• Polymer(Korea)
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• v.25 no.6
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• pp.818-825
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• 2001

Polycarbonate(PC)/montmorillonite (MMT) nanocomposites were prepared by solution and melt mixing methods. A d-spacing of the nanocomposites was measured by an X-ray diffractometer. Neat montmorillonite (MMT-Na) and MMTs modified by dodecyl ammonium (MMT-DA) or dimethyl hydrogenated tallow 2-ethylhexyl ammonium (MMT-25A) were used. The d-spacing value of PC/MMT-25A and PC/MMT-DA was higher than that of PC/MMT-Na. The d-spacing increased from around 12 to $37AA$ depending on the mixing method. PC was more readily introduced to the gallery of MMT as the molecular weight of PC reduced and the mixing time increased. PC/MMT-25A showed higher thermal stability by thermogravimetric analysis (TGA) than PC/MMT-DA and PC/MMT-Na.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.1
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• pp.43-50
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• 2000

In this study, experiments were carried out to measure the variations in the corrosion potential and current density of polarization curves using polycarbonate. The results were particularly examined to identify the influences affecting the corrosion potential including various conditions such as temperature, pH, catalytic enzyme, and salt. The lines representing the active anodic dissolution were only slightly shifted in the potential direction by temperature, pH, enzyme, and salt. The tafel slope for the anodic dissolution was determined based on the polarization effect with various conditions. The slope of the polarization curves describing the active-to-passive transition region were noticeably shifted in direction. Also, from the variation in the conditions, the optimum conditions were established for the most rapid transformation, including temperature, pH, corrosion rate, and resistance of corrosion potential. The second anodic current density peak and maximum passive current density were designated as the critical corrosion sensitivity(Ir/If). The value of Ir/If was then used in measuring the extent of the critical corrosion sensitivity of the polycarbonate. The potentiodynamic parameters of the corrosion were obtained using a Tafel plot.

• Journal of Ocean Engineering and Technology
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• v.27 no.1
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• pp.109-114
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• 2013

Regulations on exhaust emissions for vehicles and ships are reinforced. Therefore, researchers are focus on developing an excellent engine that emits less environmental pollutants and leads to high gas milage. The purpose of this study is to investigate the efficiency of intake super charging system. Super charger is the special device for improving performance of intake system. Futhermore, for reducing exhaust emissions, the examine are performed on the effectiveness of device structures that tow materials for performance improvement. To fulfill the purpose, Super charger materials of aluminum alloy(AL6262) and polycarbonate were selected and then their temperature change of super charger and inhalation efficiency were analyzed by ANSYS program. In addition, it is attempted to apply these results to device development by comparing the results with the real value. As a result, there was less temperature change of super charger in aluminum materials than polycarbonate, and HC and NOx were decreased when the super charger was installed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.131-137
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• 2017

In this study, we evaluated the surface roughness of mold and injected parts manufactured by polycarbonate (PC) injection molding. The mold surface was polished to produce six differentiated roughnesses with 12 areas using stones (#800, #1200), sandpapers (#800, #1200), and diamond compounds (#8000, #14000). Injected parts were created using 20mm/s injection speed, 80 bar holding pressure for 5 seconds, and $70^{\circ}C$ cooling water. Injected parts surface roughness (Sa) was measured randomly in 10 of 30 using an interferometer (NewView8000, zygo, USA). In the same way, mold surface was measured randomly 10 times on 12 polished areas. Surface roughness of molds and injected parts were compared, and a regression equation to predict mold surface roughness was proposed for specific injection molding parameters.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.42-49
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• 2009

The optical elements made of plastics are normally produced by mass production such as injection molding with use of precision dies and molds. It costs to prepare the dies and molds, and it is only justified to prepare such expensive dies and molds when the parts are massively produced. On the other hand, it is too expensive and inefficient when precision plastic parts are needed only in small quantities, such as a case of trial manufacturing of new products. An ultra-precision diamond cutting is one of promising processes to produce the precision plastic parts in such cases. But it is commonly believed that an ultra-precision cutting of plastics for optical components is very difficult, because they are thermo-plastic material. In the present research, an ultra-precision diamond cutting of polycarbonate (PC), that is one of typical optical materials, was tried by using elliptical vibration cutting method. It is experimentally proved that good optical surfaces were obtained by using elliptical vibration cutting in cases of grooving and flat surfaces. The maximum surface roughness of less than 60 nm in peak to valley value is acquired.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.188-191
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• 2005

