• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.105-108
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• 1996

We have studied the anisotropic dispersion force effects for surfaces alignment of liquid crystals (LCs) on rubbed polystyrene (PS) surfaces by unidirection. In microphotographs of the textures, we obtained the nematic (N) LCs are shown to align in both direction parallel and Perpendicular to the rubbing for region up to medium rubbing, however to align in the direction perpendicular to the rubbing for strong rubbing legion. We suggest that the anisotropic dispersion force is very important rather than macro-surface groove effect to uniform alignment of LCs. We also measured the temperature dependence of extrapolation length of 5CB on rubbed PS surfaces for strong rubbing. It is shown that the polar anchoring strength of 5CB is very weak on rubbed PS surface compared to the rubbed polyimide (Pl) surface.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1457-1459
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• 2003

Space charge distributions and behaviors of polystyrene/polyaniline conducting blends were investigated using a pulsed electroacoustic(PEA) method. It was found that positive charges were accumulated near the cathode with increasing polyaniline content in polystyrene/polyaniline when electric field was applied. Breakdown phenomena was investigated by breakdown test and it was observed that dielectric strength was diminished as polyaniline content was increased. By Scanning Electron Microscopy, corss-sectional views of polystyrene/polyaniline conducting blends were observed that the particles of polyaniline were well distributed in polystyrene.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.923-928
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• 2012

Optimizing a water-phase suspending system is very important to manufacture high-quality suspension polymerized toners. Therefore, in this study, the effects of the molar ratio of calcium hydroxide ($CaOH_2$)/phosphoric acid ($H_3PO_4$)(Ca/P), which were used as inorganic suspending agents, and pH of the water-phase on the characteristics of styrene-based suspension polymerized toners were mainly investigated. At first, the water-phase was fixed to neutral condition (pH=7.5) and Ca/P molar ratio was changed from 1.5:1 to 1.76:1. As a result, an ideal calcium phosphate (hydroxyapatite) was prepared at the Ca/P molar ratio of 1.73:1 and polymerized toners prepared at this condition showed good particle size distribution, circularity and charging characteristic. Based on this result, Ca/P molar ratio was fixed to 1.73:1 and pH of the water-phase was changed to weak acidic (pH=5.5) and weak basic (pH=9.5) conditions. As a result, polymerized toners prepared under the weak acidic condition showed very good particle size distribution, circularity and charging characteristic along with excellent printing quality. High-quality suspension polymerized toners could be prepared via optimizing Ca/P molar ratio and pH of the water-phase.

• Journal of Sericultural and Entomological Science
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• v.27 no.1
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• pp.47-50
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• 1985

The physical properties of graft polymerized silk fibre were investigated with various vinyl monomers. 1. The graft polymerization of styrene and methyl methacrylate onto raw silk reduced the tenacity and elongation of raw silk due to fixation of sericin covering silk fibre in, but the styrene grafting was more effective for sericin fixation of raw silk than the methyl methacrylate one. 2. The water absorbability of glycidyl methacrylate grafted silk increased 14.6% greater than that of methyl methacrylate grafted silk at the same degree of grafting polymerization. 3. The degree of grafting polymerization was increased mostly with ethylene glycol methacrylate. The water absorbability of ethylene glycol methacrylate grafted silk was higher than that of glycidyl methacrylate or ethyl acrylate grafted silk. But the grafted silk fabric increased the fabric flexural rigidity which was negatively related with the favorability of fabric hand-touch, as compared with that of nongrafted silk fabric. 4. The evenness of graft polymerization could be improved by agitating the polymerization bath at the fixed interval by reducing the inter size deviation of grafted silk skein and the thickness deviation of grafted silk fabric.

• Polymer(Korea)
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• v.34 no.1
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• pp.20-24
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• 2010

In this study, ETFE-g-PSSA membranes with various degrees of grafting (DOG) and thicknesses were prepared by a simultaneous irradiation method. SEM-EDX instrument was applied to measure the relative distribution of sulfur which is corresponding to that of a grafted polymer over the Cross-section of the ETFE-g-PSSA membranes prepared at various irradiation conditions. The results indicate that to obtain the evenly-grafted membranes, a styrene/dichloromethane ratio is needed to be under 60 (v/v%), and a higher DOG is required as the film thickness increases. The effects of DOG and thickness on the ion exchanging capacity (IEC) and water uptake (WU) were investigated by measuring the IEC and WU values of the membranes with various DOG and thicknesses.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.676-685
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• 2016

This study investigated the conversion of oil products from polystyrene by using dispersed Co and Mo catalyst on reaction time and concentration change for knowledging on characteristics at low temperature (425, 450 and $475^{\circ}C$) pyrolysis and reaction time(20~80 min, 15 min interval) in a batch reactor. It will be showed the conditions for optimum pyrolysis at reaction temperature $450^{\circ}C$ and the reaction time 35min, and the main components of the converted liquid oil were styrene and benzene derivatives by GC/MS. The oil products formed during pyrolysis were classified into gas, gasoline, kero, diesel and heavy oil according to the domestic specification of petroleum products. The pyrolysis conversion rate was showed as Co catalyst > Mo catalyst > Thermal in all reaction time at reaction temperature $450^{\circ}C$. The yields rate of gas, kerosine, diesel were the most hight at Mo Catalyst, gasoline was at thermal and heavy oil was at Co catalyst. The conversion rate and yields of the pyrolysis products were the most height when Co catalyst ratio was 100%.

