REBUILDING OF COMPOUND MIDDLE LAMELLA AND ENHANCEMENT OF PAPERBOARD STRENGTH BY LIGNIFICATION TREATMENT
Compound middle lamella (CML) binds fibers together, rendering plants high physical strength. Therefore, repairing of CML structure in the paperboard by means of ligninficaion treatment is a promising method to improve paperboard properties, especially wet strength. In the present research, the formation of CML catalyzed by lignin peroxidase (Lip) was simulated in vitro. The possibility of co-polymerization between residual lignin in pulp and lignin precursor was investigated by the reaction between ~13C-labelled coniferin and guaicylglycerol-β-guaicyl ether catalyzed by Lip. The ~13C-NMR determination proves that the main substructures of the obtained dehydrogenation polymer (DHP) are β-O-4,β-5,β-β, β-1, coniferyl aldehyde and coniferyl alcohol. The results indicate the good reactivity of residual lignin and feasibility of CML rebuilding between pulp fibers through dehydrogenation co-polymerization. Furthermore, DHP based complexes were prepared by binding exogenous coniferin-α-~13C, glucomannan and pectin to the fibers, in the presence of Lip. The obtained CML- like complexes were analyzed by CP/MAS ~13C-NMR in combination with ~13C-tracer. The results show that pectin and glucomannan are linked to DHP by typical LCC linkages, I.e. Benzyl ether bonds, ester bonds, and a small amount of ketal bonds. The DHP mainly consists of β-O-4, β-β, β-5 and β-1 linkages. Moreover, there are also significant amount of coniferyl alcohol and coniferyl aldehyde substructures. Through the covalent bonding between DHP and polysaccharides and residual lignin of pulp fibers, the DHP-pectin- glucomannan complexes can be crosslinked with fibers. As a result, the paperboard strength is increased obviously after lignification treatment with coniferin in existence of pectin or a mixture of pectin and glucomannan. The dry and wet tensile strength of paperboard web are increased by 37.5％ and 166.3％ after treated with coniferin and pectin, or 42.1％ and 103％ after treated with coniferin , pectin and glucomannan. It is demonstrated that lignin precursor can be co-polymerized with lignin and polysaccharides in pulp fiber efficiently. The process is catalyzed by Lip in the presence of exogenous lignin precursor and polysaccharides. The rebuilt CML binds the pulp fibers and therefore enhances the paperboard strength.
compound middle lamella coniferin lignin-carbohydrate complexes paperboard strength
Yimin Xie Haitao Yang Peng Wang Fang Zhao
Research Institute of Pulp & Paper Engineering, Hubei University of Technology, Wuhan, 430068, P. R. Key Lab of Paper Science and Technology of Education Ministry, Shandong Institute of Light Industry,
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
24-29
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）