• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.471-472
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• 2007

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• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.1
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• pp.58-63
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• 2010

The glass-ceramics made from the mixture of coal bottom ash, produced from a thermal power plant mixed with $Na_2O$ and $Li_2O$ was fabricated and their crystallization behavior was studied using a non-isothermal analyzing method. The temperature for 50% crystallization was higher than the exothermic peak temperature $T_p$ at DTA curve and the quickest crystallization temperature was much the same as $T_p$ as identified from the relationships of crystallized fraction and crystallization rate with temperature. By using Kissinger equation describing a crystallization behavior, the activation energy (262 kJ/mol), the Avrami constant (1.7) and the frequency ($5.7{\times}10^{16}/s$) for crystallization were calculated from which the nepheline crystal could be expected as showing an 1~2-dimensional surface crystallization behavior mainly with some bulk crystallization tendency at the same time. The actual observation of microstructure using SEM showed the considerable amount of surface crystals of dendrite and the bulk crystals with low fraction, so the prediction by the Kissinger equation was in accord with the crystallization behavior of glass-ceramics fabricated in this study.

• Journal of the Korean Ceramic Society
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• v.32 no.12
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• pp.1331-1336
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• 1995

The glass-ceramics for ferro-electric were made from compositions of 70PbO.16TiO2.8SiO2.4B2O3.2AlPO4 (wt%) and 67.5PbO.20TiO2.8.5SiO2.2B2O3.2AlPO4 (wt%). The crystallization kinetics for PbTiO3 crystalline phase formation from glass was studied using non-isothermal DSC techniques. The values of activation energy, ΔE using variables of heating rate and temperature were calculated at various reaction fractions obtained from peak area over DSC. The results indicated that activation energy was lowest at 60% reaction fractions and the activation energy of glass containing 20.0 wt% TiO2 is higher than that of glass containing 16.0 wt% TiO2. The crystallization mechanism was three dimensional growth (n=4).

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2369-2376
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• 2011

Effect of heat treatment of carbon nanofibers (CNF) on electrical properties and crystallization behavior of polypropylene was reported. Two types of CNFs (untreated and heat treated at 2300 $^{\circ}C$) were incorporated into polypropylene (PP) using intensive mixing. A significant drop in volume resistivity was observed with composites containing untreated 5 wt % and heat treated 3 wt % CNF. In non-isothermal crystallization studies, both untreated and heat treated CNFs acted as nucleating agents. Composites with heat treated CNFs showed a higher crystallization temperature than composites with untreated CNFs did. TEM results of CNF revealed that an irregular structure of CNFs can be converted into the continuous graphitic structure after heat treatment. Furthermore, STM showed that the higher carbonization temperature leads to the higher graphite degree which presents the larger carbon network size, suggesting that a more graphitic structure of CNFs led to a higher crystallization temperature of PP.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.243-246
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• 2001

열가소성 고무탄성체인 폴리에테르에스테르계 고분자는 결정에 의한 물리적 가교를 형성할 수 있는 하드세그멘트 블록과 비결정성의 소프트세그멘트 블록으로 구성되어 탄성을 발현하는 성질을 갖는다. 이때 하드세그멘트의 함량의 변화는 고분자의 결정화 특성을 변화시켜 최종단계에서의 물성에 큰 영향을 미친다. 본 연구에서는 하드세그멘트가 PBT 구조로 이루어지고 소프트세그멘트는 PTMGT 구조를 갖는 4GT/PTMGT 고분자의 결정화 거동을 분석하였다. (중략)

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.611-616
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• 2011

In the study, annealing temperature was optimized by comparing with avrami crystallization rate and constant (k) using non-oriented PLA film as a base film. Crystallization rate constant of PLA film was 1.64, 1.68, and 1.26 at $120^{\circ}C$, $130^{\circ}C$, and $140^{\circ}C$, respectively. Annealing temperature was mainly affected on the surface properties such as rougnness (Ra) and kinetic friction coefficient (${\mu}_k$). Roughness of PLA film was 0.006 ${\mu}m$ at $80^{\circ}C$ and increased to 0.009 ${\mu}m$ 0.015 ${\mu}m$, 0.027 ${\mu}m$, and 0.029 ${\mu}m$ at $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$ and $140^{\circ}C$, respectively. Kinetic friction coefficient decreased 0.45 to 0.43, 0.33, 0.31, 0.27 as annealing temperature was at $80^{\circ}C$, $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$, and $140^{\circ}C$, respectivly. In addition, rate constant (k) was 0.58, 0.46, and 0.39 with adding 1 wt%, 3 wt%, and 5 wt% talc, respectively.

