• Korean Journal of Materials Research
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• v.28 no.4
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• pp.227-234
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• 2018

We investigate the effect of the modification of cellulose acetate propionate as an organic vehicle for silver paste on solar cell efficiency. For the modification of cellulose acetate propionate, poly(ethylene glycol) is introduced to the hydroxyl groups of a cellulose acetate propionate backbone via esterification reaction. The chemical structure and composition of poly(ethylene glycol) functionalized cellulose acetate propionate is characterized by Attenuated total reflectance Fourier transform infrared, $^1H$ nuclear magnetic resonance, differential scanning calorimetry and thermogravimetric analysis. Due to the effect of structural change for poly(ethylene glycol) functionalized cellulose acetate propionate on the viscosity of silver paste, the solar cell efficiency increases from 18.524 % to 18.652 %. In addition, when ethylene carbonate, which has a structure similar to poly(ethylene glycol), is introduced to cellulose acetate propionate via ring opening polymerization, we find that the efficiency of the solar cell increases from 18.524 % to 18.622 %.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.977-982
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• 2013

Cellulose mixed esters (CME), substituted by various fatty acyl chains, are renewable bio-based polyesters. It has lots of potential due to the biodegradable property. In this study, Alpha cellulose was activated for 2h at $40^{\circ}C$ in deionized water prior to synthesis. Homogeneous esterification of CME was accomplished with water-activated alpha cellulose, various saturated fatty acids and acetic anhydride in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) medium. CME was obtained after 5 hr at $120^{\circ}C$. The filtrated products were characterized using TGA, FT-IR, 1H-NMR and FE-SEM, and the influence of water activation on the total degree of substitution was investigated.

• Journal of the Korean Wood Science and Technology
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• v.25 no.1
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• pp.56-64
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• 1997

Since there are three hydroxyl groups on each anhydroglucose ring of the cellulose, the renewable resources, we can get various functional papers by the chemical modification of cellulose. The reaction involving the introduction of the ${\beta}$-cyanoethyl ($-CH_2-CH_2$-CN) group into organic substances containing reactive hydrogen atoms is known as cyanoethylation. Cellulose reacts with acrylonitrile in the presence of strong alkalis in a typical manner of primary and secondary alcohols to form cyanoethyl ethers. In cyanoethylation, important factors of reaction are temperature, concentration of the NaOH, and addition rate of acrylronitrile. FT-IR spectra of cyanoethyl group was confirmed at $2250cm^{-1}$, which corresponds the introduction of aliphatic nitrile group. Effect of cyanoethyl DS(degree of substitution) on strength properties was resulted that cyanoethylated BKP of DS 0.04 appeared to be the best choice for overall strength properties. Also, excellent thermal stability in aging characteristics was obtained.

• Polymer(Korea)
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• v.31 no.5
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• pp.436-441
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• 2007

In this work, the multiwalled carbon nanotubes(MWNTs) were functionalized with sodium dodecylbenzene sulfonate(SDBS) and then MWNTs/Lyocell composite fibers were prepared. The properties of MWNTs, the functionlization on the surface of MWNTs and their dispersion in the cellulose matrix were characterized by TEM, SEM, WAXD and FT-IR. The results showed that SDBS has been coated successfully onto the surface of the MWNTs by functionlization. This can improve effectively the dispersion uniformity of MWNTs in NMMO aqueous solution and is helpful to prepare a spinnable spinning dope. Moreover, the resultant MWNTs/Lyocell composite fibers still have cellulose II crystal structure, and their tensile strength and initial modulus increased with the increasing draw ratio and reached the optimal value with adding 1 wt% MWNTs. The thermal stability of the composite fiber was also improved by the addition of the MWNTs.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.60-67
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• 2017

