• Polymer(Korea)
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• v.24 no.4
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• pp.513-519
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• 2000

The effect of petroleum resin as a tackifier for polyalphaolefin (APAO) hot melt adhesive on thermal properties, crystallinity and adhesion strength was investigated. The presence of petroleum resin resulted in the melting temperature decrease in APAO/petroleum blend, especially, in APAO with low ethylene content/C$_{5}$ petroleum blend. It was also found that petroleum resin caused the decrease of crystallinity regardless of ethylene content in APAO. The maximum adhesion strength was found to be at 50/50 (APAO/petroleum) composition. $C_{5}$ resin was more effective to increase adhesion strength than $C_{9}$ for APAO with high ethylene content. In addition, it was found that the adhesion strength was improved with the decrease of crystallinity in APAO/petroleum resin hot melts.

• Polymer(Korea)
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• v.34 no.6
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• pp.522-526
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• 2010

Bacterial cellulose is produced by the bacterium Gluconacetobacter xylinus, which forms a nanofibrous pellicle in its culture medium. We studied properties of the bacterial cellulose such as crystallinity, viscosity, morphology, and mechanical properties according to the carbon source. Static cultures of Gluconacetobacter sp. V6 were performed in three kinds of media: standard Hestrin-Schramm medium, and modified medium with either glycerol or molasses as carbon sources. Cell growth and cellulose yield were increased in the glycerol and molasses media. The culture in the glycerol medium improved the physical properties of cellulose such as crystallinity, intrinsic viscosity, and breaking stress. However, the culture in the molasses medium decreased crystallinity, crystallite size, and intrinsic viscosity of cellulose. In summary, the cellulose yield was remarkably improved in the molasses medium, but with inferior structural properties.

• Journal of the Korean Ceramic Society
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• v.42 no.4
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• pp.276-281
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• 2005

$LiNi_{1-y}M_{y}O_{2}(M=Zn^{2+},\;Al^{3+},\;and\;Ti^{4+},\;0.000\{\le}y{\le}0.100)$ were synthesized by the combustion method by calcining in $O_{2}$ stream at $750^{\circ}C$ for 36 h. XRD analyses, observation by FE-SEM and measurement of the variation of discharge capacity with the number of cycles were carried out. The composition $LiNi_{0.99}M_{0.01}O_{2}(M=Zn^{2+},\;Al^{3+},\;and\;Ti^{4+})$ of all the compositions showed relatively good electrochemical properties. $LiNi_{0.99}M_{0.01}O_{2}$ exhibited poor crystallinity and $LiNi_{0.99}M_{0.01}O_{2}$ showed the cation mixing of large fraction. $LiNi_{0.99}M_{0.01}O_{2}$ with improved cycling performance showed good crystallinity and the cation mixing of small fraction.

• Journal of the Korean Applied Science and Technology
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• v.21 no.3
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• pp.231-237
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• 2004

Ga-MFI was synthesized by a hydrothermal process at atmospheric pressure. The effect of mole ratios of reactants on crystallization was also investigated thoroughly. The characteristics of synthesized Ga-MFI was compared with ZSM-5. The synthesis of Ga-MFI was carried out with five different mole-compositions of $\underline{a}SiO_2-\underline{b}Ga_2O_3-\underline{c}Na_2O-\underline{d}TPA_2o-\underline{e}H_2O$. The synthesized Ga-MFI and ZSM-5 were characterized by XRD and FT-IR. The inorganic cation ($Na^+$) and water played an important role in crystallinity and the organic cation ($TPA^+$) as a template played a great influence on yields. With the increase in the amount of $Ga^{3+}$, crystallization time was increased. With a fixed $SiO_2/Ga_2O_3$ ratio of 400, the optimum reaction condition was obtained at $H_2O/SiO_2$=30${\sim}$35, $Na_2O/SiO_2$=0.5${\sim}$0.6, and $TPA_2O/Na_2O$=1${\sim}$1.25. In these cases, the crystallinity and yield were more than 95% and 90%, respectively. By comparing IR spectrum of Ga-MFI with those of ZSM-5 and silicalite, it was found that Ga-MFI showed a unique peak at 970 $cm^{-1}$, which may be used to identify Ga-MFI from ZSM-5 and silicalite.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.785-791
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• 2001

High dielectric (Ba, Sr) TiO$_3$ thin films were etched in an inductively coupled plasma (ICP) as a function of Cl$_2$/Ar mixing ration. Under Cl$_2$(20)/Ar(80), the maximum etch rate of the BST films was 400 $\AA$/mim and selectivities of BST to Pt and PR were obtained 0.4 and 0.2, respectively. Etching products were redeposited on the surface of BST and resulted in varying the nature of crystallinity. Therefore, we investigated the etched surface of BST by x-ray photoelectron spectroscopy (XPS) atomic force microscopy (AFM) and x-ray diffraction (XRD). From the result of XPS analysis, we found that residues of Ba-Cl and Ti-Cl bonds remained on the surface of the etched BST for high boiling point. The morphology of the etched surfact was analyzed by AFM. A smoothsurface(roughness ~2.8nm) ws observed under Cl$_2$(20)/Ar(80), rf power of 600 W, dc bias voltage of -250 V and pressure of 10 mTorr. This changed the nature of the crystallinity of BST. From the result of XRD analysis, the crystallinities of the etched BST film under Ar only and Cl$_2$(20)/Ar(80) were maintained as similar to as-deposited BST. However, intensity of BST(100) orientation under Cl$_2$ only plasma was abruptly decreased. This indicated that CI compounds were redeposited on the etched BST surface and resulted in changed of the crystallinity of BST during the etch process.

