• Polymer(Korea)
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• v.24 no.1
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• pp.128-132
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• 2000

The miscibility between poly(vinyl chloride) (PVC) and polycaprolactone (PCL)-polyamide block copolymer whose content of PCL block is 62.7 wt%, was studied by differential scanning calorimetry. The PCL segment in the block copolymer and PVC has the miscibility showing single glass transition temperature (T$_{g}$). The miscible PVC molecule inhibited the crystallization of PCL segment, making an amorphous homogeneous phase of PCL and PVC segments at high PVC content. The blends had rubber elasticity at the temperature range between the T$_{g}$ of amorphous homogeneous phase of PCL and PVC segments and the melting temperature of polyamide segment, when both phases coexist.ist.

• Journal of Microbiology and Biotechnology
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• v.17 no.4
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• pp.600-603
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• 2007

The effect of a water-miscible ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate $([BMIM][BF_4])$, on the horseradish peroxidase (HRP)-catalyzed oxidation of 2-methoxyphenol (guaiacol) with hydrogen peroxide $(H_2O_2)$ was investigated. HRP maintains its high activity in the aqueous mixtures containing various concentrations of the ionic liquid and even in 90% (v/v) ionic liquid. In order to minimize the effect of solution viscosity on the kinetic constants of HRP catalysis, the enzymatic reactions in the subsequent kinetic study were performed in water-ionic liquid mixtures containing 25% (v/v) ionic liquid at maximum. As the concentration of $[BMIM][BF_4]$ increased for the oxidation of guaiacol by HRP, the $K_m$ value increased with a slight decrease in the $K_{cat}$ value: The $K_m$ value increased from 2.8 mM in 100% (v/v) water to 22.5mM in 25% (v/v) ionic liquid, indicating that ionic liquid significantly weakens the binding affinity of guaiacol to HRP.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.29-40
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• 2000

Highly purified Cerrena unicolor laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) caused the demethoxylation of milled wood lignin and several lignin related substances. The constitutive form of the enzyme produced extracellularly by C. unicolor fermenter culture was isolated and purified by ion-exchange chromatography on the DEAE-Toyopearl column and by affinity chromatography on a ConA-Sepharose and Syringyl-AH-Sepharose 4B columns. The enzyme was further immobilized on functionalized porous glass (CPG) and keratin coated CPG. The demethylating activity was monitored both by estimation of released methanol and by detection of the level of methoxyl groups (also in some water miscible solvents) after incubation of lignin materials with laccase preparations (free and immobilized). The effects of the incubation time and temperature on the demethoxylating activity of immobilized laccase preparations were also studied.

• Analytical Science and Technology
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• v.8 no.4
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• pp.511-517
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• 1995

A cationic water soluble porphyrin (5,10,15,20-tetrakis (l-methyl-pyridinium-4-yl)porphyrin, $H_2tmpyp^{4+}$) and its metalloporphyrins (MP) were easily extracted into acetonitrile separated by addition of sodium chloride ($4mol\;dm^{-3}$) in the presence of sodium perchlorate, where M denotes $Zn^{2+}$, $Cu^{2+}$, $Co^{3+}$, $Fe^{3+}$, and $Mn^{3+}$ and $P^{2-}$ is porphyrinate ion. The extracted ion-pair complexes were completely dissociated to $[MP(ClO_4)_3]^+$, and $[MP(ClO_4)_2]^{2+}$. The extraction and the dissociation constants were determined by taking into account of the partition constant of sodium perchlorate ($K_D=1.82{\pm}0.01$). The chemical properties of the separated acetonitrile phase as $E_{T(30)}$ and $D_{II,I}$ were determined and compared with other water miscible solvents (acetone, actonitrile, 1,4-dioxane, tetrahydrofuran, 1-propanol and 2-propanol). Furthermore, a sensitive and selective method was proposed for the determination of a subnanogram amount of copper(II) in natural water samples by using the present salting-out method and the porphyrins.

• Textile Coloration and Finishing
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• v.24 no.2
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• pp.145-151
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• 2012

Polymer alloys of poly(ethylene terephthalate)(PET) and nylon6(PA6) which were not miscible each other by themselves were successfully prepared through melt compounding using a twin-screw extruder by utilizing epoxy as reactive compatibilizer. At the epoxy(DGEBA) amount of 0.5~2wt%, the domain size(average diameter) of the discontinuous phase could be reduced up to 0.2${\mu}m$ from 1-5${\mu}m$ that of the simple blend without epoxy. The reaction was presumed to happen mostly at interphase from the result of maximum increase of melt viscosity at the middle range of PET/PA6 blend ratio. It is expected that alloy fibers of PET/epoxy/PA6 with enough mechanical strength for use can be prepared.

