Hye Jung Youn

Lactase is commonly found in white-rot fungi and catalyses the abstraction of one electron from the phenolic hydroxyl group to polymerize or depolymerize lignin model compounds. Lactase degrades both p-1 and PO-4 dimers via C,-C, cleavage, C, oxidation and alkyl-aryl cleavage. Also, aromatic ring cleavage may be detected following the action of lactase. Lactase can also oxidize non-phenolic compounds when primary mediators, such as 2,2'-azinobis(3_ethyIbenzthiazohne-6sulfonate), are co-present.

Abstract Fold cracking of coated papers has become important because of the increase in the coat weight and the content of low cost co-binder. The effects of base paper characteristics of coated paper were investigated to reduce fold cracking. We evaluated the fold cracking of coated paper prepared with different mixing ratios and beating degrees of pulp fibers. Hardwood bleached kraft pulp (Hw-BKP) and softwood bleached kraft pulp (Sw- BKP) were used to prepare base papers for coating. The mech

Abstract Porous cellulose nanofibril (CNF) foam was prepared by stabilizing bubbles with CNF and a surfactant and then drying the stabilized wet foam in a convection oven. The consistency of carboxymethylated CNF (CMCNF) and the addition amount of the surfactant were controlled and the effects of these factors on the CNF wet foam and dry foam properties were investigated. An adequate amount of the surfactant (0.02–0.04 wt%) with CMCNF consistency higher than 0.5 wt% yielded wet foams with excell

Cellulose nanofibrils (CNFs) have been used as reinforcing elements in optically transparent composites by combination with polymer matrices. In this study, strong, optically transparent, and thick CNF/epoxy composites were prepared by immersing two or four layers of CNF sheets in epoxy resin. The morphology of the CNF, the preparation conditions of the CNF sheet, and the grammage and layer numbers of the CNF sheets were controlled. The solvent-exchanged CNF sheets resulted in the production of

Cellulose nanofibril (CNF)-added polyvinylpyrrolidone (PVP) hydrogels were prepared using different types of CNFs and their properties were investigated. CNFs with different morphology and surface charge properties were prepared through quaternization and carboxymethylation pretreatments. The quaternized CNF exhibited the narrow and uniform width, and higher viscoelastic property compared to untreated and carboxymethylated CNF. When CNF was incorporated to PVP hydrogel, gel contents of all hydro

This study focused on the nonlinear rheological characterization of three types of cellulose nanofibril (CNF) suspensions under large amplitude oscillatory shear (LAOS) flow. Three different CNFs were produced, two by mechanical fibrillation alone under different conditions [here named microfibrillated cellulose (MFC) and U-CNF] and the other by mechanical fibrillation after carboxymethylation (CM-CNF). MFC and U-CNF had broad width distributions, whereas CM-CNF had narrower fibril width and wid

Abstract Durable papers should exhibit high mechanical strength and good soiling resistance. In this study, cellulose nanofibrils (CNF) was investigated as an additive to the polyvinyl alcohol (PVA) impregnation solution to improve the durability of paper. The impregnation suspensions were prepared by adding CNF to PVA solution in various ratios, and were used to impregnate a base paper. The PVA-CNF suspensions exhibited good dispersion stability; however, the low shear viscosity increased as it