• Journal of the Korean Applied Science and Technology
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• v.25 no.2
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• pp.232-239
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• 2008

Separation of naphthalene from naphthalene and 2-methylnaphthalene mixture has been studied by layered melt and solution crystallization using ethylalcohol. Purity and yield of naphthalene depended mainly on the cooling rate: The effective distribution coefficient ($K_{eff}$) as the degree of impurity removal was observed to decrease with the decreasing in cooling rate. Purity of naphthalene can be enhanced to $5{\sim}7%$ by melt crystallization using 90% naphthalene and the purity of naphthalene can be obtained to be 99% up by solution crystallization.

• Macromolecular Research
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• v.17 no.11
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• pp.842-849
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• 2009

Polycarbonate (PC)/sulfonated polystyrene (SPS) ionomer/organoclay nanocomposites were prepared by a solution intercalation process using the SPS ionomer as a compatibilizer. The effect of an organoclay on the melt crystallization behavior of the ionomer compatibilized PC were examined by differential scanning calorimetry (DSC). The melt crystallization behavior of PC was dependent on the extent of organoclay dispersion. The effect of the ionomer loading and cation size on intercalation/exfoliation efficiency of the organoclay in PC/SPS ionomer matrix was also studied using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Dispersion of the organically modified clay in the polymer matrix improved with increasing ionomer compatibilizer loadings and cation size. The SPS ionomer compatibilized PC/organoclay nanocomposite showed enhanced melt crystallization compared to the SPS ionomer/PC blend. Well dispersed organoclay nanocomposites showed better crystallization than the poorly dispersed clay nanocomposites. These nanocomposites also showed better thermal stability than the SPS ionomer/PC blend.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.9-16
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• 1995

Biodegradable poly (I ,4-butanediol succinate) (PBS) was synthesized from 1,4-butanediol and succinic anhydride. The glass transition temperature of poly (I, 4-butanediol succinate) was revealed at $73^{\circ}C$. The crystallization and cold crystallization of the polymers were investigated as a function of holding time in melt state, cooling rate. reheating, and molecular weight. Chain scission and/or cmsslinking did not occur in the melt state at var.ious holding times. Slower scanning rate can allow more times for nucleation, rearrangement, and packing of the polymer chain, so the onset temperature of crystallization from the melt was increased. PBS crystallized from the melt was found to have spherulitic structure. The degradation behavior of PBS was studied under basic conditions and with microorganisms using the modified ASTM method. In the basic solution. PBS lost up to 85% of its mass within two days. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples.

• Current Applied Physics
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• v.18 no.11
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• pp.1289-1293
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• 2018

The influence of crystallization treatment on the structure, magnetic properties and magnetocaloric effect of $Gd_{71}Ni_{29}$ melt-spun ribbons has been investigated in detail. Annealing of the melt-spun samples at 610 K for 30 min, a majority phase with a $Fe_3C$-type orthorhombic structure (space group, Pnma) and a minority phase with a CrB-type orthorhombic structure (space group, Cmcm) were obtained in the amorphous matrix. The amorphous melt-spun ribbons undergo a second-order ferromagnetic to paramagnetic phase transition at 122 K. For the annealed samples, two magnetic phase transitions caused by amorphous matrix and $Gd_3Ni$ phases occur at 82 and 100 K, respectively. The maximum magnetic entropy change $(-{\Delta}S_M)^{max}$ is $9.0J/(kg{\cdot}K)$ (5T) at 122 K for the melt-spun ribbons. The values of $(-{\Delta}S_M)^{max}$ in annealed ribbons are 1.0 and $5.7J/(kg{\cdot}K)$, corresponding to the two adjacent magnetic transitions.

