Optimization Of Bamboo Fiber Pulping Process And Preparation Of Nano-fiberillated Cellulose

Nano-fibrillated cellulose(NFC)was widely used in pharmacy,papermaking and composite materials fields,due to its light weight,large specific surface area,high strength and low thermal expansion coefficient and so on.In this paper,Ktaft bamboo pulp after oxygen delignification was used as the research object,three kinds of preparation methods of NFC are introduced: which were preparation of NFC by oxidation treatment,xylanase pretreatment combining oxidation treatment to prepare NFC and oxidation treatment combined with xylanase aftertreatment to obtain NFC.The single factor experiments were designed in the process of oxidation preparation of NFC.The optimal treatment conditions were obtained by experimental,when the ozone dosage was 0.87%,the concentration of pulp was 35%,and the pH was 2.5,a better experimental results could be obtained as follows: the viscosity was 258mL/g,the kappa number was 2.8,the crystallinity was 48% and the carboxyl content was 1.26mmol/g.The crystallinity of the pulp before and after the oxidation treatment was 36.2% and 46.8% by the X-ray diffraction analysis.The pulp before and after oxidation was observed with SEM,it was found that after the ozone bleaching,the fiber was fully expanded and the degree of the division was increased,the reason for this phenomenon is that the ozone oxidation process causes the break of hydrogen bonds between the fibers.NFC was prepared by xylanase pretreatment combined with oxidation treatment,the effect of xylanase dosage on the properties of the pulp was studied,and the optimum treatment conditions were obtained,and the optimum treatment conditions were: the xylanase dosage was 1.068U/g,the xylanase temperature was 50?,and reaction time was 3h.The results were as follows:the viscosity was 732 m L/g,the crystallinity was 37.7%,the kappa number was 2.8,and the carboxyl content was 0.82mmol/g.The pretreatment of the xylanase was followed by oxidation treatment,and the pulp properties of the fibers changed significantly,the viscosity decreased to 225mL/g,the crystallinity changed into 52.4%,the kappa number was 2.1,and the carboxyl content was 1.33mmol/g.X-ray diffraction analysis and SEM analysis were carried out for the oxidation treatment and xylanase pretreatment combined with oxidation treatment of the optimum conditions,the results showed that the crystal structure of cellulose after xylanase treatment did not change significantly,but the crystallinity was improved.The pretreatment of the xylanase was followed by oxidation treatment,and the crystallinity of the treatment was significantly higher than that of the ozone treatment.After xylanase pretreatment,it was found that the fibrous structure became more loose and porous,and oxidize after the pretreatment of the xylanase,the number of pores on the surface of the fiber increased and the groove was criss-crossed,and the damage degree of the fiber was large by detection of SEM.The oxidation treatment and the xylanase pretreatment pulp were treated with the same homogeneous times to obtain a NFC solution,it was obtained by macroscopic observation that the degree of clarity of the pulp obtained after oxidation is less than that after enzymatic pretreatment.After centrifugation,the yield of NFCof the two ways was 33.2% and53.5% separately.The results of TEM showed that there were little difference between the width of two kinds of NFC,whose width both reached nanometer level,but the difference in length was obvious.Most of the length of the former NFC were about 250 nm,there were very little of the former NFC that the length was about 100 nm.But most of the latter NFC were shorter than 250 nm,and small amount of the latter NFC shorter than 100 nm.In the process of oxidation treatment combined with xylanase aftertreatment,it could be concluded that xylanase aftertreatment had little influence on the properties of the fibers by comparing properties Between the oxidation process and xylanase aftertreatment.