• Textile Coloration and Finishing
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• v.28 no.3
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• pp.164-174
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• 2016

In this study, dye-encapsulated microcapsules were produced by emulsion polymerization using styrene monomer. The study showed that the average size of microcapsules were $2{\sim}5{\mu}m$ in normal distribution. These microcapsules induced pale yellow(A12) and reddish yellow(B24) color by thermochromic fluoran yellow(dye A) and red(dye B). These microcapsules were changed to dark yellow(A12) and scarlet(B24) color depending on temperature change. The weight of microcapsules decreased by 7% to 11% during the heating ranges from $320^{\circ}C$ to $350^{\circ}C$ implying that the styrene microcapsules had thermal stability upto $300^{\circ}C$.

• Korean Journal of Materials Research
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• v.28 no.5
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• pp.279-285
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• 2018

Graphene is an interesting material because it has remarkable properties, such as high intrinsic carrier mobility, good thermal conductivity, large specific surface area, high transparency, and high Young's modulus values. It is produced by mechanical and chemical exfoliation, chemical vapor deposition (CVD), and epitaxial growth. In particular, large-area and uniform single- and few-layer growth of graphene is possible using transition metals via a thermal CVD process. In this study, we utilize polystyrene and boron oxide, which are a carbon precursor and a doping source, respectively, for synthesis of pristine graphene and boron doped graphene. We confirm the graphene grown by the polystyrene and the boron oxide by the optical microscope and the Raman spectra. Raman spectra of boron doped graphene is shifted to the right compared with pristine graphene and the crystal quality of boron doped graphene is recovered when the synthesis time is 15 min. Sheet resistance decreases from approximately $2000{\Omega}/sq$ to $300{\Omega}/sq$ with an increasing synthesis time for the boron doped graphene.

• The Korean Journal of Rheology
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• v.10 no.2
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• pp.74-81
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• 1998

사출성형품의 설계는 그 내부의 기계적 물성 변화보다는 전통적으로 용도에 부합하 는 형상을 위주로 하여 이루어져 왔기 때문에 설계조건의 개선을 통하여 성능이 우수한 제 품을 얻기까지 많은 시행착오가 요구되고 있다. 그런데 사출성형 실험이나 물성평가 시험을 하기 전에 성형품의 부위별 기계적 물성을 알수있다면 제품의 설계나 금형 설계에 많은 도 움이 될 수 있으므로 최근에 물성 예측을 위한 방법론들의 개발이 다양하게 시도되고 있다. 따라서 본 연구에서는 학습시스템, 사출성형 수치모사와 기계적 물성과의 상관관계를 밝히 는 방법을 만들어 사출물이 제작되기 전에 그들의 기계적 물성을 사출성형 수치모사에서 얻 어진 열적·기계적 이력으로부터 예측하고자 하였다. 이때 성형품의 기계적 물성과 열적· 기계적 이력 사이에는 매우 복잡하고 비선형적인 상관관계를 보이기 때문에 이들 사이를 비 매개변수적으로 연관짓기 위하여 역전파 인공신경망 알고리듬을 사용하였으며 열적·기계적 이력은 사출성형용 수치모사 소프트웨어를 이용하여 구하였다. 학습과정에서 전역최소값에 도달하지 못하는 인공신경망의 문제점을 해결하기 위하여 모멘텀변수와 잡음지수를 포함하 는 일련의 항을 첨가하여 연결가중치를 보정하였다. 그 결과 어떤 초기값에 의하여 학습이 되더라도 전역최소값에 도달하는 것을 확인하였으며 이를 이용하여 다른 사출조건에서 사출 물의 기계적 물성을 잘 예측할수 있었다.

• Journal of Radiation Industry
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• v.10 no.4
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• pp.167-171
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• 2016

The scintillation efficiency of the polystyrene based plastic scintillator depends on the ratio of the wavelength shifters, organic fluors(PPO and POPOP). Thus, 24 samples of the plastic scintillator were fabricated in order to find out the optimum ratio of the wavelength shifters in the plastic scintillator. The fabricated plastic scintillators were trimmed through a cutting and polishing process. They were used in gamma energy spectrum measurement with the $^{137}Cs$ emitting mono-energy photon with 662 keV for the comparison of the scintillation efficiency. As a result, it was found out that the scintillator sample with 1.00 g of PPO (2,5-Diphenyloxazole) and 0.50 g of POPOP (1,4-Bis(5-phnyl-2oxidazolyl)benzene) dissolved in 100 g of styrene solution has the optimum ratio in terms of the light yield of the polystyrene based plastic scintillator.