• Title, Summary, Keyword: D.S. (degree of substitution)

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Synthesis of Various Siloxylcellulose Derivatives (Siloxylcellulose 유도체의 합성)

  • Hong, Jae-Jin;Yang, Jae-Kun
    • Applied Chemistry for Engineering
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    • v.10 no.2
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    • pp.275-280
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    • 1999
  • Cellulose has three hydroxyl groups with different reactivity. By substitution reaction, trimethylsiloxyl-, vinyldimethylsiloxyl-, allyldimethylsiloxyl-, phenyldimethylsiloxyl-, 3,3,3-trifluoropropyldimethylsiloxyl- and tris(trimethylsiloxy)siloxylcellulose were synthesized IR, NMR, and elemental analysis were used for confirming their structures, degree of substitution (D.S.) and the reactivity of siloxylation agent, respectively. The D.S. values were 2.5, 2.2, 2.1, 2.2, 2.6, 0.7 for the corresponding siloxylcellulose.

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Total Utilization of Woody Biomass by Steam Explosion(II) -The Preparation of Carboxymethylcellulose from Exploded Wood- (폭쇄법(爆碎法)을 이용(利用)한 목질계(木質系) biomass의 종합적(綜合的) 이용(利用)(II) -폭쇄재(爆碎材)로부터 Carboxymethyl cellulose의 제조(製造)-)

  • Han, Sang-Yeol;Chang, Jun-Pok;Lee, Jong-Yoon
    • Journal of the Korean Wood Science and Technology
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    • v.22 no.2
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    • pp.30-36
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    • 1994
  • Steam explosion process is one of the most efficient, pretreatment method for the utilization of lignocellulosic biomass. The carbxymethyl-cellulose(CMC) was prepared with steam exploded wood(EXW), pine(Pinus densiflora) and oak(Quercus mongolica), by standard method using isopropyl alcohol and monochloroacetic acid. The range of water solubility of carboxymethylated pine exploded wood was 45.2~66.8 % and those of oak was 60.7~84.7 %. The degree of substitution(D.S) of carboxymethylated pine exploded wood was 0.11~0.33 and oak exploded wood was 0.48~0.76. The color of carboxymethylated pine and oak exploded wood was brown-black. When carboxymethylated EXW was purified by sulfuric acid, the yield of carboxymethylated wood was lower than non-treated one. However, the color was still brown-black although after delignification. In carboxymethylated EXM prepared after delignification, the water solubility and degree of substitution(D.S) of pine were 81.4~95.9 % and 0.71~0.79, and those of oak were 76.2~89.5 % and 0.79~1.05. The values were higher than non-treated. The degree of substitution of purified carboxymethylated wood prepared with delignified EXM, pine and oak were 0.50~0.71 and 0.70~0.88. The color of carboxymethylated wood was white. In carboxymethylated wood preparde after delignification of EXM, swelling ratio and water retention value of pine were 95.9~96.5 and 580.0~751.2, those of oak were 76.2~89.5 and 124.3~307.6.

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Total Utilization of Woody Biomass by Steam Explosion (III) - The Preparation of Acetate from Pine and Oak Exploded Wood - (폭쇄법을 이용한 목질계 바이오매스의 종합적 이용 (III) - 소나무와 신갈나무 폭쇄재로부터 셀룰로오스 아세테이트의 제조 -)

  • Lee, Jong-Yoon;Chang, Jun-Pok;Yang, Jae-Kyung
    • Journal of the Korean Wood Science and Technology
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    • v.23 no.2
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    • pp.26-31
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    • 1995
  • Acetylcellulose(AC) was prepared with steam exploded wood(EXW) and EXW after delignification with sodium chlorite, pine (Pinus densiflora) and oak (Quercus mongolica) woods. The color of acetylated pine and oak exploded wood was brown, degree of substitution(D.S) of pine was 1.47~2.09, and this of oak was 1.49~2.29. The hemicellulose content of acetylated pine and oak exploded wood was 0~3.4% and 1.49~11.3%, individually. The degree of substitution of acetylated wood prepared from delignified EXW in the pine and oak wood was 0.50~0.71 and 0.70~0.88, individually. Hemicellulose content of acetylated EXW with sodium chlorite after delignification in the pine and oak wood was less than 1% and 0.6~2.5%. The color of acetylated wood after delignification was white. IR-spectra of acetylated pine and oak EXW after delignification were found that peaks at around 1740$cm^{-1}$ and 1200$cm^{-1}$ increase markedly, due to ester carbonyl group.

