壳聚糖与阳离子淀粉接枝共聚物作为造纸助剂的研究

Copolymers of Chitosan and Cationic Starch as Paper Additives

研究了壳聚糖和阳离子淀粉接技共聚反应。共聚物作为造纸增强剂加入浆中，其应用效果在用量相同时，增强效果优于复配物，达到相同的使用效果时，用量少于复配物。共聚物在纤维间产生了离子键结合，增加形成氢键的能力，是提高纸页强度的主要机理。

Graft-copolymerization of cationic starch and chitosan and the strength enhancing mechanisms of the resulted copolymer when added to a furnish of eulaliopsis binata (Retz) hubbard and wheat straw pulp are investigated in this paper. It is found that cationic starch cross-links with chitosan in the presence of an acidic media. The copolymer exhibits better strenghening effects than when as individuals and not copolymerized , chitosan and catonic starch are added together to the furnish, it is also showed that the optimum addition level of the c-c additive is 1.0% and it is effective at pH 5. 0. Witn increasing molecular weight of chitosan,the c-c additive becomes less effective. It is apparent that c-c additive promotes fiber to fiber bonding as well as bondcd area , leading to better paper strenght, without any influence in the original fiber strength. Besides ,it is found that c-c additive can promote the formation of hydrogen bonds, it can also create new bonding sites on the fiber surface, which are different from conventional hydrogen bond. These new bonds are not the only factor that improves the fiber bonding strength. IR studies reveal that covalent bond are non-existent between the c-c additives and the fibers, rather a large number of hydrogen bonds are being developed at the-OH and NH2 groups on the fiber surfaces. The additive tends to form ionic bonds from the fact that the c-c additive improves the wet tesile strength of the paper more significantly when there are more carboxylic groups in the pulp.