• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.3
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• pp.114-119
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• 2005

We investigated compatibilizing effects of electrical properties such as charge distributions and electrical breakdown in blends of low density polyethylene (LDPE) / polystyrene (PS) with poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), the triblock copolymer. The blends with $70\;wt\%$ of LDPE and $30\;wt\%$ of PS were prepared through a melt blending in a batch type kneader at a temperature of $220^{\circ}C$ when the SEBS content increased up to $10\;wt\%$. Scanning electron microscopy (SEM) was investigated for observation of morphology of LDPE / PS blends increasing SEBS contents. The morphological observation showed that addition of SEBS results in the domain size reduction of the dispersed PS phase and a better interfacial adhesion between LDPE and PS phases. Measurements of space charge distributions for blends was carried out with pulsed electroacoustic (PEA) method. It was possible to observe that the amount of charge storage in the LDPE / PS blends decreased wiか increasing of SEBS content. The location of SEBS at a domain interface enables charges to move from one phase to the other via domain interface and results in a indicative decrease in the amount of space charge for the LDPE / PS blends with SEBS. Electrical breakdown strength of these blends was observed. It was found that the maximum breakdown strength of the blend was 51.55 kV/mm. These results were better than 38.38 kV/mm of LDPE used electrical insulator for cables and were caused by crystalinity of blends. Because the crystalinity of blends were lower than LDPE, electrical breakdown strength of LDPE / PS blends is higher than that of LDPE. We evaluated the possibility of these blends for insulating material substituted LDPE.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.614-619
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• 2015

A plasma surface modification of powders has been carried out in a circulating fluidized bed reactor under reduced pressure. Polystyrene (PS) particles treated by plasma are grafted with polyethylene glycol (PEG) on the surface. The virgin, plasma-treated and grafted powders were characterized by DPPH method, FTIR, SEM and contact angle meter. The plasma-treated PS powders have well formed peroxide on the surface, By PEG grafting polymerization, PEG is well grafted and dispersed on the surface of the plasma-treated PS powders. The PEG-g-PS particle was successfully synthesized using the plasma circulating fluidized bed reactor under reduced pressure.

• Polymer(Korea)
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• v.30 no.1
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• pp.50-55
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• 2006

When the monodisperse polystyrene(PS)/HDDA polymer particles were synthesized via one-step polymerization using polystyrene seed particles by dispersion polymerization, the effects of 1) the molecular weight of seed polymer particles, 2) the ratio of the absorbed HDDA to the seed polymer particles (swelling ratio) and 3) seeded polymerization rate on the surface morphology of PS/HDDA polymer particles were investigated. It was observed that the creation of the crater shaped defect on the surface of PS/HDDA polymer particles was irrespective of the molecular weight of seed polymer ant swelling ratio. But its surface morphology could be controlled by the change of the seeded polymerization rate.

• Korean Journal of Materials Research
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• v.20 no.10
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• pp.550-554
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• 2010

This work presents a fabrication procedure to make large-area, size-tunable, periodically different shape metal arrays using nanosphere lithography (NSL) combined with ashing and annealing. A polystyrene (PS, 580 ${\mu}m$) monolayer, which was used as a mask, was obtained with a mixed solution of PS in methanol by multi-step spin coating. The mask morphology was changed by oxygen RIE (Reactive Ion Etching) ashing and temperature processing by microwave heating. The Au or Pt deposition resulted in size tunable nano patterns with different morphologies such as hole and dots. These processes allow outstanding control of the size and morphology of the particles. Various sizes of hole patterns were obtained by reducing the size of the PS sphere through the ashing process, and by increasing the size of the PS sphere through annealing treatment, which resulted in tcontrolling the size of the metallic nanoparticles from 30 nm to 230 nm.

• Macromolecular Research
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• v.16 no.7
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• pp.637-643
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• 2008

A combination of magnetic and temperature-responsive properties in the same polymer composites is expected to increase their potential applications in the biomedical field. Accordingly, micron-sized magnetite/polystyrene/poly(2-dimethylaminoethyl methacrylate-ethyleneglycol dimethacrylate), which are abbreviated as $Fe_3O_4$/PS/P (DM-EGDM) composite polymer particles, were prepared by the seeded copolymerization of DM and EGDM in the presence of magnetite/polystyrene ($Fe_3O_4$/PS) particles. $Fe_3O_4$/PS/P(DM-EGDM) composite particles with magnetic properties showed a temperature-sensitive phase transition at approximately $31^{\circ}C$. The adsorption behavior of the low molecular weight emulsifiers and trypsin (TR) as biomolecules were examined on $Fe_3O_4$/PS/P(DM-EGDM) composite polymer particles at different temperatures. The native conformation of TR was followed by measuring the specific activity under various adsorption conditions. The activity of the adsorbed TR on composite polymer particles was higher than those of the tree TR and TR adsorbed on $Fe_3O_4$/PS particles.

