• Polymer(Korea)
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• v.38 no.3
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• pp.371-377
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• 2014

The effect of modification conditions on the physical properties of polydimethyl siloxane modified epoxy (PDMSME) was investigated. The number of ring opened epoxy attached to polydimethylsiloxane (PDMS) by silane coupling agent affected the physical properties of undercoating materials. The flexibility of thin coating was enhanced by PDMSME and the increase of ring opened epoxy attached to PDMS resulted in the increase of hardness by the crosslinking in the present with moisture. The higher molecular weight of PDMS caused the lowering of hardness while the surface contact angle increased due to the high silicone content in PDMS. The viscosity of silicone modified epoxy coating materials decreased with increasing of molecular weight of PDMS due to the lowering of entanglement of PDMSME molecules by acetone solvent and consequently, the smooth undercoated surface was obtained.

• Resources Recycling
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• v.13 no.3
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• pp.37-42
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• 2004

PVC powder was dehydrochlorinated by hydrothermal reaction at reaction time 0∼5 hr, reaction temperature $200∼250^{\circ}C$ in 0∼2M NaOH solution, and shape and structure of the PVC residue was investigated. The shape of the residue was changed largely according to NaOH concentration. Most of the residue was cohered in the aqueous solution, and many pores less than 10 $\mu\textrm{m}$ were formed on the surface. Dense network structure was well developed inside the residue. On the other hand, the residue in the NaOH solution was not cohered and its shape is roughly spherical. In the IR spectrum of the residue both in water and NaOH solution at $250^{\circ}C$, aromatic rings and absorption peak by C=C double bond were observed. From the results, it was observed that aromatic circle reaction and bridge reaction occured inter and intra molecules.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.54-60
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• 2004

This study deals with the setting behavior of polystyrene mortars using waste expanded polystyrene(EPS) solution-based binders. The binders for polystyrene mortars are made by mixing crosslinking agent with EPS solutions prepared by dissolving EPS in styrene. Polystyrene mortars are prepared with various EPS concentrations of EPS solutions and crosslinking agent contents, subjected to a dry curing, and tested for working life, peak exotherm temperature and 10h-length change. From the test results, He working lives of polystyrene mortars are shortened with raising EPS concentration of EPS solution and crosslinking agent content. Low-shrinkage or non-shrinkage polystyrene mortars could be obtained by adjusting EPS concentration of EPS solution and crosslinking agent content.

• Polymer(Korea)
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• v.30 no.5
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• pp.373-379
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• 2006

Polymerizable discotic liquid crystals containing diacetylene and acryloyl groups were formed through hydrogen bonding between phloroglucinol core and polymerizable pyridine derivatives, and their photopolymerization behavior was investigated. The discotic complexes exhibited discotic columnar and rectangular columnar mesophases depending on the number of aromatic rings. Photopolymerization of the discotic complexes was carried out by UV irradiation in the liquid crystalline state. IR and UV-Vis spectroscopy affirmed that diacetylene and acryloyl groups were selectively Polymerized, and that crosslinked polymers containing short conjugated diacetylene oligomers were produced by 1,4-addition. X-ray diffraction experiment showed that the columnar order in the discotic complex containing phenyl-pyridine moiety was maintained after photopolymerization, and that the rectangular columnar order in he discotic Complex with biphenyl units was changed to the lamellar order.

• Elastomers and Composites
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• v.44 no.1
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• pp.63-68
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• 2009

Recently, much attention has focused on the permanent deformation of roads in hot summer and cracks in cold winter, which are detrimental to safe driving. This leads to necessity of modification of asphalt to resist those deformation. In this study, a type of modified asphalt was prepared by addition of a photoinitiator which is activated by ultraviolet lay. The mechanical and rheololgical properties of photoinitiator-modified asphalt were examined using UTM and rheometer. Results showed that the modified asphalt was effected by ultraviolet and thus tensile strength and storage modulus increased, due to molecular attraction, with initiator content and irradiation dose. Thermal analysis showed less weight loss upon photoinitiator-modification and this indicated that the molecular attraction is the result of cross linking reaction between asphalt molecules induced by photoinitiator. According to long term ultraviolet curing test, properties of the photoinitiator-modified asphalt did not decrease or even increase for 20 years. This indicates that useful life of the asphalt could be extended by addition of photoinitiator.

