• Fibers and Polymers
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• v.6 no.2
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• pp.95-102
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• 2005

Sodium cellulose carbonate (CC-Na) dissolved in $8.5\;wt\%$ NaOH/ZnO (100/2-3, w/w) aqueous solution was spun into some acidic coagulant systems. Diameter of regenerated cellulose fibers obtained was in the range of $15-50\;{\mu}m$. Serrated or circular cross sectional views were obtained by controlling salt concentration or acidity in the acid/salt/water coagulant systems. Velocity ratio of take-up to spinning was controlled up to 4/1 with increasing spinning velocity from 5 to 40 m/min. Skin structure of was developed at lower acidity or higher concentration of coagulants. Fineness, tenacity and elongation of the regenerated cellulose fibers were in the range of 1.5-27 denier, 1.2-2.2 g/d, and $8-11.3\;\%$, respectively. All of CC-Na and cellulose fibers spun from CC-Na exhibited cellulose II crystalline structure. Crystallinity index was increased with increasing take-up speed.

• Polymer(Korea)
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• v.25 no.4
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• pp.545-557
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• 2001

The crosslinked films retaining cholesteric liquid-crystalline order were prepared by casting the liquid crystalline solutions of hydroxypropyl cellulose (HPC) in methanol with the two kinds of aliphatic dicarboxylic acid chlorides (succinyl chloride and suberoyl chloride). The temperature dependence on the cholesteric pitch of the crosslinked films and the swelling behavior of the films in both water and methanol were investigated. The films displayed fingerprint patterns charateristic of cholesteric liquid-crystalline phase, and their pitches, as well as HPC itself, increased with temperature. However, the pitch of all crosslinked samples was much greater than that of HPC at the same temperature and increased with increasing concentration and chain length of the crosslinker. The crosslinked samples exhibited an anisotropic swelling in both solvents. The degree of anisotropy slightly depended on the solvent and crosslinker species, but hardly on the crosslinker concentration investigated.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.4
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• pp.237-242
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• 2008

The tunic of Styela clava(SCT) consists of a proteoglycan network. Regenerated cellulose films were prepared by solution casting and coagulation of SCT in N-methylmorpholine-N-oxide(NMMO)/$H_2O$(87/13 wt%). The crystalline structure of powdered SCT was primarily that of cellulose I. The crystalline structure of SCT films exhibited a cellulose II structure, similar to that of viscose rayon. Physical characterization of SCT films and fibers revealed an intrinsic viscosity($\eta$) of 6.35 dL/g, average molecular weight($M_w$) of 423,000 g/M, and fiber density of 1.50 $g/cm^3$ with a moisture regain and water absorption of 10.20% and 365%, respectively. The results were similar to those of cellulose films regenerated from wood pulp. Films prepared with 6 wt% SCT exhibited strong tensile strength, high water absorption, and a greater degree of elongation. Scanning electron micrographs(SEM) of film cross-sections showed a layered, sponge-like structure.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.3
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• pp.106-112
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• 2011

The effects of alkaline treatment on the WRV, crystalline structure and sheet structure of softwood and hardwood bleached kraft pulp were investigated. Sodium hydroxide and sodium carbonate were used as chemicals for alkaline treatment and two levels of alkali dosage (5%, 10%) were applied respectively. Alkali treated and untreated pulp were refined to three levels (550, 450 and 350 mL CSF). WRV of the alkali treated pulps depended on the alkaline type and concentration. It was found that the crystalline structures of softwood and hardwood pulp were not changed by refining. Sodium carbonate and lower concentration of sodium hydroxide treatment did not caused any modification of cellulose crystalline structure, while higher concentration of sodium hydroxide treatment caused the partial modification of cellulose crystalline structure. Alkaline treatment of hardwood bleached kraft pulp led to the shrinkage of fiber diameter and bulky structure of sheet. Alkaline treatment of softwood bleached kraft pulp did not cause the significant change in fiber shrinkage and bulk of sheet.

• Proceedings of the Korean Fiber Society Conference
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• 1987.06b
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• pp.15-15
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• 1987

• Journal of Microbiology and Biotechnology
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• v.31 no.10
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• pp.1366-1372
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• 2021

Bacterial nanocellulose (BNC) is a biocompatible material with a lot of potential. To make BNC commercially feasible, improvements in its production and surface qualities must be made. Here, we investigated the in situ fermentation and generation of BNC by addition of different cellulosic substrates such as Avicel and carboxymethylcellulose (CMC) and using Komagataeibacter sp. SFCB22-18. The addition of cellulosic substrates improved BNC production by a maximum of about 5 times and slightly modified its structural properties. The morphological and structural properties of BNC were investigated by using Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy and X-ray diffraction. Furthermore, a type-A cellulose-binding protein derived from Clostridium thermocellum, CtCBD3, was used in a novel biological analytic approach to measure the surface crystallinity of the BNC. Because Avicel and CMC may adhere to microfibrils during BNC synthesis or crystallization, cellulose-binding protein could be a useful tool for identifying the crystalline properties of BNC with high sensitivity.

