Study On The Micro-structure Changes Of Hei Longjinag’s Hemp Fibers In The Enzyme Treatment Process

Hemp fiber as a kind of green natural textile raw material, People pay more and more attentions on it. Because hemp fibers have several desirable properties, and it accords with the request of the environmental protect and the principle of national textile industry. Degumming treatment is pre-treatment process should be carried out in all the fibers,our country currently degumming of hemp fiber is still the traditional chemical method,This method has the following drawbacks:removal of lignin is not ideal,Process is longer,Number of raw materials and energy is consumed,fibers are serious injuries and so on.Based on the above questions, this paper developed a series of research work, it expect to supply theoretical guidance to the development and application of hemp fiber.The main woke of this paper were:Hemp fiber pretreated with acid pectinase and xylanase was degummed, only use enzymatic method can not be completed for degumming of hemp fiber is determined,Therefore, the traditional method for sodium hydroxide hemp fiber was taken in second degumming,and compare with traditional chemical method to do a detailed research.During the discussion of the process,By comparison of the fiber surface and micro-structure between two degumming,Derived advantages and disadvantages of the two methods, and propose ways to improve.Through single factor experiments and orthogonal test to determine the optimum technological conditions for degumming,namely the amount of pectinase is 9%(owf), xylanase dosage is 12%(owf), the time is 120 min,the temperature is 55℃,pH is 4.6 and the concentration of sodium hydroxide in second degumming is 6.0g/L. The fracture strength, whiteness, residue rate of hemp was make comparisons between the joint degumming and the traditional chemical method.The degumming experimental results showed that Enzymatic degumming of single process can remove pectin layer, pectin, hemicellulose,lignin fibers of lower degree of surface coverage, but on the interior of hemp fiber pectin, lignin removal limited;sodium hydroxide can be single process of hemp fiber degumming,but through the scanning electron microscope we can see that this method is relatively large damage to fiber;the combined method is better than the above two kinds of single process,the damage degree of the surface of the fiber is small,residual impurities is less,effectively reduce the use amount of sodium hydroxide,meet the requirements of the green textile.The treated hemp fiber by hydrogen peroxide with single factor and orthogonal test to determine the optimal bleaching process conditions were as follows: the temperature of 90℃, the concentration of H2O2 is 9g/L, the processing time for 80 min.Structure of cellulose structure and the crystalline region of pretreatment process of hemp fiber degumming and bleaching in in no essential changes and the crystal type basically unchanged.The bleached samples by infrared spectrum analysis shows the generation of hydrogen peroxide oxidation of a wide range of hemp fiber, not only can destroy a large number of double bond structure, but also destroy the pigment color group and lignin in the chromophore can produce bleaching. Observation and analysis of the bleached fibers will not appear obvious damage of crystal region by XRD diffraction spectrum and scanning electron microscope picture contrast of bleached fiber and hemp fiber degumming and fiber, can maintain the original physical performance.