Papers by Hyung-Joong Kim
Polymer Korea, 2013
Surface properties such as morphology, crystalline structure, and chemical composition of poly(vi... more Surface properties such as morphology, crystalline structure, and chemical composition of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend coatings prepared by dispersion coating on poly(ethylene terephthalate) (PET) film have been investigated. It was observed that the surface properties were greatly influenced by the coating temperature and blend composition according to SEM, ATR-FTIR and XPS analysis. The typical surface morphology of α-crystalline structure of PVDF could be observed when the coating temperature was lower than 120 o C or the amount of PVDF was higher than 80 wt% in the blend. Otherwise, the crystalline structure was changed from α-crys- tal to γ-crystal or amorphous state. Based on the XPS analysis, the surface segregation of PVDF chains in the blend coating was confirmed.
Hybrid emulsions consisting of polyurethane and acrylic polymer were prepared by emulsion polymer... more Hybrid emulsions consisting of polyurethane and acrylic polymer were prepared by emulsion polymerization of acrylic monomers and polyurethane water dispersions (PUD) as an emulsifier. At first, cationic type of PUD was synthesized with IPDI, PTMG1000, MDEA, and acetic acid. Then, acrylic monomers, such as MMA and n-BA, were copolymerized with the PUD without adding further surfactant. The tensile properties and water resistance increased with increasing acrylic monomer ratio. The hybrid emulsions showed better properties than the emulsions simply blended with the PUD and the acrylic emulsions.
Journal of Applied Polymer Science, 2003
A polystyrene (PS)/poly(butyl acrylate) (PBA) composite emulsion was produced by seeded emulsion ... more A polystyrene (PS)/poly(butyl acrylate) (PBA) composite emulsion was produced by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles which were prepared by emulsifier‐free polymerization of styrene with potassium persulfate (KPS) under a nitrogen atmosphere at 70°C for 24 h with stirring at 60 rpm and swelled with the BA monomer in an ethanol/water medium. The structure of the PS/PBA composite particles was confirmed by the presence of the characteristic absorption band attributed to PS and PBA from FTIR spectra. The particles for pure PS and PS/PBA with a low content of the BA monomer were almost spherical and regular. As the BA monomer content was increased, the particle size of the PS/PBA composite particles became larger, and more golf ball‐like particles were produced. The surface morphology of the PS/PBA composite particles was investigated by AFM and SEM. The Tg's attributed to PS and PBA in the PS/PBA composite particles were found at 110 and −49...
Journal of Macromolecular Science, Part A, 1996
Abstract Radical polymerization of methyl methacrylate (MMA) in the presence of propylbenzene, be... more Abstract Radical polymerization of methyl methacrylate (MMA) in the presence of propylbenzene, benzonitrile, their equimolar mixture, and a mixture of nematic liquid crystals (LC) was studied. Chain transfer reaction and unexpected dependence of the initial polymerization rate on LC concentration were revealed by means of UV spectrophotometry, viscometry, and dilatometry. The chain transfer reaction which occurred at the boundary of LC domains in the polymer matrix caused binding of some of the LC molecules to the macromolecules of PMMA. An increase in the initial rate of polymerization and a decrease of polydispersity were explained with formation of the LC phase because growth of the macroradicals continued not only in the homogeneous polymer phase but simultaneously also at the interfacial boundary between the polymer matrix and the LC phase. It is assumed that the LC molecules anchored to the PMMA matrix can affect the mobility of free LC molecules in the LC domains when an external electric field is ...
Polymer Korea, 2012
초록: 열적으로 안정한 탄화수소계 액상 파라핀인 YK-D130을 분산매로 사용하여 ω-amino carboxylic acid와 adipic aicd로부터 폴리아미드 12(PA... more 초록: 열적으로 안정한 탄화수소계 액상 파라핀인 YK-D130을 분산매로 사용하여 ω-amino carboxylic acid와 adipic aicd로부터 폴리아미드 12(PA12) 올리고머(oPA1)를 제조하였으며 이들을 통상의 벌크중합으로 제조되는 비 슷한 분자량의 폴리아미드 올리고머(oPA2)로 합성하여 분자량과 기타 특성을 비교하였다. 색도 분석 결과 oPA1이 더 밝은 백색을 나타냈고, GPC 결과로부터 oPA1가 더 좁은 분자량 분포를 보였다. 나아가 oPA1과 oPA2를 hard segment로 하고 poly(tetramethylene glycol)(PTMG)을 soft segment로 하는 탄성의 poly(ether-block-amide)(PEBA)를 합성하였다. 합성된 PEBA의 분자량과 기계적 성질 등을 비교 분석하였다.
After pressurized impregnation treatment, which has been proposed as an effective conservation me... more After pressurized impregnation treatment, which has been proposed as an effective conservation method for stone cultural property, was executed with methyl metacrylate (MMA), MMA-butyl acrylate (PMB73) mixture and MMA-vinyl trimethoxy silane (PMV5) co-monomer mixture, the physical-chemical properties on the sand stone and the granite impregnated were evaluated. Compared to the case of granite, the impregnation ratios of sand stone showed larger values in the range of 3.2 to 3.7 wt% and these were increased up to 32% when the decompression process was applied to autoclave. The physical properties of sand stone such as anti-moisture property, flexural strength, impact property and ultrasonic velocity were also higher values than those of granite, which can be interpreted by high impregnation ratio resulted in many void within sand stone. The impact failure energy was 1.22 J for PMMA, 1.84 J for PMB73, and 2.8 J for PMV5, respectively. Since the inorganic affinity of treatment agent is more effective than the molecular structure of acrylic agent, PMV5 improved inorganic property indicates the optimum impact property.