• Polymer(Korea)
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• v.24 no.2
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• pp.281-286
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• 2000

A series of amorphous polyesters were synthesized from amorphous polyether and sebacoyl chloride. The structure and competition of the obtained aliphatic polyester were confirmed by $^1$H-NMR and FT-IR. The number average molecular weights (M$_{n}$) of the obtained polymer were ranging from 8000 ~ 15000. These polyesters showed no crystallinity and their glass transition temperatures (T$_{g}$) were around -77$^{\circ}C$. For comparison, aliphatic polyesters were also synthesized from poly(ethylene glycol) (PEG) with M$_{n}$ of 200, 400, and 1000. As the M$_{n}$ of PEG increased, the melting point of the obtained polyester increased, and the crystallinity of the obtained polyester increased showing 8.8%, 16.2%, and 46.7%, respectively.ively.y.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.4
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• pp.56-63
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• 2010

Microcrystalline cellulose (MCC) was prepared from Miscanthus in this study. Two pulping methods, soda pulping and alkaline sulfite pulping were applied as a pretreatment process. After pulping, two different bleaching processes such as $ClO_2$ treatment followed by $H_2O_2$ treatment and $O_3$ treatment followed by $H_2O_2$ treatment were carried out. Two concentration of $H_2SO_4$, 47% and 57% were applied to the purified Miscanthus cellulose as a acid hydrolysis process to make MCC. The crystallinity index and morphological properties of the produced MCC were evaluated with X-ray diffractometer and scanning electron microscopy. The MCC originated from the soda pulping sample showed the higher crystallinity index than that originated from the alkaline sulfite pulping sample. The two stages of treatmen twith $O_3$ and $H_2O_2$ resulted in the higher purified cellulose products.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.166-171
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• 2005

Fe-6Al-9Si(N) alloy powders were synthesized by hybrid process of chemical nitrification and mechanical milling. The nitriding treatment on Fe-6Al-9Si alloy powders formed $\gamma'-Fe_4N$ phase on the powders surface. The nitriding-treated powders were pulverized by horizontal high-energy ball milling machine. The longer ball milling time tended to reduce the size of alloy powders. In ball milling for 36h, extremely fine powders with about $7\~9wt\%$ nitrogen were obtained. Through X-ray diffraction analysis on the powders, it was found out that the longer milling time caused a disappearance of the crystallinity of $\alpha-Fe$ in the powders. TEM study confirmed that the powders is comprised of a few tens nano-meter sized crystals, including $\alpha-Fe$ phase with partially $\gamma'-Fe_4N$ phase. Hysteresis curves of the synthesized powders measured by VSM revealed lower saturation magnetization and higher coercivity, which seemed to be attributed to nitrogen-impregnation and severe residual stress developed during the high energy milling. Microstructure observation on the powder annealed at 873 K for 1 h showed 10 to 20 nm sized $\alpha-Fe$ crystal. Such a enhanced crystallinity significantly increased the magnetization and decreased the coercivity, which was attributed to not only the crystallinity but also residual stress relaxation.

• Corrosion Science and Technology
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• v.3 no.3
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• pp.112-117
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• 2004

This work investigated the material properties of Ni-P-B alloy electrodeposits obtained from a Ni sulfamate bath as a function of the contents of the P and B sources($H_3PO_3$ and dimethyl amine borane complex(DMAB), respectively) with/without additives. Chemical composition, residual stress, microstructure and micro hardness were investigated using ICP(inductively coupled plasma) mass spectrometer, flexible strip, XRD, TEM and micro Vickers hardness tester, respectively. From the results of the compositional analysis, it was observed that P and B are incorporated competitively during the electrodeposition and the sulfur from the additive is codeposited into the electrodeposit. The measured residual stress value increased in the order of Ni, Ni-P, Ni-B and Ni-P-B electrodeposits indicating that boron affects the residual tensile stress greater than phosphorus. As the contents of the alloying element sources of P and B increased, crystallinity and the grain size of the electrodeposit decreased. The effect of boron on crystallinity and grain size was also relatively larger than the phosphorus. It can be explained that the boron with a smaller atomic radius contributes to the increase of residual stress in the tensile direction and the larger restraining force against the grain growth more significantly than the phosphorus with a larger atomic radius. Introduction of an additive into the bath retarded crystallization and grain growth, which may be attributed to the change of the grain growth kinetics induced by the additive adsorbed on the substrate and electrodeposit surfaces during electrodeposition.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.132-136
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• 2002

Enhancement of crystallinity and exchange bias characteristics for NiFe/FeMn/NiFe trilayer with Si buffer layer fabricated by ion-beam deposition were examined. A Si buffer layer promoted (111) texture of fcc crystallities in the initial growth region of NiFe layer deposited on it. FeMn layers deposited on Si/NiFe bilayer exhibited excellent (111) crystal texture. The antiferromagnetic FeMn layer between top and bottom NiFe films with the buffer Si 50 ${\AA}$-thick induced a large exchange coupling field Hex with a different dependence. It was found that H$\sub$ex/ of the bottom and top NiFe films with Si buffer layer revealed large value of about 110 Oe and 300 Oe, respectively. In the comparison of two Ta and Si buffer layers, the NiFe/FeMn/NiFe trilayer with Si could possess larger exchange coupling field and higher crystallinity.