• Magazine of the Korea Concrete Institute
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• v.8 no.5
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• pp.163-170
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• 1996

Cellulose fibers, being fairly strong and stiff as well as cheap and plentiful with low energy demand during manufacture, are strong contenders for the reinforcement of cement-based materials. Cellulose fiber-cement composites, generally manufactured by slurry-dewatering procedure, can find applications in the production of flat and corrugated cement sheets and many other thin-sheet cement products. This paper presents the results of an experimental study concerned with the effects of fiber content and moisture conditions on the flexural performance of these composites. An effort was also made to study the effect of pozzolanic admixtures on the flexural performance in different moisture conditions. The test results obtained were analyzed statistically using the analysis of variance in order to derive reliable conclusions. The results generated in this study were indicative of significant effects of fiber content and moisture condition of flexural performance. There is a tendency in flexural strength to increase in increase in fiber content up to 8%: flexural toughness values continue to increase even at higher fiber contents. Moisture content has a significant effect on the flexural performance. There is a tendency in flexural strength to decrease and flexural toughness to increase with increasing moisture content Composites incorporating pozzolans showed an increase in the flexural strength while slightly reducing the flexural toughness and were sensitive to variations in moisture content.

• Clean Technology
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• v.16 no.1
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• pp.19-25
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• 2010

In this work, the conversion of crystalline cellulose into polyols in the presence of hydrogen was examined over noble metal (Pt, Ru, Ir, Rh, and Pd) catalysts supported on activated carbon. For comparison, Pt/${\gamma}-Al_2O_3$ and Pt/H-mordenite were also investigated. Several techniques: $N_2$ physisorption, X-ray diffraction(XRD), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction with $H_2$ ($H_2$-TPR) and CO chemisorption were employed to characterize the catalysts. The cellulose conversion was not strongly dependent on the types of the catalyst used. Pt/AC showed the highest yields to polyols among activated carbon-supported noble metal catalysts, viz. Pt/AC, Ru/AC, Ir/AC, Rh/AC and Pd/AC.

• Textile Coloration and Finishing
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• v.2 no.1
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• pp.31-36
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• 1990

The electrically conducting cellulose acetate/polypyrrole composite films were synthesized by exposing cellulose acetate film containing oxidizing agent to pyrrole vapour and the formation of polypyrrole is confirmed by IR and electron microscopic studies. The morphologies of polypyrrole in the composites are different depending on the oxidizing agent. Ferric chloride is most effective among several metallic chlorides to synthesize the composites with high electrical conductivity. The conductivity of composite films synthesized with 50 wt.% of ferric chloride reaches upto $10^{-2}S/cm$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.905-906
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• 2010

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.435-441
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• 2012

The direct conversion of cellulose into polyols in $H_2$ was examined over Pt catalysts supported on various zeolites, viz., mordenite, Y, ferrierite, and ${\beta}$. For comparison, Pt catalysts supported on ${\gamma}-Al_2O_3$, $SiO_2-Al_2O_3$, and $SiO_2$ were also tested. The physical properties of the catalysts were probed with $N_2$ physisorption. The surface acidity was measured with temperature programmed desorption of ammonia ($NH_3$-TPD). The Pt content was quantified with inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The Pt dispersion was determined with CO chemisorptions and transmission electron microscopy (TEM). The conversion of cellulose appeared to be mainly dependent on the reaction temperature and reaction time because it depends on the concentration of $H^+$ ions reversibly formed in hot water. Pt/H-mordenite (20) showed the highest yield to polyols among the tested catalysts. Pt/H-zeolite was superior to Pt/Na-zeolite for this reaction. The polyol yield was dependent on the surface acid density and the external surface area.

• Clean Technology
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• v.20 no.2
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• pp.108-115
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• 2014

Various metal chlorides and acid catalysts in ionic liquid solvent were investigated to directly convert cellulose into 5-hydroxymethylfurfural (5-HMF). Metal chlorides containing Sn(II), Zn(II), Al(III), Fe(III), Cu(II), and Cr(III) were used and acidic ionic liquid immobilized on silica gel as an acid catalyst and commercial acid catalysts (sulfuric acid, chloric acid, Amberlyst-15,DOWEX50x8) were used for comparison studies. The acid strength and amount of acid catalysts were probed with Hammett indicator. The selectivity and yield of 5-HMF were determined with reaction temperature, reaction time and catalyst ratio. A catalyst containing $CrCl_3-6H_2O$ and $SiO_2-[ASBI]HSO_4$ showed the highest selectivity and it was found that this catalyst had higher activity than commercial solid acid catalysts such as Amberlyst-15 and DOWEX50x8. The selectivity of 5-HMF appeared to be mainly dependent on the acid strength and catalyst ratio, it was found that levulinic acid was produced from 5-HMF by rehydration.

• Journal of Institute of Convergence Technology
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• v.1 no.2
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• pp.33-36
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• 2011

Ionic liquids based on formate and hydrogen carbonate anions were synthesized for use as solvents for the effective dissolution of cellulose and the regenerated cellulose was in the native lattice.

• Clean Technology
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• v.19 no.1
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• pp.13-21
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• 2013

The hydrogenolysis of cellulose into polyols was examined over Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalysts containing different Cs fractions. The surface area and Pt dispersion of Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalysts were found to increase with Cs content. Similar polyol yields were obtained over Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalysts irrespective of their Cs content. The catalytic activity of Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ was comparable to that of Ni/W/SBA-15 and combined catalytic systems such as Pt/AC+$H_3PW_{12}O_{40}$ and Pt/AC + $Cs_{3.0}PW_{12}O_{40}$. Some polyanion species were found to leach from the Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalyst during the course of the reaction.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.6
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• pp.357-362
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• 2015

A novel $TiO_2$-Coconut Shell Powder Composite (TCSPS), prepared by the controlled sol-gel method with subsequent heat treatment, was evaluated as an innovative photocatalytic absorbent for the removal of methylene blue. Optimal preparation conditions of TCSPC were obtained by a response surface methodology and a central composite design model. As compared with the results obtained from one-factor-at-a-time experiments, the values were approximated to the nearest condition of these values and the following experimental parameters were set as the optimum : $600^{\circ}C$ calcination temperature and 20 g of coconut shell powder loading amount.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.319-323
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• 1998

Plastic shrinkage cracking is a major concern for concrete, especially for flat structures as highway pavement, slabs for parking garages, and walls. One of the methods to reduce the adverse effect of plastic shrinkage cracking is to reinforced concrete with short randomly distributed fibers. The contribution of cellulose fiber to the plastic shrinkage crack reduction potential of cement composites and its evaluation are presented in this paper. The effects of differing amounts of fibers(0.9kg/㎥, 1.3kg/㎥, 1.5kg/㎥) were studied. The results of tests of the cellulose fiber reinforced concrete were compared with plain concrete and polypropylene fiber reinforced concrete. Results indicated that cellulose fiber reinforcement showed an ability to reduce the total area and maximum crack width significantly(as compared to plain concreted to plain concrete and polypropylene fiber concrete).