Journal of Applied Polymer Science, 2012
A functionalized fumed silica was dispersed in water using a nonionic surfactant, yielding a stab... more A functionalized fumed silica was dispersed in water using a nonionic surfactant, yielding a stable nanodispersion. This was blended with an aqueous acrylic polymer dispersion to produce hybrid nanocomposite films. The silica particles were shown to be well dispersed in the polymer matrix, with little agglomeration. Further evidence of good compatibility between the silica and acrylic polymer was given by the improved thermal stability of the nanocomposite compared with the pristine polymer. The nanocomposite films exhibited significantly lower dirt pickup behavior, which seems to be associated to the nanoroughness of the composite film surface observed in AFM analysis. This decreases the contact area between film and micrometric dirt particles. Surface tension and hardness do not seem to be significantly different in the composite and noncomposite materials. This approach may provide a strategy to obtain hybrid coatings with self-cleaning properties, taking advantage of the relatively low cost, and large availability of fumed silica. V
Polymer Korea, 2013
Commercially available polyamide thermoplastic elastomer (PA-TPE) was blended with hybrid filler ... more Commercially available polyamide thermoplastic elastomer (PA-TPE) was blended with hybrid filler which was prepared by means of the reaction between polyhedral oligomeric silsesquioxane (POSS) containing amine group and toluene diisocyanate (TDI)-caprolactam (CL) to explore the effect of blending the hybrid filler with the TPE. The chemical structure of the filler was identified by using FTIR and 1 H NMR. The composites, PA-TPE/POSS-(TDI+CL), which were the blends of TDI+CL modified POSS filler and PA-TPE up to 7 wt%, showed better elastic recovery delivered from lower tension setting compared to the PA-TPE and the PA-TPE/octaphenyl POSS blend. In addition the tensile strength and the initial modulus increased with increasing the hybrid filled content. Consequently it was assumed that the POSS-(TDI+CL) filler was a suitable material for enhancing strength and modulus without loss of elastic properties for the original PA-TPE.
Journal of Colloid and Interface Science, 1997
refractive indices between LC and polymer matrix is the A mixture of nematic liquid crystals, E-7... more refractive indices between LC and polymer matrix is the A mixture of nematic liquid crystals, E-7, was dispersed by main reason for opaqueness. using several water soluble acrylamide copolymers. The copoly-In dispersion technology how to regulate the size and mers were synthesized by copolymerization of acrylamide with stabilize the dispersion droplets are so important that the hydrophobic monomers such as styrene and methyl methacryproperties of the film formed will depend on those paramelate. The steric stabilization of the liquid crystal-in-water disperters (5). The dispersion of LC in the medium of water sion was achieved by these copolymers. It was found that prefersoluble polymer solution has not been studied widely. Howential adsorption hydrophobic moieties onto the liquid crystal droplet surface resulted in steric stabilization of the dispersion. ever, this issue still remains interesting both from theoretical This stable liquid crystal-in-water dispersion can be used to and practical viewpoints. On the other hand, the application fabricate nematic curvilinear aligned phase from aqueous polyof water soluble polymers containing hydrophobic chains to mer systems. ᭧ 1997 Academic Press increase the dispersion stability of nonordered low molecular Key Words: acrylamide copolymers; liquid crystal; steric stabiliweight oil-in-water systems has been vastly explored by zation; adsorption; dispersion stability. some scientists (6, 7). Unlike usual oil-in-water dispersion, the dispersion of nematic LC would be more complicated because of LC's ordered structure and relatively high viscos-94
Journal of Applied Polymer Science, 2009
Copolymers of butyl acrylate (BA)-methyl methacrylate (MMA)-acrylic acid (AA) and intraparticle c... more Copolymers of butyl acrylate (BA)-methyl methacrylate (MMA)-acrylic acid (AA) and intraparticle crosslinking agents containing N-methylol acrylamide (NMA) and ethylene glycol dimethacrylate (EGDMA) were prepared by emulsion copolymerization. After that, films were prepared from the mixture of copolymers and the interparticle crosslinking agents. The interparticle crosslinking agents were prepared from hexamethylene diisocyanate and aziridine ethanol. Mixtures of the copolymer and the interparticle crosslinking agent were cast to films and crosslinked in a convection oven. The effects of the contents of the intra/interparticle crosslinking agents were also evaluated. By increasing the contents of EGDMA, roughness of the films was increased because of the effects of EGDMA acting as an intraparticle crosslinking agent. By increasing the contents of the interparticle crosslinking agent, roughness was also increased by the reaction between the copolymers and interparticle crosslinking agent. Tensile strength and water and chemical resistance of the film were increased, whereas elongation of film was decreased by increasing the contents of interparticle crosslinking agents. V
Journal of Membrane Science, 2012
Novel sulfonated poly(arylene ether sulfone) copolymers containing intermolecular ionic cross-lin... more Novel sulfonated poly(arylene ether sulfone) copolymers containing intermolecular ionic cross-linkable moieties, 5,5-bis[2,4-(hydroxyphenyl) benzimidazole] (BHPB), are synthesized by direct polymerization for application in polymer electrolyte membranes in DMFCs. The synthesized copolymers are controlled by various monomer compositions to confirm the effects of ionic cross-linking from sulfone-amine groups and degree of sulfonation on the polymer electrolyte membrane. The mechanical and thermal properties are enhanced in the ionic cross-linked membranes compared to the non-ionic cross-linked membrane. The water uptake and methanol permeability descend with decreasing degree of sulfonation and increasing content of BHPB. Similarly, regarding proton conductivity and ion exchange capacity (IEC), the low sulfonated membrane with high content of BHPB displays low values. This is attributed to the formation of ionic bonding by the sulfonic acid and amine groups. The novel polymer in this study shows very promising performance in direct methanol fuel cells which is comparable to that using Nafion 115.
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Papers by Hyung-Joong Kim