• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.63-69
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• 2001

Holographic transmission gratings were performed by an Ar-laser( ${\lambda}$=514nm) intensity, the ratio fo LC contents to the surfactant. The addition of the surfactant to the LC and pre-polymer systems causes the droplet to maintain the ideal size at the high fraction(over 40wt%) of the LC contents that induce the films to be fabricated with high diffraction efficiency than that of no surfactant series. The image of these films was examined using a charge coupled device (CCD). We also studied the angular selectivity plots which support the important role in the multiplexer channel (MUX). Eventually, we showed the reconstructive optical image recorded in this transmission mode of HPDLCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.531-536
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• 2012

We herein present results of flat and uniform polymer-blended small molecular semiconductor thin films. Which were produced for organic thin film transistors (OTFTs), using a simple pre-metered horizontal dipping process. The organic semiconducting thin films were composed of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-PEN) composite blended with a polymer binder of poly(${\alpha}$-methylstyrene) (PaMS). We show that the pre-metered horizontal-dip-coating(H-dip-coating) process allowed the critical control of the thickness of the blended TIPS-PEN:PaMs thin film. The fabricated OTFTs using the TIPS-PEN:PaMs films exhibited maximum field-effect mobility of $0.22\;cm^2\;V^{-1}\;s^{-1}$. These results demonstrated that H-dip-coated TIPS-PEN:PaMS films show considerable promise for the production of reliable, reproducible, and high-performance OTFTs.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1527-1528
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• 2006

This paper presents short-circuit tests for polymer-housed distribution arrestors depends on standards. The compared standards are IEC 60694(2004) and IEEE C62.11 (2005). Major differences depends on standards are prefaulted(pre-failure) method by means of a fuse wire and test procedure.

• Elastomers and Composites
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• v.46 no.3
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• pp.211-217
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• 2011

Wood Polymer Composite (WPC) has attracted a great deal of attention in environmental industries due to renewable resources, processability, excellent physical properties and logging regulations for application to housing units and engineering construction materials. In this study, commercial WPCs were prepared by using a modular intermeshing co-rotating twin screw extruder. The effect of three main factors such as wood flour contents, coupling agent concentrations and pre-treatment of wood flour on the properties of WPCs was extensively investigated. It was found that tensile strength and thermal stability were decreased with increasing wood flour contents whereas the water absorption was increased. Addition of maleic anhydride grafted polypropylene (PP-g-MA) into WPC exhibited better physical properties. On the contrary, the water absorption was slightly decreased with PP-g-MA. Finally the sample, which was prepared with pre-treated wood flour, represented the highest tensile strength. However, the water absorption of the sample was increased due to the transition of crystalline structure of cellulose.

• Macromolecular Research
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• v.17 no.10
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• pp.757-762
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• 2009

The micro domain structures and crystallization behavior of the binary blends of poly(methyl methacrylate)-b-poly(pentafluorostyrene)-b-poly(methyl methacrylate) (PMMA-PPFS-PMMA) triblock copolymer with a low molecular weight poly(vinylidene fluoride) (PVDF) were investigated by small-angle X-ray scattering (SAXS), small-angle light scattering (SALS), transmission electron microscopy (TEM), optical microscopy, and differential scanning calorimetry (DSC). A symmetric, PMMA-PPFS-PMMA triblock copolymer with a PPFS weight fraction of 33% was blended with PVDF in N,N-dimethylacetamide (DMAc). In the wide range of PVDF concentration between 10.0 and 30.0 wt%, PVDF was completely incorporated within the PMMA micro domains of PMMA-PPFS-PMMA without further phase separation on a micrometer scale. The addition of PVDF altered the phase morphology of PMMA-PPFS-PMMA from well-defined lamellar to disordered. The crystallization of PVDF significantly disturbed the domain structure of PMMA-PPFS-PMMA in the blends, resulting in a poorly-ordered morphology. PVDF displayed unique crystallization behavior as a result of the space constraints imposed by the domain structure of PMMA-PPFS-PMMA. The pre-existing microdomain structures restricted the lamellar orientation and favored a random arrangement of lamellar crystallites.

