Grafting Modification Of Cellulose ATRP And Its Application In The Papermaking

In recent years, the attention for secondary fibre has grown along with the short-age of raw matericals for papermaking. A large quantity of dissolved and colloidalsubstance released from the process of pulping and bleaching can affect the papermak-ing and reduce the quality of paper. In the meantime, with the demand for the higherquality and strength paper has grown, the strength of paper has to be improved at thesame time of removing the DCS. The most important method to solve the problem is touse paper additive. Therefore, with the fossil resources depleted, the present researchhotspot is to make full use of renewable biomass resources and develop effective mul-tifunctional paper additive.The cellulose based water-soluble cationic polymer paper additive (Cell-g-DMC)was synthesized by atom transfer radical polymerization (ATRP). It was investigatedas anionic trash catcher and strength agent in the papermaking.Firstly, cellulose was modified by2-bromide butyl acyl bromine（BiBBr）in ionicliquids (1-butyl-3-methyl-imidazole chloride salt) to obtain cellulose macromolecularinitiator (Cell-BiB). The Cell-BiB was characterized by XRD, FT-IR and NMR analy-sis and the results indicated that the Cell-BiB was successfully synthesized. TheCell-g-DMC was obtained by ATRP in DMF using Cell-BiB, DMC, CuBr, andPMDETA as macroinitiator, monomer, catalyst and ligand, respectively. The structureof the Cell-g-DMC was characterized by FT-IR、13C NMR.The effects of differentpolymerization conditions of Cell-g-DMC on grafting efficiency, intrinsic viscosityand the positive charge density were studied, and the optimal conditions for the syn-thesis of Cell-g-DMC were as follows: the molar ratio of200:1:2:1, monomer concen-tration of50%, the reaction temperature of60°C, the reaction time of24h.The effects of electric charge density and dosage of Cell-g-DMC on turbidity,Zeta potential and size of waste newsprint deinked pulp were studied. The resultsshowed that Cell-g-DMC has high positive charge density. Cell-g-DMC was a kind ofhigh-efficiency anionic trash catcher that can fix anionic trash onto fibers by electros-tatic adsorption to decrease the turbidity and anionic charge of pulp. When the dosageof Cell-g-DMC was0.5%, the control for anionic trash showed the best effect. Also,Cell-g-DMC with higher positive charge density showed better effect.The effects of intrinsic viscosity, dosage, reaction time, rotate speed and pH of Cell-g-DMC on the strength of paper were studied. The results showed thatCell-g-DMC can improve the strength of paper obviously. The SEM image of the pa-per used Cell-g-DMC displayed that there was more point junction. The results alsoindicated that the strengthening effect of Cell-g-DMC was the best under the followingconditions: the intrinsic viscosity was143.94ml/g, the dosage of Cell-g-DMC was0.5%, the reaction time was5min, pH was7and the rotate speed was250rpm. Com-pared to the paper without Cell-g-DMC, the tensile index, the tearing index, the burstindex and the internal bond strength of the paper adding Cell-g-DMC increased by21.22%,17.26%,51.11%and56.33%, respectively. As strength agent, the hydroxylgroups and ammonium cations in the structure of Cell-g-DMC can militate with fiber,which can enhance bonding strength between the fibers and the strength of paper.