• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.1
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• pp.73-83
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• 1997

Most of the materials used in various industrial fields and also in our daily life are multi-component materials or composite materials, and it is well known that there are many cases where adhesion between the constituents within the bonded systems plays an important role. There are various types of performance evaluation tests for the bonded materials, among which tests for evaluating the bond performance under various conditions may be regarded as the most interesting ones for those engaged in work related to adhesion. I have studied on the mechanism of adhesion form the rheological standpoint with my colleagues, including some students from Korea, and I am very happy to be able to have a talk on some of our research works. In Japan, the so-called "adhesives" are usually classified into two categories;adhesives and pressure sensitive adhesives (PSA). Adhesives are the materials which solidify after bonding and are after used as the structural adhesives because the adhesive strength is comparatively strong. On the other hand, the pressure sensitive adhesives never solidify and are used as PSA tapes, labels or decals. About the adhesives, we have examined the dependence of adhesive strength(shear, tensile, peel) upon both temperature and rate of deformation, and found out some empirical rules which are applicable to most of the adhesive systems. We have also developed a simplified theory of adhesion, which is deseribed in terms of mechanical equivalent mode1 and a few failure criteria. Although some of the common rules can be accounted for according to this theory, it must be pointed out that a fracture mechanical approach ms inevitable especially in the region where the meehanical relaxation time of the adhesive is extremely large [W. W. Lim and H. Mizumachi]. About the pressure sensitive adhesives, we have studied on the PSA performance (peel, tack, holding power) as a function of both the viscoelastic properties and surface chemical properties of the materials, and found out some rules, and again we have developed a theory which deseribes the mechanism. And in addition, we have studied on the miscibility between linear polymers and oligomers, because PSA is generally manufactured by blending gums and tackifier resins. Many phase diagrams have been found and some of them have been analyzed on thermodynamic basis, and it became evident that the miscibility is a very important factor in PSA [H. J. Kin and H. Mizumachi]. In this presentation, I want to emphasize the fact that the adhesion performance is closely related to the structure/property of the adhesives.adhesives.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.30-37
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• 2005

To mass-produce useful biopolymer films, chitosan/gelatin blend films were prepared by solution casting method. Effects of mixing ratio, tensile strength (TS), elongation (E) at break, total color difference (${\Dalta}E$), opacity, water vapor permeability (WVP), oxygen permeability (OP), and thermal properties on chitosan/gelatin blend films properties were investigated. TS, E, ${\Dalta}E$, opacity, WVP, and OP values were 58.24-22.01 MPa, 13.11-24.67%, 1.86-17.45, 0.3104-1.2161 nmO.D./${\mu}m$, $1.6875-1.7225ng{\cdot}m/m^{2}{\cdot}s{\cdot}Pa$, and $2.2380{\times}10^{-7}-2.2975{\times}10^{-7}\;mL{\cdot}{\mu}m/m^{2}{\cdot}s{\cdot}Pa$, respectively. TS of blend films decreased, while E, ${\Dalta}E$, and opacity increased with increasing chitosan content. WVP of blend films did not show any significant relationship with mixing ratio and thickness of blend films. Miscibility of films was examined over entire composition range by thermogravimetric analyzer (TGA) and dynamic mechanical analyzer (DMA). TGA results showed gelatin is more thermally stable than chitosan and some interactions among functional groups of two biopolymers. Glass transition temperature $(T_{2})$ of films as determined by DMA decreased with increasing content of chitosan in the blend. Results of thermal analysis indicate high miscibility among polymer components in the blend.

• The Journal of the Petrological Society of Korea
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• v.1 no.2
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• pp.104-123
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• 1992

We present petrography, mineral chemistry of amphibole and plagioclase, and major and trace element chemistry for the Ogcheon metabasites occurring in the Poun and Mungyong areas to understand metamorphism, and to define chemical characteristics of parental rocks and their implication for tectonic environment. The Ogcheon metabasites often preserve relict igneous textures, although no primary phases are observed. They are mainly composed of amphibole (actinolite+hornblende)+plagioclase+epidote+chlorite+sphene+opaque oxides, indicating epidote amphibolite facies metamorphism. Coarse-grained amphiboles frequently have actinolitic composition in the core, and hornblende along the margin and cleavage, which can be interpreted either as miscibility gap or as result of polymetamorphism. Although presumed polymetamorphic events in the Ogcheon supergroup favor the latter possibility, further metamorphic studies are necessary to solve the problem. Amphibole and plagioclase chemistries suggest greenschist (epidote-amphibolite, if miscibility gap is present) to amphibolite facies metamorphism of possibly medium pressure. The major and trace element data of whole rocks indicate that the Ogcheon metabasites are transitional to tholeiitic basalts belonging to within-plate environment. Absence of evidences indicating deep sea environment suggests that the Ogcheon metabasites emplaced in an intra-cratonic, possibly rift environment which failed to proceed to an oceanic rift. Chemical variation of the metabasites toward a granitic pluton indicates K loss closer to the pluton, suggesting that caution should be taken when K is involved in a discussion.

• Membrane Journal
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• v.31 no.2
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• pp.153-159
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• 2021

In recent years, polymer membranes, which are actively used in various industrial fields, have the advantage of being able to impart unique properties through the control of chemical structures and physical properties in the film-fabrication process, as well as through fabricating blend membranes mixed with various materials. In this study, the solubility parameter, which can be used as an index of miscibility with other materials, was calculated using molecular dynamics using a silkworm (Bombyx mori) silk polymer which has a wide potential to be used as an eco-friendly natural material. When the solubility parameter of polyvinylalcohol (PVA), which is also environmentally friendly and biocompatible, was calculated by molecular dynamics and compared with each other, it was confirmed that the two polymer materials had similar solubility parameter values. In conclusion, it was theoretically proved that the two polymers could blend well with each other, which was confirmed through experiments.