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A Study on the Water-soluble Fiber at the Room Temperature using Carboxymethylcellulose(CMC) Synthesis (Carboxymethylcellulose 제조공정을 이용한 상온에서의 수용성 섬유에 관한 연구)

  • Song, Ho-Jun;Choi, Youngmin;Park, Jin-Won
    • Clean Technology
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    • v.11 no.2
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    • pp.105-116
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    • 2005
  • Carboxymethylcellulose(CMC) which is water soluble at room temperature was manufactured from the cellulose material in this study. Experimental parameters were reaction temperature, time and concentration of NaOH and monochloroacetic acid. CMC was tested for solubility, degree of substitution(D.S.) and tensile strength. The surface structure of CMC fiber was tested using scanning electron microscope(SEM). CMC manufactured from viscose rayon was affected by the chemical concentration rather then the reaction time and temperature. Also, degree of substitution is closely related to the solubility of the CMC.

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Preparation of Cellulose Graft Copolymers as Super Water Absorbents(I)-Graft Copolymerization of Acrylamide onto Low Cyanoethylated Wood Pulp- (고흡수성 재료로서 셀룰로오스계 그라프트 고분자의 제조(I) - 저치환 시아노에틸화 목재 펄프와 아크릴아미드의 공중합 -)

  • 문성필;김재필
    • Textile Science and Engineering
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    • v.33 no.8
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    • pp.715-721
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    • 1996
  • Super water absorbents were prepared by graft copolymerization of acrylamide(AM) monomer onto the low cyanoethylated wood pulp(LCE-WP) having degree of substitution(D.S.) 0.13, 0.35 and 0.63 followed by alkaline hydrolysis. The copolymerization rate of AM onto the LCE-WP of D.S. 0.13 and D.S. 0.35 were similar, while the LCE-WP of D.S. 0.63 showed faster copolymerization rate than the other two LCE-WPs. The degree of hydrolysis of super water absorbents was in the range of 60-85%. H-LCE-WP-g-PAM obtained by alkaline hydrolysis of the grafted LCE-WPs showed higher absorbency than that of WP. The H-LCE-WP-g-PAM prepared from the LCE-WP of D.S. 0.35 having graft yield of 290% exhibited the largest absorbencies of 5400 g/g for water and 75 g/g for 0.9% NaCl solution, respectively. Their absorbencies were about twice as much as those of the super water absorbent from WP.

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The Separation, Purification and Utilization of Wood Main Components by Steam Explosion in Low Pressure (II) - Characterization and Utilization of Separated Wood Polysaccharides - (저압(低壓) 폭쇄처리(爆碎處理)에 의한 목재주성분(木材主成分)의 분리(分離)·정제(精製) 및 이용(利用) (II) - 탄수화물(炭水化物)의 화학적(化學的) 성상(性狀)및 이용(利用) -)

  • Eom, Chan-Ho;Eom, Tae-Jin;Lee, Jong-Yoon
    • Journal of the Korean Wood Science and Technology
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    • v.24 no.2
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    • pp.20-25
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    • 1996
  • Wood chips of oak(Quercus mongolica) and larch(Larix leptolepis) were exploded with the optimum condition. Main components of exploded wood were separated with hot hot water and methanol. The hemicelluloses were purified from hot water extracts and alditol complexs were prepared from purified hemicellulose. And also, cellulose nitrate was prepared from extractive residue and characterized. The results can be summarized as follows. 1. Amounts of carbohydrate(72~79%) in the crude hemicellulose of larch wood was more than those of oak wood(55~66%). 2. The crude hemicelluloses were mainly composed of oligosaccharides in oak wood but those in larch wood contained about 50% monosaccharides. 3. Decolorization of hemicellulose was successful with activated charcoal and ion-exchange resin treatment. The alditol yields were 56.3~82.9%. 4. The degree of substitution(D.S.) of cellulose nitrate was 1.95~2.87 and it showed a good acetone solubility.

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Synthesis of CM-Chitin from Crab Shells (게껍질로부터 CM-Chitin의 합성)

  • Ahn, C.I.;Kim, S.H.;Yoo, Y.J.;Park, C.H.;Lim, H.S.;Park, C.K.;Park, E.K.
    • Journal of the Korean Applied Science and Technology
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    • v.10 no.2
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    • pp.41-47
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    • 1993
  • Chitin was isolated from crab shells by modified Hackman's method, which was treated again with aqueous sodium hydroxide solution to give alkali chitin(sodium alkoxide of chitin). And after, the alkali chitin is allowed to react with monochloroacetic acid to synthesize 6-O-(carboxymethyl) chitin [CM-Chitin] under diminished pressure. In order to synthesize high performance CM-Chitin as hygroscopic agent, it was measured that the yield and degree of subsititution of each CM-Chitin according to molar ratio(monochloroacetic acid equivalent mol/N-acetyl-D-glucosamine residue) and their moisture-absorption and moisture-release properties were measured and compared with those of hyaluronic acid. The moisture-absorption and moisture-release properties of CM-Chitin, especially 0.8 in degree of substitution, were found quite similar to those of hyaluronic acid. The preliminary results show that CM-Chitin might be used as hygroscopic agent instead of hyaluronic acid in field of cosmetics.

