Study On The Alkylated Modification Of The Ramie Fiber

Ramie fiber pertains to smartweed ramie fiber, which is perennial herbage plant. Ramie fiber grows in China, which is age-old, graceful, the cultural connotation and is called "China grass". It possesses an important history status in the history of the weaving development of natural fabric. It bears the functions of the antisepsis, antibacterial, and anti-mildew and so on, and has the advantages of boorish, elegant, lightness, cool, high air pervious, antibacterial properties. It is a good kind of weaving materials, and is recognized as "the best natural fabric". Because ramie fiber is easy to plant, the output is high, the cellulose content reaches above 70%, the output of ramie fiber is higher than cotton. Moreover, the output of ramie fiber in China is especially abundant and is accounted for eighty percentages of the total yields in the world. Ramie fiber produced in China is richest in the world. With the development of the world economy, ninety percentage of the product of ramie fiber is sold out the west developed country such as European and American and so on. Consequently, it is an important significance for the development and research of the product of ramie fiber.However, ramie fiber has the high crystallinity, the high degree of orientation, and the elongation of the low rupture. It brings about the poor spinnability, the easy corrugation, the poor capability of dyeing, and the low degree of dye fastness in the process of ramie fiber. Therefore, the surface of ramie fiber was modified by chemical method, and then the benzylated ramie fiber was dyed in supercritical CO₂ (scCO₂) so as to prepare ramie fiber of the better dye performance. This paper mainly investigated the modification and dyeing of ramie fiber, the main results are given below:1. The benzylated ramie fiber was prepared with benzyl chloride and characterized by Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), scanning electro-microscopy (SEM), thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). Ramie fiber was pretreated by different methods. The effects of the amount of NaOH, cetyl trimethyl ammonium bromide (PTC), toluene, the temperature reaction, and the time reaction on the degree of substitution (DS) of benzylated ramie fiber were investigated. The optimal conditions of benzylated ramie fiber were obtained. The results show that the ramie fiber was dipped in sodium hydroxide solution for 4 h at a room temperature for preswelling, and then the alkali ramie fiber washed with the distilled water until neutral. The optimal conditions of the benzylation of ramie fiber were investigated, and a high DS of benzylated ramie fiber was obtained. The optimal conditions for preparing benzylated ramie fiber is as followings: the concentration of NaOH solution was 10mol/l, the mass ratio of toluene to benzyl chloride was 0.86, the mass ratio of PTC to benzyl chloride was 0.003, the reaction time of 6h and the reaction temperature of 125℃, the DS of 1.14 of the benzylated ramie fiber was achieved.The modified ramie fiber was dyed in supercritical CO₂, the reflectivity of the dispersed dye was measured by Uv-Vis spectroscopy, and the dye fastness (K/S) of the dispersed dye was calculated. The results showed that when the DS of benzylated ramie fiber was increased from 0.05 to 1.01, the dye fastness (K/S) was increased from 14.8 to 28, it increased nearly two times, and a better dye effect was obtained.2. The ethylated and butylated of ramie fiber were prepared and characterized by the infrared spectrum (FT-IR) and X-ray diffraction analysis (XRD).