Two different coverlayers which is useful for an optical buffer and a mechanical protection made of not only UV resin but also polycarbonate coversheet were prepared on small form factor optical disks. Thin coverlayer of 10 ${\mu}m$ and thick coverlayer of 80 ${\mu}m$ were fabricated. 10 ${\mu}m$-thick coverlayer was coated using UV resin material by spin coating method for the flying optical head application. On the other hand, 80 ${\mu}m$-thick coverlayer using coversheet with the resin bonding material was prepared for the non-flying optical head application. Both cases, the thickness uniformity seem to be the primary prerequisite factor, and it was analyzed. Thickness of 10 ${\mu}m$-thick UV resin coverlayer could be controlled within ${\pm}0.2m$ range and 80 ${\mu}m$-thick coversheet could be controlled within ${\pm}3{\mu}m$ range. However, the yield of such thickness tolerance was not good. New design of metal housing holder and polycarbonate outer ring was adopted to diminish the ski-jump phenomenon. Specifically, the polycarbonate outer ring was very effective to reduce the ski-jump. However, it should be careful to maintain uniform edge between disk and ring for the perfect coverlayer.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.52-62
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• 1990

Cationic polycarbonate type polyurethane was prepared from the quaternization reaction of N-methyldiethanolamine(MDEA) in urethane backbone which was obtained from the reaction of polycarbonate polyol, MDI and MDEA(chain exetender). Tensile strength and modulus of the cationic urethane resins were increased sharply with increasing the ionic content in urethane backbone. But hydrolysis resistance was decreased with increasing ionic contents. The selectivity of the cationic polycabonate urethane membrane for water/ethanol separation by pervaporation was about 20. The carrier mediated transport mechanism was considered the most probable separation mechanism for these membranes.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.179-179
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• 2013

현재 자동차 분야에서 차량 경량화를 통해 연비 향상 및 에너지 효율 향상을 기대하고 있으며, 차량 경량화의 한 수단으로 자동차용 유리를 고강도 투명 플라스틱 소재인 PC (Polycarbonate)로 대체하고자 하는 연구가 활발히 이루어지고 있다. 그러나, PC의 낮은 내마모 특성과 자외선에 의한 열화 및 변색 현상은 해결하여야 할 중요한 문제점으로 지적되고 있다. 본 연구에서는, PC의 내마모 특성을 향상시키기 위하여 transmittance가 확보되고, 고경도 특성을 갖는 Al-Si-N 박막 증착에 대한 연구를 하였다. Al-Si-N 박막 증착을 위하여 ICP-assisted reactive magnetron sputtering 장비를 이용하였으며, 고경도 특성을 갖는 Al-Si-N 박막을 제조하였다. 분석 장비로는 박막의 chemical state와 crystallinity를 확인하기 위하여 XPS (X-ray Photoelectron Spectroscopy), AES (Auger electron spectrscopy)와 XRD (X-ray diffraction)를 이용하여 분석을 수행하였으며, Knoop ${\mu}$-hardness tester와 Pin-on-disk를 이용하여 경도 및 내마모 특성을 평가하였다. Al-Si-N 박막의 두께는 ~5,000 ${\AA}$을 증착하였으며, 가시광 영역에서 평균 92%의 transmittance를 나타내었다. 박막의 Si/(Al+Si) 비율에 따라 다른 경도 특성을 나타냈는데, Si/(Al+Si) 비율이 26~32% 부근에서 최대 31 GPa의 경도 값을 확인 할 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1542-1545
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• 2009

For the application of flexible substrate to future display and new transparent devices, indium tin oxide (ITO) thin film was formed on polycarbonate(PC) substrate at room temperature by in-line sputter system. During the ITO sputtering, Ar and $O_2$ reaction gas were fixed at a constant value and the process pressure was varied from 3 to 7 mtorr. From the electrical and the optical properties of sputtered ITO films, the sheet resistances of as-deposited ITO films varied with a different pressure and the optical transmittances of the ITO films at visible wavelength were maintained above 85%. The results are considered to be due to the saturation of $O_2$ atoms from reaction in ITO film.

• Elastomers and Composites
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• v.55 no.2
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• pp.114-119
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• 2020

The effect of a greenhouse-covering material on its indoor environment and on the characteristics of cherry tomatoes grown in it was investigated. The conventional polyethylene (PE) film on the greenhouse roof was replaced by a polycarbonate (PC) sheet, while maintaining the main structural frame intact. Color changes and the formation of water droplets on the PC surface were avoided by applying coextrusion and coating layers. When compared to the PE greenhouse, the PC greenhouse enabled increased light transmittance and thus a higher indoor temperature during both summer and winter. The thermal insulating property of the PC sheet effectively reduced the heating loss by approximately 55% during winter. The cherry tomatoes grown in the PC greenhouse exhibited superior fruit characteristics in terms of size, weight, and sugar content. The total amount of cherry tomatoes produced per unit area (1,000 ㎡) in the PC greenhouse was found to be greater by approximately 19% compared to that in the PE greenhouse.