• Carbon letters
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• v.15 no.1
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• pp.50-56
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• 2014

We prepared ethylene vinyl alcohol (EVOH)/graphene oxide (GO) membranes by solution casting method. X-ray diffraction analysis showed that GOs were fully exfoliated in the EVOH/GO membrane. The glass transition temperatures of EVOH were increased by adding GOs into EVOH. The melting temperatures of EVOH/GO composites were decreased by adding GOs into EVOH, indicating that GOs may inhibit the crystallization of EVOH during non-isothermal crystallization. However, the equilibrium melting temperatures of EVOH were not changed by adding GOs into EVOH. The oxygen permeability of the EVOH/GO (0.3 wt%) film was reduced to 63% of that of pure EVOH film, with 84% light transmittance at 550 nm. The EVOH/GO membranes exhibited 100 times better (water vapor)/(oxygen) selectivity performance than pure EVOH membrane.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.63-68
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• 2019

We investigated the effects of Al2O3 addition on (1-x)Li2B4O7-xAl2O3 (LBAO; x = 0, 0.005, 0.01, 0.05, 0.07, and 0.1) glasses. The glasses were synthesized by a conventional melt-quench method. Structural transformations of the LBAO glasses were assessed via X-ray diffraction analysis. Estimations of ΔT, KGS = (Tc-Tg)/(Tm-Tc), activation energy, and the Avrami parameter were performed using differential thermal analysis and differential scanning calorimetry. An interpretation of non-isothermal kinetics of the crystallization process is presented using the modified Ozawa equation. The activation energy E increased from 3.3 to 3.5 eV for the LBAO (x < 0.01) glasses whereas those of the LBAO (x > 0.05) glasses slightly increased from 3.75 to 4.05 eV. The exponent n was estimated to be 3.9 ± 0.1 for the LBAO (x < 0.01) glasses and 3.2 ± 0.02 for the LBAO (x > 0.05) glasses. Microstructural characterization of the glassy and crystalline phases using atomic force microscopy was investigated. The effects of Al2O3 on the LBAO glasses include a decreased nucleation rate in the crystallization process and a significantly reduced crystal size.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.3
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• pp.236-243
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• 1995

Since amorphous alloys have been known to have better mechanical and chemical properties than crystalline alloys of the same composition, a great number of studies on the formation of Al-based amorphous alloys have been carried out actively. However, little has been obtained about the effect of Rare-Earth metal and Transition metal addition on amorphous phase formed by melt spinning method. This study included fabrication of amorphous alloy $Al_{85}Ce_5Ni_{10}$ by melt spinning methods and DTA, XRD, TEM analysis to determine crystalization behavoir. Annealing treatments were carried out in Ar atmosphere under isothermal and nonisothermal conditions. The diffraction pattern of non-heated ribbons showed broad form characteristic of glass metallic alloy. The crystallization of amorphous $Al_{85}Ce_5Ni_{10}$ takes place eutedtoidly by homogeneous formation of Al and MS-1, followed by precipitation of the $Al_{11}Ce_3$ and later $MS-1{\rightarrow}Al_3Ni$ transformation.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.141-147
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• 2005

Nanomaterial $TiO_2-SiO_2$ was synthesized by hydrolysis and condensation process using 2-propanol(2-PrOH) and was characterized by FT-IR, DSC, XRD and FE-SEM. FT-IR spectra were measured to investigate Ti-0-Si absorption peak. DSC thermal analysis results appllied to Ozawa equation were used to calculate to activation energy of crystallization. It was found that the changes of X-ray diffraction patterns and FWHM obtained XRD measurement depended on calcination temperature. In FE-SEM analysis, particle size changed by quantity changes of Ti-alkokide.