In this study, we performed surface modification of biodegradable microcrystalline cellulose (MCC) to use as a filler in polyethylene (PE) composite in food packaging application. We modified MCC surface with (3-trimethoxysilylpropyl)diethylenetriamine (TPDT) silane coupling agent, which has one primary amino group and two secondary amino groups per molecule, to introduce amino groups with a carbon dioxide adsorption capability in MCC. Effects of each of the reaction conditions such as amount of TPDT introduced, swelling time, reaction temperature, and reaction time on surface modification degree of MCC were investigated by changing a variety of above reaction conditions. The amount of TPDT grafted on MCC surface and formation of chemical bonds were confirmed by Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and solid state $^{29}Si$ nuclear magnetic resonance (NMR) spectroscopy. We confirmed increase of grafted amount of TPDT on MCC with increasing reaction time, reaction temperature, and amount of introduced TPDT.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1545-1548
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• 2014

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.1-8
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• 2005

Bacterial cellulose (BC), which is produced by some bacteria, has unique structural, functional, physical and chemical properties. Thus, the mass production of BC for industrial application has recently attracted considerable attention. To enhance BC production, two aspects have been considered, namely, the engineering and genetic viewpoints. The former includes the reactor design, nutrient selection, process control and optimization; and the latter the cloning of the BC synthesis gene, and the genetic modification of the speculated genes for higher BC production. In this review, recent advances in BC production from the two viewpoints mentioned above are described, mainly using the bacterium Gluconacetobacter xylinus.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.3
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• pp.26-33
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• 1997

The bacterial celluloses are very different in its physical, chemical and morphological structures compared to wood cellulose. These fibers have many unique properties that are potentially and commercially beneficial. This study was aimed to elucidate the production of bacterial celluloses and to improve their physical properties by chemical pretreatment. Bacterial celluloses produced by static culture had gel-like pellicle structure. The pellicle thickness was increased with the increasing time, and its layer was about 1.8cm after one-month incubation. The pellicles extruded from the cells of Acetobacter had a non-crystalline structure during initial growing stages, gradually getting crystaliyzed with the incubation time elapse, and eventually fumed to the cellulose I crystals. Young＇s modulus of bacterial cellulose sheet was increased with increasing NaOH concentration, and resulted in the highest at 5% NaOH concentration. Similar results with NaClO3 pretreatment can be observed. Too concentrated alkali solutions induced the destruction of cellulose fibrils and changed the mechanical properties of the sheets. These alkaline pretreatment have removed non-cellulosic components(NCC) from the bacterial cellulose, and enhanced inter-abrillar bonding by direct close contact among cellulosic fibrils.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.5
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• pp.20-25
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• 2007

Henequen fibers were treated by electron beam irradiation and by NaOH to make surface modification for better bonding in the manufacture of biocomposite. Impurity removal and carbonyl group formation were noticed in the previous study by electron beam irradiation, but extensive cellulose degradation were also noticed. To evaluate the effects of electron beam irradiation on cellulosic fibers further, henequen fibers, cotton pulp, cotton fibers, and cellophane were irradiated by electron beam, and their changes of cellulose viscosity, chemical composition, and tensile strength were measured and analyzed.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.529-533
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• 1999

In addition to catalyzing the synthesis of dextran from sucrose as a primary reaction, dextransucrase also catalyzes the transfer of glucose from sucrose to other carbohydrates that are present or are added to the reaction digest. We have synthesized new glucans having new structures and new characteristics, by transferring D-glucose of sucrose to $\alpha$-cellulose and by using the constitutive dextransucrase obtained from Leuconostoc mesenteroides B-742CBM. The final reaction products were composed of soluble- and insoluble-glucans. The yields of soluble- and insoluble-glucans were theoretically 21% $\pm$ 2.2 and 68% $\pm$ 5.1, respectively. The remainder of the reaction products was recovered as a mixture of olgiosaccharides that could not be precipitated by 67%(v/v) ethanol. Treating the modified glucans with endo-dextranase and/or cellulase, oligosaccharides were produced that were not formed from the hydrolysis of native cellulose or B-742CBM dextran. The modification of the cellulose was confirmed by methylation and acid hydrolysis of the soluble-and insoluble-glucan. Both (1->4) and(1->6) glycosidic linkages were found in both of the glucans.