The Synthesis of Sodium Starch Sulfate and Its Application (Sodium Starch Sulfate의 합성과 그의 응용(I))

  • 이시호;고석원
    • Textile Science and Engineering
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    • v.20 no.4
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    • pp.1-8
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    • 1983
  • Starch sulfate was synthesized as sodium salt by reacting DMF-So$_3$complex with starch nitrite which had been obtained by substituting the hydroxyl groups of starch to nitrite groups by treating starch with dinitrogen tetroxide in N,N-dimethylformamide (DMF) medium. In the process of synthesizing the starch sulfate, the optimum condition was obtained by measuring the sulfur content and the degree of substitution (D.S.) at the various conditions of suspending time in DMF, nitrosation temperature, sulfation time and sulfation temperature. In the sulfation, the reasction order, reaction rate constant and activation energy from Arrhenius plot were also investigated. Sodium starch sulfate was reacted with amine compound, e.g. ethylenediamine, in the presence of acid and the resulting product was identified by IR spectral analysis. On the other hand, sodium starch sulfate was reacted with the crosslinking agent, e.g. DMDHEU, in the presence of NH$_4$Cl catalyst and the resulting product was identified by IR spectral analysis.

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Physicochemical Properties of Oxidized Waxy Maize Starches with Sodium Hypochlorite (찰옥수수 산화전분의 이화학적 특성)

  • Chung, Man-Gon;Jeon, Young-Seung;Lee, Sur-Koo;Park, Jong-Moon;Lim, Bun-Sam
    • Korean Journal of Food Science and Technology
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    • v.30 no.1
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    • pp.42-48
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    • 1998
  • Physicochemical properties of waxy maize starch and oxidized waxy maize starch with sodium hypochlorite $(0{\sim}60\;mg\;CL_2/g\;starch,40^{\circ}C,\;pH\;10,\;3.0\;hr)$ were studied. As sodium hypochlorite concentration was increased, the content of crude lipid and crude protein of the oxidized starch were decreased. And crude protein content and whiteness was considered to show negative regression. However, the crude ash content of the oxidized starch increased significantly with oxidation and bore a positive regression to the chlorine content. There was a progressive increase in the carboxyl content with increasing oxidant level. After pasting in hot water and cooling, viscosity of the oxidized starches were drastically lower than that of native starch . As carboxyl contents of the oxidized starch increased, the solubility and swelling power was increased. When waxy maize starch treated with 0, 1.5, 3.0 and 6.0% sodium hypochlorite, temperature of initial gelatinization of oxidized starch was shown to 65, 65, 60 and $50^{\circ}C$, respectively. The oxidized waxy maize starches also form clearer pastes. Water binding capacity of the oxidized starch decreased as the degree of carboxyl group substitution increased. Waxy maize starch has polygonal and some round granules which range from about 3.7 to $20\;{\mu}m$ in diameter. Surface appearance of the waxy maize starch became rough when oxidized with sodium hypochlorite. When homogenate of the oxidized waxy maize starch solution and corn germ oil was stored under room temperature for 24 hours, the emulsion stability was considered to depend on starch concentration and degree of substitution.

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Electronic Properties and Conformation Analysis of π-Conjugated Distyryl Benzene Derivaties

  • Kim, Cheol-Ju
    • Bulletin of the Korean Chemical Society
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    • v.23 no.2
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    • pp.330-336
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    • 2002
  • A quantum-chemical investigation on the conformations and electronic properties of bis[2-{2-methoxy-4,6-di(t-butyl)phenyl}ethenyl]benzenes (MBPBs) as building block for ${\pi}$-conjugate polymer are performed in order to display the effects of t-butyl and methoxy group substitution and of kink(ortho and meta) linkage. The conjugation length of the polymers can be controlled by substituents and kink linkages of backbone. Structures for the molecules, o-, m-, and p-MBPBs as well as unsubstituted o-, m-, and p-DSBs were fully optimized by using semiempirical AM1, PM3 methods, and ab initio HF method with 3-21G(d) basis set. The potential energy curves with respect to the change of single torsion angle are obtained by using semiempirical methods and ab initio HF/3-21G(d) basis set. The curves are similar shape in the molecules with respect to the position of vinylene groups. It is shown that the conformations of the molecules are compromised between the steric repulsion interaction and the degree of the conjugation. Electronic properties of the molecules were obtained by applying the optimized structures and geometries to the ZINDO/S method. ZINDO/S analysis performed on the geometries obtained by AM1 method and HF/3-21G(d) level is reported. The absorption wavelength on the geometries obtained by AM1 method is much longer than that by HF/3-21G(d) level. The absorption wavelength of MBPBs are red shifted with comparison to that of corresponding DSBs in the same torsion angle because of electron donating substituents. The absorption wavelength of isomers with kink(orth and meta) linkage is shorter than that of para linkage.