• KSBB Journal
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• v.21 no.5
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• pp.401-404
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• 2006

Macroporous Poly(Methacrylic acid-co-Ethylene Glycol Dimethacrylate) Rods were in situ thermal initialized within a empty column($3.9{\times}150mm$) by free radical polymerization. The polymerization mixture was consisted of monomer, cross-linking monomer, porogenic solvent, initiator and control the ratio of these materials, column efficiency could be developed. Caffeine and tryptophan as separation substances and the retention mechanism of this kind of monolithic column was mainly hydrogen bond function.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.14-21
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• 2000

This paper presents the results of performance evaluation of silicone treatment technique which was developed for the insulation rehabilitation of water tree aged XLPE power cables. We treated the water tree aged 325 [$\textrm{mm}^2$] CN/CV cables with silicone, and then analyzed the degree of insulation rehabilitation as a function of time. AC breakdown test was conducted to evaluate insulation rehabilitation. The diagnosis test using relaxation current measurement and the characteristic analysis of insulation were also performed to estimate silicone treated cable. AC breakdown strength of silicone treated cable for one year was increased, resulting from the chemical reaction between silicone fluid and water. This experiment showed that the silicone treatment technique was effective for insulation rehabilitation of the water tree aged cables.

• Composites Research
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• v.15 no.2
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• pp.40-47
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• 2002

The di-functional epoxy resins, i.e., diglycidylether of bisphenol A(DGEBA) and diglycidylethere of bisphenol F(DGEBF) were initiated by cationic catalyst, i.e., benzylquinoxalinium hexafluoroantimonate(BQH) using electron-beam(EB) technique. And the effect of structure of DGEBA and DGEBF on thermal stabilities and cure behaviors was investigated. According to the experimental results, the decomposed activation energy based on Horowitz-Metzger method was higher in the case of DGEBA, but intergral procedural decomposition temperature(IPDT) of DGEBA was lower than DGEBF. This could be interpreted in terms of high crosslink density resulted from hydroxyl bond of DGEBF backbone. It was confirmed in increasing the hydroxyl band at $7000\;cm^{-1}$ and $5235\;cm^{-1}$ using near-infrared spectroscopy(NIRS).

• Journal of the Korean Society of Safety
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• v.6 no.3
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• pp.27-34
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• 1991

This paper is for the properties of the oxidation-proof of the partially discharged and of the molecular motion on chlorinated PE Film. this paper also shows the properties of the molecular motion of the ${\gamma}$ ray irradiated PE Film. 1 In the surface of the PE Film enforce chlorination, C-Cl be distributed up to 10 $\mu$m deep. 2. In according to the development of the chlorination, the measure of crystalization decreased and cross link occured. 3. Chlorination PE Film control the oxidation on ozone to occuratlon by partial discharge and it lost bonding chlorine. 4. in according to chlorination, ${\gamma}$ absorption in motion of CH2 main chain of PE drcreased by chlorine stbstitution.

• Composites Research
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• v.30 no.3
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• pp.193-201
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• 2017

Molecular dynamics simulation and the Mori-Tanaka micromechanics study are performed to investigate the effect of the covalent grafting between CNT and polyester on the mechanical behavior and load transfer of nanocomposites. The transversely isotropic stress-strain curves are determined through the tension and shear simulations according to the covalent grafting. Also, isotropic properties of randomly dispersed nanocomposites are obtained by orientation averaging the transversely isotropic stiffness matrix. By addressing the grafting, the transverse Young's modulus and shear moduli of the nanocomposites are improved, while the longitudinal Young's modulus decreases due to the degradation of the grafted CNT.