• Korean journal of food and cookery science
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• v.12 no.4
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• pp.499-505
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• 1996

The facillities for Kimchi preservation were investigated in order to develop the taste, flavor and commercial quality of Kimchi during fermentation. Four kinds of facillities used for this experiment were PP(Polypropylene). PSC(Polypropylene+ceramic)and PPP was selected newly and laminated of three layers with PETG (Polyester G), PS (Polystyrene) and PETG. The change of total number of lactic acid Bacteria, pH, acidity, color, gas contents and free internal volume of package were measured for the Kimchi packaged by 4 facillities during 6 days fermentation at 15$^{\circ}C$. The total No. of lactic acid Bacteria within the Kimchi in the PPP facillity was more and remained longer time (120 hrs.) than other Kimchi in the PP, PS and PPC facillities. Also the pH of all Kimchi were decreased to pH 4 within 72 hrs. and the pH of Kimchi in the PPP facillity was kept as pH 4 for 120 hrs., so that was shown to be decreased more dully than others. In case of fimchi in the PPP facillity, the color was retained better, CO$_2$ contents was lower similar to PPC facillity, and swelling degree of free internal volume was higher than others. By the sensory evaluation, the Kimchi in the PPP facillity represented as better than others for color, flavor, texture and total preferences until 48 hrs. fermentation. And the PPP facillity is transparent, so these will be selected and confirmed more easily, also PPP facillity is so hard to endure the swelling pressure of internal gas. Therefore it is thought that the PPP facillity used as Kimchi package will be desirable for better taste, flavor, and commercial quality.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.386-399
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• 2023

Microplastics and nanoplastics (NMPs) are considered one of hazardous contaminants in marine ecosystems due to their toxic effects, such as reproduction disorder and oxidative stress, on marine organisms. Although water temperature is rising due to global climate change, little information on the toxicological interaction between NMPs and temperature is available. Therefore, in this study, we confirmed the toxicity of NMPs (polystyrene [PS] beads; 0.05- and 6-㎛) on brackish water fleas (Diaphanosoma celebensis) depending on increased temperature (30℃ and 35℃) at individual and molecular levels. In the chronic toxicity test, the group exposed to high temperatures showed an earlier first reproduction time compared to the normal temperatures group, but it was delayed by co-exposure to NMPs at 35℃. Notably, the total reproduction decreased significantly only after 0.05-㎛ PS beads exposure at 30℃. Interaction analysis showed that first reproduction time, modulation of the antioxidant-related gene (GSTS1), heat shock gene (Hsp70), and ecdysteroid pathway-related genes (EcR_A, EcR_B, and CYP314A1) were closely related to temperature and PS beads size. These results indicate that microplastics have size-dependent toxicity, and their toxicity can be enhanced at high temperatures. In addition, higher temperatures and PS beads exposure may have negative effects on reproduction. This study suggests that various factors such as water temperature should be considered when evaluating the toxicity of microplastics in marine ecosystems, and provides an understanding of the complex toxic interaction between water temperature and microplastics for marine zooplankton.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.172-176
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• 2003

In this paper, we studied the effects of mold temperature on the microstructure of injection molded parts. The weld line decreases in length and width as mold temperature increases. We investigated the dimensional stability of the parts made of two kinds of resin(polypropylene and polystyrene) by varying the mold temperature. As the mold temperature is high, both the shrinkage ratio and the thickness difference for the PS parts decreases. But the observation of PP parts shows a tendency to increase. The easiness of cavity filling and transcription of the mold texture is improved as the mold temperature is high.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1600-1602
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• 1996

We have investigated the anisotropic dispersion force effects for surfaces alignment of liquid crystals (LCs) on rubbed polystyrene (PS) surfaces by unidirection. In microphotographs an 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 region. 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 (PI) surface.

• 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.