• 펄프종이기술
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• 제44권4호
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• pp.43-50
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• 2012

The crystallinity index is an important characteristic of cellulose. The crystallinity value is different depending on the adopted instrument. In this study, we determined a crystallinity index of cotton and wood celluloses using wide-angle X-ray scattering (WAXS), powder X-ray diffractometer (PXRD), and cross polarization/magic angle spinning solid-state $^{13}C$ nuclear magnetic resonance spectroscopy (CP/MAS solid-state $^{13}C$ NMR). The specimen was prepared in forms of powder, sheet and pallet. With the comparison of the obtained crystallinity indices of the cellulose, the effects of the analysis instrument, the sample preparation and analysis method were investigated. Among three instruments, the crystallinity indices by PXRD and NMR had a good relationship and reproducibility, and WAXS gave the crystallinity index with poor reproducibility. In the case of analysis methods of crystallinity indices, the Segal method showed higher value than that of the Ruland-Vonk method. We expect that this study would be applicable to evaluate the crystallinity index of various cellulose materials with accuracy and reproducibility.

• Journal of the Korean Wood Science and Technology
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• 제26권4호
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• pp.20-25
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• 1998

Radial variation of crystalline state in a stem of Chamaecyparis obtusa E. was examined by x-ray diffraction analyses. Relative crystallinity and degree of crystallite orientation showed significant differences between juvenile and adult wood. That is, Relative crystallinity increased with increasing the age from pith to about 20th annual ring, after which it reached a more or less constant value. On the other hand, degree of crystallite orientation decreased outward from pith to about 10 years and presented almost a constant value thereafter. Crystal width by Scherrer's equation did not show any significant differences between juvenile and adult wood. Therefore, it was considered that crystallinity index and degree of crystallite orientation by x-ray diffraction method could be used for evaluating wood quality.

• E2M - 전기 전자와 첨단 소재
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• 제10권7호
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• pp.713-718
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• 1997

Polyaniline free standing films cast from N-methyl-2-pyrrolidinone(NMP) solution, camphorsulfonic acid(HCSA), dodecylbenzensulfonic acid(HDBSA), inorganic matter(carbon black, graphite) and metal(silver) were prepared by processings. The properties of these films such as crystallinity, near-infrared absorption spectra and conductivity were investigated. The HCSA and HDBSA doped polyaniline films cast from m-cresol and chloroform solvents showed the metallic property and high crystallinity, respectively. The value of conductivity in the HCSA doped polyaniline film obtained 180 S/cm. We have obtained the value of conductivity 200 S/cm in the metal(silver) doped polyaniline film, which is higher than that of the HCSA doped polyaniline film. The metal(silver) doped polyaniline film shows good properties as a electromagnetic shielding material.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.63-69
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• 2005

The stability of low-speed spinning process exhibiting spinline flow-induced crystallization (FIC) with no neck-like spinline deformation has been investigated using the method of linear stability analysis. Effects of various process conditions such as fluid viscoelasticity and the spinline cooling on the spinning stability have been found closely related to the development of the spinline crystallinity. It also has been found that the FIC makes the system less stable or more unstable than no FIC cases when the spinline crystallinity reaches its maximum possible value, whereas the FIC generally stabilizes the system if the crystallinity doesn't reach its maximum value on the spinline. It is believed that the destabilizing effect of the FIC on low-speed spinning when the crystallinity is fully developed on the spinline is due to the reduction of the real spinning length available for deformation on the spinline. On the other hand, the increased spinline tension caused by the FIC when the maximum crystallinity is not reached on the spinline and thus no reduction in the spinning length occurs, makes the sensitivity of spinline variables to external disturbances smaller and hence stabilizes the system. These linear stability results are consistent with the findings by nonlinear transient simulation, as first reported by Lee et al. (2005b).

• KSBB Journal
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• 제13권2호
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• pp.162-167
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• 1998

The adsorption behaviors of two major cellulase components, endo I and exo II, from Trichoderma viride were investigated using $\alpha$-celluloses with different correlation crystallinity index(Cc) as substrates. The adsorption of cellulase enzyme components was significantly affected by the reaction condition and the physicochemical properties of the cellulose. The $\alpha$-cellulose was hydrolyzed in the presence of cellulase for various periods. The correlation crystallinity index of $\alpha$-cellulose increased with increasing the hydrolysis time. The adsorption was apparently found to obey the first-order kinetics, and the adsorption activation energy(Ea) was calculated from the adsorption rate constant(ka). The value of adsorption rate constant for endo I was larger than that of exo II. This means that endo I are adsorbed more rapidly than exo II. With the increase in correlation crystallinity index, the values of the adsorption rate constants for endo I and exo II decreased, respectively. The activation energy for the adsorption of exo II on the cellulose also was larger than that of endo I. Also adsorption activation energy of endo I and exo II increased with an increase in the crystallinity of sample cellulose.

