gelation action, and nano-TiO2 and chitosan dispersion system was prepared with sol-gel method using tetrabutyl-titanate as a precursor, the precursor was first made into stable nano-TiO2 sol, and then the sol TiO2 was dispersed into acid solution of chitosan homogeneously. The factors that affected nano-particles sizes including usage of the contents in the system, pH value, preparation temperature were discussed, and the optimum preparation technology was determined. Then the formation mechanism and dispersed state of nano-chitosan and nano-TiO2/chitosan were analysized by means of modern analysis of the laser size detector and transmission electron microscope. The average diameter of the prepared low molecular nano-chitosan was 20.82nm, and the polydispersity index was 0.43. The average diameter of nano-TiO2 and chitosan was 36.71nm, and the polydispersity index was 0.46.The structures of Bombyx mori (B. mori) silk and tussah silk fibers treated with nano-chitosan and nano TiO2-chitosan were studied systematically by Fourier transform infrared microspectroscopy ( FT-IR), X-ray diffraction (XRD), thermal analysis and X-ray photoelectron spectroscopy (XPS) analysis. It was found that the interior structure of the two treated silk fibers tended to formβ-structure, and the crystallinity and thermal stability increased at the same time. Furthermore, the covalent crosslinking reaction occurred among silk fiber, citric acid and chitosan.The mechanical properties, dyeing properties, wrinkle-resistant perfo rmance and anti-bacteria performance of B. mori silk and tussah silk treated with the two nano-materials were tested. It was found that the breaking strength, breaking elongation, Youngs modulus, rupture work, elasticity and immediate-elasticity of the two silk fiber increased; the dyeing uptake and depth of acid dyes, the dyeing uptake fixation and depth of reactive dyes, the dyeing depth of sorghum red natural mordant dye improved; the wrinkle-resistant performance of immediate-elastic and delay-elastic crease recovery angle of the treated silk fabrics improved. The modification of the two silk fabrics gives high anti-bacteria properties to bacillus coli and staphylococcus aureus, the bacterial reductions were all more than 85%.The dispersion system of nano-chitosan and composite of nano-TiO2 and chitosan were prepared successfully. When applying the two nano-material system to B. mori silk and tussah silk fibers, the mechanical performances of the silk fibers improved, as well as thermal properties. And the aim of increasing the wrinkle-resistant performance, anti-bacteria performance and dyeing properties of B. mori silk and tussah silk fabrics were achieved. This paper offered a new for developing novel functional silk materials.