| With the improvement of people’s living standard,price is one of the considerations for tissue paper products,the softness of tissue paper has become more and more important factor to purchase the tissue products.The paper industry needs the green and environment friendly technologies.This thesis focused on the use of ultrasonication assisted cellulase treatment to improve the softnesss of the bamboo fiber and tissue paper.Firstly,cellulase can improve the softness of fibers.The softness and water retention value of single fiber increased with increasing of cellulase dosage.When the amount of cellulase is 0.30 EGU/g,the softness of single fiber of high-yield pulp fiber increased from 2.52×1014/(N·m2)to 22.34×1014/(N·m2).The softness of single fiber of kraft pulp increased from 5.47×1014/(N·m2)to 30.44×1014/(N·m2).The softness of single fiber of kraft pulp is basically close to the commercial tissue paper fibers,and the softness of high yield pulp greatly improved.However,the higher amount of cellulase was needed when the higher softness level was required.Secondly,the use of ultrasonication treatment of fiber can destroy the primary wall and secondary wall S1 layer of the fiber.It can expose the S2 layer of micro fiber and open the fiber structure.It also can promote the fiber water absorption and swelling and improve the softness and water retention value.In this thesis,it was determined that the optimal conditions for ultrasonication treatment to improve fiber softness were pulp concentration of 0.5%,ultrasonic power of 700 W,and treatment time of 40 min.The softness of single fiber can reach 29.54×1014/(N·m2)and 16.58×1014/(N·m2)for high-yield bamboo pulp fiber and kraft pulp fiber,respectively,after the ultrasonication treatment.Ultrasonication treatment can effectively promote the degradation of cellulase of the fibers to help the cellulase penetrate the fiber structure,which led the more pronounced effect on the fiber softness.The optimal ultrasonication treatment condition was 0.06 EGU/g cellulase dosage,the softness of single fiber was 32.01×1014/(N·m2)and 21.61×1014/(N·m2)for high-yield pulp and kraft pulp by ultrasonication assisted cellulase treatment.The handsheets of the above treatments were made on a handsheet machine.For kraft pulp fibers,when the cellulase dosage was 0.06 EGU/g,a high softness of 69.4 could be achieved when the cellulase dosage was 0.06 EGU/g after 40 min of ultrasonication treatment.For high-yield bamboo pulp,when the cellulase dosage was 0.06 EGU/g,a high softness of 67.20 could be achieved after 10 min of ultrasonication treatment.After 40 min of ultrasonication treatment and 0.06 EGU/g cellulase treatment,the bulk of the handsheets of the kraft pulp decreased by 0.16 cm3/g,and bulk of the handsheets of the high-yield pulp decreased by 0.86 cm3/g.When the high-yield bamboo pulp was treated with ultrasonication treatment for 10 min and cellulase of 0.06 EGU/g,the tensile index of the handsheets increased by 0.18 kN/m,while the tensile index of the handsheets of kraft pulp was basically unchanged.Based on the analysis of the fiber dynamics model,the ultrasonic wave is likely to break the cellulose chain structure of the sigma phase.The ultrasonication treatment made the cellulase contact with the fiber more fully and obtain more attachment sites.It also caused hydrogen bond destruction and reduced the crystallinity.XRD,NMR and FT-IR analysis results confirmed that ultrasonication destroied the crystal structure of cellulose fiber and decreased fiber crystallinity.The fluted ultrasonic processor has the characteristics of large processing capacity and controllable variables,which provides the possibility for the industrial application of cellulase combined with ultrasonication processing technology.Ultrasonication assisted cellulase treatment can realize green production and have certain economic feasibility.In the face of many difficulties,the industrialization of this technology needs the joint efforts of researchers and instrument manufacturers. |
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