Effects Of Endo-glucanase Pretreatment On Prepare Nanofibers By TEMPO-Mediated-Oxidation

Cellulose is one of the most abundant natural polymer materials, while the preparation of nano cellulose fiber(NFC) has become a growing concern in this world, which has attracted great attention in recent years. NFC is mainly obtained from wood, cotton, stalks through mechanical, chemical, biological and synthetic method. It has many features, such as high crystallinity, large specific surface area, high purity and young’s modulus, good biodegradable property and compatibility, so it can be applied in the area of biological pharmacy, food processing, functional materials and papermaking. However, the existing preparation methods of NFC have many defects, like low product yield, high demand of facility and energy consumption, complex process and unreasonable particle size and size distribution of NFC. Therefore, the study of NFC preparation still needs to be continued.In this paper, the fully bleached softwood pulp is pretreated by EG1, and then NFC is prepared through TEMPO oxidation with ultrasonic. During the research, the residual active chlorine and carboxyl group content of fiber can be monitored by redox and conductivity titration during TEMPO oxidation process. The flow property、size distribution and fiber morphology can be characterized by fiber particle size analyzer, capillary viscometer and transmission electron microscopy(TEM). By comparing the impact of EG1 pretreatment on NFC preparation through TEMPO oxidation with ultrasonic, the results were as follows:1.Pretreatment of EG1 increased carboxyl group content of cellulose by TEMPO catalytic oxidation with synergy of ultrasonic could be observed. Carboxyl group content was 2.05mmol/g after cellulose oxidized by ultrasonic assisted TEMPO. Cellulose was pretreated 12 h, 24 h, and 48 h respectively, then at the same oxidation condition, carboxyl group content of cellulose was 2.35mmol/g, 3.03mmol/g, 3.13mmol/g. With EG1 pretreated, transparency increased, width decreased, and time of flowed through the capillary viscometer increased were found.2.NaoH swelled or pulped nanofiber treated by EG1 could be found that carboxyl group content, transparency, and time of flowed through the capillary viscometer increased. Size distribution transferred to small direction.3.Increased treatment time of EG1, fiber yield would decrease, but at the same time yield could be kept over 93%. Fiber degree of polymerization would decline with fiber pretreated by EG1. Fiber degree of polymerization were 1478, 986, 952, 948 respectively after fiber were treated 0, 24 h, 36 h, 48 h by EG1.4.High pressure homogenize could prepare nanofiber with pretreated 24 h or 48 by cellulose, and fiber shape appeared short rod-like.