• Polymer(Korea)
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• v.28 no.6
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• pp.509-518
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• 2004

Microdomain structures and crystallization behavior of the binary blends consisting of an asymmetric block copolymer and a homopolymer were investigated using small-angle X-ray scattering (SAXS), optical micro scope (OM) and differential scanning calorimetry (DSC). Poly(methyl methacrylate)-block-polystyrene block copolymer (PMMA-b-PS) (weight fraction of PMMA =0.53) was mixed with low molecular weight poly(vinylidene fluoride) (PVDF). As the PVDF concentration was increased, the morphological change from a lamellar to a cylindrical structure occurred. The crystallization of PVDF significantly disturbed the orientation of the pre-existing microdomain structure, resulting in a poorly ordered morphology. In the blends, PVDF exhibited unique crystallization behavior due to the PMMA block which is preferentially miscible to PVDF and the space constraint imposed by the microdomains.

• Macromolecular Research
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• v.10 no.3
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• pp.135-139
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• 2002

Blends of the linear bisphenol-A polycarbonate (L-PC) and randomly branched bisphenol-A polycarbonate (Br-PC), prepared by co-rotating twin screw extrusion, were investigated using differential scanning calorimetry (DSC), sag resistance time tester, extensional rheometry, and advanced rheometric expansion system (ARES). From the DSC results, the glass transition temperature (T$_{g}$) of the L-PC/Br-PC blend was increased with the increase of Br-PC in the blend, and the blend showed a single T$_{g}$, which suggests a miscible blend. The sag resistance time of the L-PC/Br-PC blend was increased with the increase of Br-PC in the blends. From the results of rheological measurements of the L-PC/Br-PC blends, the extensional viscosity and the complex viscosity of the blends were found to increase with the increase of Br-PC in the blends. The increase of extensional viscosity and complex viscosity was related with the increase of sag resistance time with the Br-PC in the L-PC/Br-PC blends.nds.

• Macromolecular Research
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• v.17 no.9
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• pp.682-687
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• 2009

Nanofibrous membranes of poly(D,L-lactic acid)/chitin blend were prepared by electro spinning for a barrier of guided tissue regeneration. A miscible solution was obtained by the blending chitin-salt complex into 1-methyl-2-pyrrolidone solution of poly(D,L-lactic acid). The properties of the blend were examined for nanofibrous fabrication. The viscosity of the blend solution was increased significantly due to chain entanglement despite the low ratio of chitin to poly(D,L-lactic acid). An interaction between two polymeric compositions was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction detected an appreciably ordered microstructure in the nanofiber of the blend. A membrane of thinner nanofibers was fabricated by electro spinning the chitin blend. The permeability of the membranes was examined using bioactive model compounds.

• Microbiology and Biotechnology Letters
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• v.7 no.4
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• pp.211-216
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• 1979

Air lift fermentor (ALF) is widely used for production of single-cell protein (SCP) from hydrocarbon and other carbon sources, because oxygen transfer efficiency is believed to be superior in the ALF to that in other conventional fermentors. However, the performance of ALF in terms of mixing is somewhat questionable. In this research, we studied about the performance of the ALF in SCP production using methanol fermentation process as a model system. The results show that ALF could be employed for SCP production or other fermentation processes when substrate is miscible and used at low concentration. With a high substrate concentration, it must be operated under high pressure or low dilution rate to meet the adequate oxygen transfer requirement.

• Polymer(Korea)
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• v.25 no.5
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• pp.649-656
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• 2001

Miscibility of poly(4-vinylpyridine) (P4VP) blends with poly(vinyl acetate-co-vinyl alcohol) (VAc-VAL copolymers) was investigated as a function of comonomer composition of VAc-VAL copolymers. Differential scanning calorimetry (DSC) and thermo-optical microscopic (TOM) analysis confirmed that P4VP is miscible with VAc-VAL copolymers containing more than 30 mole% VAL. Fourier transform inflated (FT-IR) spectroscopic analysis revealed that the strong intermolecular hydrongen bonding interaction between the vinylpyridine and VAL hydroxyl group was formed. Theoretical phase diagram was constructed by the calculation using the Association model, a thermodynamic model for hydrogen-bonded polymer blend systems developed by Coleman et al. The calculated theoretical binodal phase diagrams were in good agreement with the experimentally determined cloud point curves.