A Study Of The Extraction, Dissolution And The Film-forming Properties From The Herb Cellulose

Cellulose is one of the most abundant natural polymer materials on earth, which has excellent performance and widely applications because of its renewable. The traditional processes of cellulose solution are being replaced step by step, as a result of the seriously environmental problems. The newly solution systems not only dissolve cellulose well, but also pollute merely, recovery easily. However, only NMMO system has attracted the most attention, which could dissolve cellulose directly. Except for preparing Lyocell fiber, with strong permeability and hygroscopicity, the process would be used for the biodegradable membrane preparation. Not only the mechanical property of the membrane is well, be the micro pore of the membrane can controlled easily.The raw materials in the process are mainly from the renewable trees; however, they are not too much in China. So that, the herb is choose to be the raw material, due to the abundant product and under-utilization. In this work, we studied the extraction and dissolution of the cellulose, the performance of cellulose membrane:Firstly, the component and the polymerization degree of the triangle yellow grass, reed, water grasses and straw are used to analyze by cuprammonium method. According to the experiment, the biggest cellulose content and the highest polymerization degree all from the triangle yellow grass among the several samples. In view of the effect between the degree and the appliance, triangle yellow grass was chose to study, lastly. Secondly, the alkali scouring method was used to extract cellulose from the herb, and the suitable condition maybe the concentration is 13 %, and the time is 3h. At the same time, phosphoric acid acidification-Fenton oxidation technology is employed to treat the straw black liquor initially. As a result, the CODcr could be decreased largely, about 95 %, and the removal rate of the chromaticity is great. Furthermore, the lignin and phosphatic by-products could be gotten, which have higher added-value.Finally, the cellulose was successfully dissolved and used to prepared uniform membrane with the NMMO/H2O solvent system. As the concentration of the cellulose growing, the viscosity of the solution was increasing, while it was decreasing with the increasing of the temperature. The additives, which are ammonium chloride and DMSO, make the viscosity of the solution reduce significantly. Further more, the effect of the DMSO is more remarkable.The effect of the reaction condition on the mechanical property, including concentration, solution temperature, the concentration and temperature of the coagulating bath, were studied by the single factor experiment and orthogonal experiment. The results are as follows: cellulose concentration is 9 %; the dissolution temperature is 105℃; the coagulation bath, deionized water, is 20℃. With the additive, such as ammonium chloride, DMSO and nano-silica, the mechanical property of the membrane was improved much more, especially the modified nano-silica.