• Polymer(Korea)
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• v.34 no.3
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• pp.210-214
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• 2010

The structural development of triacetyl cellulose (TAC) was studied as a function of solution casting processing parameters such as dope concentration, evaporation temperature, annealing temperature and the addition of plasticizer. The crystalline structure was developed by the solution casting and the level of crystallinity was increased with increasing dope concentration and evaporation temperature. The crystalline structure could be enhanced by the annealing process after formation of TAC film. Introducing plasticizer resulted in decreasing melting temperature and crytallinity of TAC film due to the increase of chain mobility. It was also found that thermal stability of TAC was improved due to the rigid structure of applied plasticizer.

• Microbiology and Biotechnology Letters
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• v.8 no.1
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• pp.41-46
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• 1980

Low molecular weight endo-glucanase was partially purified from cellulase complex using Sephadex G-100 gel chromatography. Biochemical properties of the purified component was investigated. Optimum pH and temperature determined were 6.0 and 5$0^{\circ}C$, respectively. Enzymatic hydrolysis of four cellulosic substrates having varying crystallinity was evaluated. It was found that hydrolysis of amorphous region was followed by the hydrolysis of crystalline region. In order to examine the effect of adsorption of the enzyme onto the cellulosic substrates on the hydrolysis kinetics, adsorption studies were carried out. Time course of adsorption of low molecular weight endo-glucanase onto various cellulostances was observed for 25 min. The rate and amount of adsorption to amorphous cellulose was greater than those to the crystalline cellulose. This result suggested that the role of endo-glucanasc was more important to the hydrolysis of amorphous cellulose than to the crystalline region of the cellulose.

• Journal of the Korean Applied Science and Technology
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• v.27 no.4
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• pp.508-514
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• 2010

Regenerated cellulose fibers were prepared from three pulps containing different degree of polymerization(DP) and $\alpha$-cellulose contents by dry-jet wet spinning technique with cellulose dope in N-methylmorpholin N-oxide (NMMO). The effect of antioxidant, n-propyl gallate (PG) on the properties of different regenerated celluloses was studied using X-ray diffraction, copper number calculation, and viscometry. The degradaqtion of regenerated cellulose from pulp containing higher DP and lower $\alpha$-cellulose content was occurred more seriously. The tensile strength and initial modulus of regenerated cellulose fiber obtained from NMMO dope with PG were higher than those of fiber obtained from NMMO dope without PG. All fibers showed the round shape cross section and typical cellulose II crystalline structure.

• Bulletin of the Korean Chemical Society
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• v.18 no.3
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• pp.300-305
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• 1997

Effect of a nonionic surfactant, Tween 20 on the adsorption and kinetic mechanism for the hydrolysis of a microcrystalline cellulose, Avicel PH 101, by endoglucanase Ⅰ (Endo Ⅰ) and exoglucanase Ⅱ (Exo Ⅱ) isolated from Trichoderma viride were studied. The Langmuir isotherm parameters, amount of maximum adsorption (Amax) and adsorption equilibrium constant (Kad) for the adsorption, were obtained in the presence and the absence of nonionic surfactant. On the addition of Tween 20, the Kad and Amax values of Exo Ⅱ were decreased, while those of Endo Ⅰ were not affected. These indicate that the adsorption affinity of Exo Ⅱ on the cellulose is weakened by nonionic surfactant, and the surfactant enhanced desorption of Exo Ⅱ from insoluble substrate. The enzymatic hydrolysis of the cellulose can be described by two parallel pseudo-first order reactions using the percentages of easily (Ca) and hardly (Cb) hydrolyzable cellulose in Avicel PH 101 and associated rate constants (ka and kb). The Ca value was increased by adding Tween 20 for all enzyme samples (Exo Ⅱ, Endo Ⅰ and their 1:1 mixture) implying that the low-ordered crystalline fraction in the cellulose may be partly dispersed by surfactant. The ka value was not affect by adding Tween 20 for all enzyme samples (Exo Ⅱ, Endo Ⅰ and their 1:1 mixture). The kb value of Exo Ⅱ was increased by adding Tween 20, while that of Endo Ⅰ was not affected. This suggests that the surfactant helps the Exo Ⅱ desorb from microcrystalline cellulose, and increase the hydrolysis rate. These results were show that the increase of hydrolysis of cellulose by the nonionic surfactant is due to both the activation of Exo Ⅱ and partial defibrillation of the cellulose.