• Journal of the Korean Society of Visualization
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• v.5 no.1
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• pp.3-8
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• 2007

We present simple methods for fabricating high aspect-ratio polymer nanostructures on a solid substrate by rigiflex lithography with tailored capillarity and adhesive force. In the first method, a thin, thermoplastic polymer film was prepared by spin coating on a substrate and the temperature was raised above the polymer's glass transition temperature ($T_g$) while in conformal contact with a poly(urethane acrylate) (PUA) mold having nano-cavities. Consequently, capillarity forces the polymer film to rise into the void space of the mold, resulting in nanostructures with an aspect ratio of ${\sim}4$. In the second method, very high aspect-ratio (>20) nanohairs were fabricated by elongating the pre-formed nanostructures upon removal of the mold with the aid of tailored capillarity and adhesive force at the mold/polymer interface. Finally, these two methods were further used to fabricate micro/nano hierarchical structures by sequential application of the molding process for mimicking nature's functional surfaces such as a lotus leaf and gecko foot hairs.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.321-325
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• 1997

Recently, photosensitive color filters have received much attention for their use in the liquid crystal display (LCD) industry. It is well known that chemical and physical properties of polymer surfaces can be modified by special surface treatments. In this work, we have studied the polymer surfaces of LCD blue color filters which were exposed to the UV light during photolithography. A better understanding of the irradiated polymer surfaces is required for the subsequent processes such as plasma etching, ITO electrode deposition, etc. The surface analysis has been undertaken using secondary ion mass spectrometry (SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). A significant enrichment of the pigment component and roughening of surface with bubble-like feature have been observed at the modified polymer surface.

• Macromolecular Research
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• v.10 no.4
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• pp.221-229
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• 2002

PET nanocomposites filled with fumed silicas were prepared via direct melt compounding method at various mixing conditions such as filler type and filler content. Some fumed silicas were pre-treated to improve the wettability and dispersibility, and principal characterizations were performed to investigate the effects of nano fumed silicas on polymer matrix. Hydrophobic fumed silica (M-FS), which has the similar contact angles of water with neat PET, acted as the best reinforcement for the thermal stability and mechanical properties of PET nanocomposite, and FE-SEM images also showed that M-FS was uniformly dispersed into matrix and had good wettability. But, some filler (O-FS) had low dispersibility and caused the deterioration of mechanical properties. Besides, the results of DSC revealed the nucleation effect of all fillers in polymer matrix, and PET nanocomposite filled with hydroptilic fumed silica (FS) showed markedly the characteristic dynamic rheological properties such as shear thinning behavior at very low frequencies and the decrease of viscosity.

• Macromolecular Research
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• v.10 no.6
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• pp.311-317
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• 2002

The quantitative analysis of polymer micelles consisting of amphiphilic block copolymers was carried out by small-angle neutron scattering (SANS). The block copolymers, made of poly(2-ethoxyethyl vinyl ether-b-2-hydroxyethyl vinyl ether)(poly(EOVE-b-HOVE)), exhibited a sharp morphological transition from a homogeneous solution to a micelle structure with increasing temperature. This transition is accompanied by a formation of spherical domains of poly(EOVE) with a radius around 200 $\AA$. The variations of the size and its distribution of the domains were investigated as a function of polymer concentration and temperature. The validity of SANS analysis, including the wavelength- and incident-beam-smearing effects of the SANS instrument, was examined with a pre-calibrated polystyrene latex.

• Elastomers and Composites
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• v.51 no.4
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• pp.342-349
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• 2016

Characteristics of the swelling-induced wrinkles on the surfaces of natural rubber (NR) film were investigated. The wrinkle structure was generated by swelling of NR film pre-stretched and firmly bonded onto an aluminum substrate in hexane. A novel experimental method was adopted to replicate the swelling-induced wrinkles on the NR film using an epoxy-hardener system. To get insight into the wrinkle parameters; the wrinkle length (L), wrinkle distance (D), wrinkle height (H) and the angle between two consecutive wrinkles (${\theta}$), the cross-sections of the replicas obtained from saturated swollen NR film were examined using an optical microscopy (OM). From the OM images, the wrinkling parameters were measured as a function of the thickness of NR film from 0.42 to 1.76 mm. Also, it was evaluated that the effects of swelling time on the wrinkling parameters. The length (L), distance (D) and height (H) of wrinkles increased as the thickness of the NR film and the swelling time increased. However, the angle between the wrinkles (${\theta}$) showed a sharp decrease up to a swelling time of 200 minutes and slightly decreased afterwards.