• Macromolecular Research
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• v.9 no.4
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• pp.238-246
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• 2001

Properties of ternary blends of nylon 6 (Ny6), a thermotropic liquid crystalline polymer (TLCP, poly(ester amide), 20 wt%) and a maleic anhydride grafted polypropylene (2 wt%) (MAPP) were studied under various processing conditions. TLCP was pre-blended with MAPP first and then the binary one blended again with Ny6. The processing temperature of the second mixing was varied. Thermal properties show the partial miscibility of the ternary blend. The morphology of the TLCP phase in the first blending shows mostly in the fibril bundle shape, but varies between droplets and oriented fibrils after the second processing. Some of TLCP phase lost the fibril morphology during the second processing stage. The morphology variation invokes the change in tensile properties. Low extrusion temperature (270$\^{C}$) provides more fibril shapes, which are associated with less deformation in the second stage. The processing temperature effect was more evident when the draw ratio was high. High drawing was applicable due to the stabilizing action of tile compatibilizer.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.1
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• pp.59-69
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• 2000

The characteristics of liquid crystal polymer composite(LCPC) films are possessed of large-area and flexible display, polarizer free, high contrast, wide angle of visual filed and high responsiveness. It is well known that the LCPC films consisting of a continuous LC phase embeded in a three-dimentional network of polymer matrix are formed by photopolymerization-induced phase separation. In this study, we have investigated the point that both liquid crystals and polymer having different properties have to coexiste as composed films. The purpose of this study has been the development of new application with liquid crystals and UV-curable monomers. In the results abtained on the miscibility of nematic liquid crystal and UV-curable resins, difunctional monomer HX-620 turned out to shows the best. From the results abtained on structures, electro-optical properties and dynamic visocoelasticity for LCPC films, the best mixing ratio of monomer to LC mixture were 3/7(photoinitiator; 4wt%) by weight, and this ratio has been provided the most thermal stability for LCPC films. In the results abtained on structure and discoloration properties of LCPC films, it has been demonstrated that consiste of a 8:2 mixture of chiral nematic liquid crystal and HX-620 has the greatest domain and it was the best discoloration.

• Polymer(Korea)
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• v.39 no.3
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• pp.475-479
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• 2015

Droplet distribution of LCP(Vectra 950) and PET blend by repeated extrusion was examined through morphology analysis. Repeated extrusion was respectively proceeded twice and three times with blending condition and droplet distribution of only once extrusion sample showed uniform shape. However, droplet size of twice and three times extrusion samples increased and it was confirmed that droplets were concentrated on the center of specimens. It is thought that this phenomena were due to the compatibility and viscoelastic behavior of LCP/PET blend. Finally, it is thought that fiber manufacturing of different diameter is possible from spinning of repeated extrusion LCP/PET blended chip under same spinning condition.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.41.2-41.2
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• 2009

Electrospinning of Polyvinylalcohol (PVA), Gelatin (GE), and PVA/GE blend solutions in acetic acid were investigated to fabricate biodegradable for tissue engineering. The morphology of the electrospun nanofibers was investigated with a field emission scanning electron microscope. The fibers have average diameters in the range 50-150 nm. The miscibility of PVA/GE blend fibers was examined by differential scanning calorimetry.The PVA and GE were immiscible in the as-spun nanofibrous structure. X-ray diffraction (XRD) determined the crystallinity of the membrane and tensile strength for evaluation physical properties. An in vitro study of PVA/GE blend nanofibers was conducted. To assay the cytocompatibility and cell behavior on the PVA/GE blend nanofibrous scaffolds, cell attachment and spreading of fibroblasts seeded on the scaffolds were studied. Our results indicate that thePVA/GE blend nanofibrous matrix, particularly the one that contained 20% PVA and 80% GE could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for fibroblast cell.

• Polymer(Korea)
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• v.24 no.4
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• pp.477-487
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• 2000

A series of poly(L-lactic acid) (PLLA)/poly($\beta$-hydroxynonanoate) (PHN) blend were prepared to study the miscibility and the crystallization behaviors. The thermal behaviors and characterization of PLLA/PHN blends Were studied using differential scanning calorimetry (DSC), XRD and polarizing optical microscopy (POM). The PLLA and PHN are partially miscible in amorphous region. The crystallinity of PLLA increased as the content of PHN increased, and T$_{g}$, T$_{c}$, and T$_{m}$ of PLLA shift as the content of PHN increased. Moreover, the number of PLLA spherulite increased as the content of PHN increased in the POM experiment. Thus, PHN acted as a nucleating agent to PLLA.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.979-984
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• 1998

The conducting composites were prepared by blending of polyaniline(PANI) as conducting polymer and nylon6,6 as matrix in m-cresol. The PANI was protonated with alkylbenzenesulfonic acid such as camphorsulfonic acid(CSA) or dodecylbenzenesulfonic acid(DBSA). The miscibility of the composites was improved and the electrical conductivity was increased by adding dioctylphthalate(DOP). The electrical conductivity of the composites depending on the amount of protonating agent and PANI complex and the morphology were investigated. When it was protonated with DBSA having long alkyl chain and the content of PANI complex was 25 wt%, the electrical conductivity of the compsosite was increased up to 1.02 S/cm.