• 펄프종이기술
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• 제45권3호
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• pp.59-68
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• 2013

The cotton contains various impurities such as protein, wax, pectins, coloring matter, even though cotton has been a major source of pure cellulose. The purification processes have been commonly applied to obtain the pure cellulose. However the excessive purification treatments could lead to the damage in the cellulose structure which could result in the degradation of cellulose and the limited application of cotton cellulose. In this study, the changes in cellulose structural properties such as crystallinity and DP(degree of polymerization) by the various conditions of the purification processes were investigated. The less toxic agents such as hydrogen peroxide and sodium silicate were applied for the purification treatment in this study. The increase in the process times, the temperature and the applied amount of chemical agents resulted in the more purified cellulose. The DP of cotton cellulose was increased at the first weak conditions by the reduction of small molecules such as pectin, wax, and so on. Especially the 2 % addition amount of $H_2O_2$ with $Na_2SiO_3$ resulted in the higher value in the DP and the brightness compared to the 1.5 % addition amount of $H_2O_2$. However, the 4 % addition amount of $H_2O_2$ with $Na_2SiO_3$ showed the decreased value because of excessive treatment. In case of the changes in the crystallinity (Gjk), the highest value of the crystallinity was obtained by the 2% addition amount of $H_2O_2$ on the cotton cellulose, which showed similar with the change in the DP.

• E2M - 전기 전자와 첨단 소재
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• 제10권1호
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• pp.54-60
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• 1997

The electrical and electromagnetic shielding properties have been investigated in polyaniline free standing films with different degrees of elongation cast from N-methyl 2-pyrrolidone(NMP) solution and camphorsulfonic acid(HCSA) doped polyaniline film. The degree of crystallinity of the crosslinked films increased with increasing the draw ratio. For the case of the oriented films doped with hydrochloric acid, we have the values of conductivities up to 173 S/cm. It is considered that the physical micro-crystalline crosslinking domains act as nucleation sites for the increase of relative crystallinity during stretching. We have obtained the value of conductivity 210 S/cm in the HCSA doped polyaniline film cast from the solvent of m-cresol, which is higher than that of the crosslinking oriented films. The electromagnetic shielding efficiency of HCSA doped polyaniline film obtained 37-41 dB in the frequency range of 10MHz-1GHlz, which is higher than that of the crosslinking oriented films. The higher value of electromagnetic shielding efficiency of HCSA doped polyaniline film suggests strong possibility of electromagnetic shielding material.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.485-488
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• 2006

In order to investigate the possibility of waste mushroom logs as biomass resource chemical and physical characteristics of normal woods and waste mushroom logs such as crystallinity value, energy consumption, total sugar yield after hydrolysis chemical compounds and molecular weight distribution after acid hydrolysis, were examined. In the results, crystallinity of waste mushroom logs which were three year passed after the inoculation was decreased drastically from 49% to 33% during the cultivation. Lignin contents as chemical compounds of normal woods and waste mushroom logs were 21.07% and 18.78%, respectively. By the results of measurement of energy consumption, the size reduction of normal woods required a significantly higher energy than that of waste mushroom logs. In the hydrolysis, total sugar yield by enzyme and acid hydrolysis were high in waste mushroom logs(53% 57.5%) than in normal woods(42.9%, 47.17%). According to the molecular weight distribution using GPC, low molecular weight compounds were distributed in waste mushroom logs. Based on these results, waste mushroom logs have enough potential as material for developing alternative energy because of easily conversion to sugar by various hydrolysis methods and requirement of low energy consumption during size reduction.

• 한국결정성장학회지
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• 제12권6호
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• pp.299-303
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• 2002

The relationship of crystallinity between defects distribution with (100) ZnTe/GaAs using HWE growth was investigated by four crystal rocking curve (FCRC) and transmission electron microscopy (TEM). The thickness dependence of crystal quality in ZnTe epilayer was evaluated. The FWHM value shows a strong dependence on ZnTe epilayer thickness. For the films thinner than 6 ${\mu}{\textrm}{m}$, the FWHM value decreases very steeply as the thickness increases. For the films thicker than 6 ${\mu}{\textrm}{m}$, it becomes an almost constant value. At the thickness of 12 $\mu\textrm{m}$ with the smallest value of 66 arcsec. which is the best value so far reported on ZnTe epilayers was obtained. Investigation into the nature and behavior of dislocations with film thickness in (100) ZnTe/(100)GaAs heterostructures grown by Hot Wall Epitaxy (HWE). This film defects range from interface to 0.7 ${\mu}{\textrm}{m}$ thickness was high density, due to the large lattice mismatch and thermal expansion coefficients. The thickness of 0.7~1.8 ${\mu}{\textrm}{m}$ was exists low defect density. In the thicker range than 1.8 ${\mu}{\textrm}{m}$ thickness was measured hardly defects.

• Journal of Electrochemical Science and Technology
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• 제8권1호
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• pp.69-76
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• 2017

Crystallization of one-dimensional porous tin oxide during the anodic oxidation of tin at ambient temperatures is reported. Remarkable crystallinity is achieved when a substrate with a high elastic modulus (e.g., silicon) is used and the tin coating on it is very thin. It is suggested that the compressive stress applied to the anodic tin oxide during the anodization process is the key factor affecting the degree of crystallinity. The measured value of the stress generated during anodization matches well with the range of the most favorable theoretical pressure (stress) for crystallization.