• Polymer(Korea)
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• v.38 no.5
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• pp.613-619
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• 2014

The polypropylene/polyamide elastomer (PP/PAE) blends were prepared by melt mixing. PP and PAE in PP/ PAE were immiscible completely. The size of PAE domains was large and the clear gap in the interface between PP and PAE existed, which did not meet the conditions enhancing toughness of polymers by elastomer. Therefore, maleic anhydride grafted polypropylene (MP) was used to improve the miscibility between PP and PAE. The miscibility between PP and PAE was improved and the size of dispersed phase PAE decreased by introducing MP. The crystallization of PP became easier by introducing PAE as a nucleating agent. With the increase of PAE content, the melt-crystallization temperatures of PP components in PP/PAE/MP blends increased gradually. The melt-crystallization of the polytetramethylene oxide segment of PAE component in PP/PAE blends were hampered by PP component. In addition, PAE can enhance significantly the toughness of PP, and the tensile strength and modulus did not decrease.

• Polymer(Korea)
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• v.24 no.5
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• pp.656-663
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• 2000

The Effects of thermal history during the melt spinning process on the mechanical properties and crystallinity of polylactic acid (PLLA) fibers have been studied. Thermal history applied on PLLA during the melt process caused the decrease of number-average molecular weights and this resulted in the lowering of orientation and crystallinity in PLLA fibers. As a result, the longer applied thermal history, the less tensile strength and modulus, and the higher elongation at break. It was also found that primary factor for controlling crystallinity of PLLA fiber was the stress induced crystallization while the thermal induced crystallization had a little effect on the crystallinity of PLLA fibers. However, the thermal induced crystallization turn out to be important in the crystallinity developed by annealing of PLLA fibers.

• Journal of Hydrogen and New Energy
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• v.18 no.4
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• pp.399-405
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• 2007

The hyper-eutectic Mg-33.5%Ni alloy was rapidly solidified by melt spinning process. The melt-spun Mg-33.5%Ni has amorphous structure and crystallization occurred above $162^{\circ}C$. The hydriding and dehydriding rates of melt-spun Mg-33.5%Ni increased with cycle and high rate of hydrogen storage occurred at 3rd cycle. The maximum hydrogen amount absorbed in melt-spun Mg-33.5%Ni at $300^{\circ}C$ is about 4.5%.

• Proceedings of the Korean Magnestics Society Conference
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• 1995.05a
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• pp.74-75
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• 1995

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.655-659
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• 1998

The effect of quenching speed of melt-spinning on intrinsic coercivity ($_iH_c$$) of annealed ribbons and the crystallization behavior from amorphous $Nd_{14.73}Fe_{78.67}B_{6.60}$ alloy have been studied. We have found that the intrinsic coecivity for annealed melt-spun ribbon is reduced with increasing of quenching rate. $\alpha$-Fe and $Fe_3B$ were formed as intermediate phases prior to the formation of $Nd_2Fe_{14}B$ phase during crystallization. The $Fe_3B$ is disappeared with crystallization of $Nd_2Fe_{14}B$ phase. But the $\alpha$-Fe phase is retained in fully crystallized ribbon by annealing. The intrinsic coercivity loss of annealed ribbon with increasing of quenching speed is believed to be due to existence of soft magnetic phase $\alpha$-Fe in annealed ribbons.

• Clean Technology
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• v.12 no.3
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• pp.157-164
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• 2006

In order to purify 2-methylnaphthalene as main impurity included in naphthalene, SLE (solid-liquid equilibria) on two components system including naphthalene and 2-methylnaphthalene were measured and a layered melt crystallization has been studied. SLE in the present system is shown a simple eutectic mixture and the experimental results using DSC method is similar to the static method. Purity and yield of naphthalene in crystal depended mainly on the cooling rate: Increasing cooling rate, the purity of naphthalene in crystal increase, whereas the yield of that decrease. The effective distribution coefficient (Keff) as the degree of impurity removal was observed to decrease with decreasing of cooling rate. Therefore, the purity of naphthalene by melt crystallization can be enhanced to 5~7 %.