• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.259-259
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• 2009

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, they are not suited to outdoor insulator by reason of being not good hydrophobic. RTV has a good property of hydrophobic and ATH has characteristic obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained nano size ATH coat on surface of engineering plastics. In this paper, it compares resistance tracking of the engineering plastic coated RTV with that of non-coated engineering plastic and ATH filled composites performed much better than non-filled composites.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.621-626
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• 2001

Microcellular foaming process was developed at MIT in 1980's to save a quantity of raw materials and improve mechanical properties. There are many process variables in appling microcellular foaming process to the conventional injection molding process. Of all process variables, part dimension control and shrinkage are the most influential on the post molded dimension. The post molding dimensional change of thermoplastic resins is important to tool designers for predicting the specific difference of molded part vs. actual mold cavity. Generally, articles injection molded are smaller in size than the cavity; hence, the term shrinkage factor is used to define the allowance a designer specifies. It is important to consider the factors that influence molded part dimension. According to ASTM Designation: D 955, shrinkage from mold dimensions of molded plastics was measured. In injection molding, the difference between the dimensions of the mold and of the molded article produced therein from a given material may vary according to the design and operation of the mold. In this paper, shrinkage data of molded plastic parts was obtained. It can be an important information for designing optimum mold system in a microcellular foaming injection molding process.

• 한국생산제조학회지
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• 제21권2호
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• pp.252-258
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• 2012

A study of terahertz waves was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The terahertz systems were consisted of time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both non-conducting polymeric composites and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. The CFRP (Carbon fiber reinforced plastics) laminates were utilized for confirming the experimentation in the terahertz NDE. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field direction of the terahertz waves and the intervening fiber directions. A refractive index (n) was defined as one of mechanical properties; so a method was obtained in order solve the "n" in the material with non-conductivity. The usefulness and limitations of terahertz radiation are investigated for the NDE of FRP composites.

• Elastomers and Composites
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• 제49권1호
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• pp.37-42
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• 2014

폴리케톤은 일산화탄소, 에틸렌, 프로필렌을 단량체로 중합되는 삼중공중합체 (terpolymer)로서 폴리아미드, 플리에스테르, 폴리카보네이트 등의 일반 엔지니어링 플라스틱 소재에 비해 원료 및 중합 공정비가 저렴한 소재이다. 또한 기계적 특성과 내열성, 내화학성, 연료투과성, 내마모성 등이 우수하여 기존 엔지니어링 플라스틱 소재를 대체할 수 있는 환경 친화적인 소재로 주목을 받고 있다. 본 연구에서는 폴리케톤의 내열성을 향상시키기 위해 탄성체(Ethylene propylene copolymer, Nitrile butadiene rubber, Ethylene acrylic rubber)를 배합하여 블렌드물을 제조하였고, 각 소재에 대하여 내열성, 내유성에 평가에 따른 특성을 분석하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.29-29
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• 2010

Engineering plastics have excellent electrical properties, mechanical strength and various characteristic which include chemical resistance, environmental resistance, weatherability at a wide temperature range. It has good characteristic(light weight, good productivity) as compare with epoxy or porcelain insulators. However, engineering plastics not suited to outdoor insulator because it isn't hydrophobic. Therefore, to over come these critical problems, we improve the surface insulation characteristics of engineering plastic by coating micro-, nano- size inorganic fillers added to RTV-SIR(Room temperature vulcanized-silicone rubber) at this plastic surface. The effect is analyzed through salt-fog test, tracking test. In conclusion, the engineering plastic coated RTV with micro-$Al_2O_3$20[phr], nano-Al(OH)3 1 ~ 3[phr] improved much better than the others.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.29-29
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• 2010

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, it isn't suited to outdoor insulator because it is not hydrophobic. RTV(Room temperature vulcanizing) has a good property of hydrophobic and micro-filler. nano-filler have characteristics of obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained with micro, nano-filler coating on surface of engineering plastics. In this paper, it compares tracking resistance, leakage current of the engineering plastic coated RTV with that of non-coated engineering plastic. And filled-composites performed much better than non-filled composites.

• 한국생산제조학회지
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• 제19권6호
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• pp.847-851
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• 2010

It was attempted to develop an auto part by over molding injection mold that produces precision products in high productivity with use of an eco-friendly TPE substitute material for NBR. NBR is currently used in motor gear cover, one of the key parts in motor module for auto doors. Gear cover is composed of plastics and rubber mostly today, which requires a two (2) step process for production using two presses of different types. A hot press is used at this time for forming the rubber, which has drawback of requiring a rather long forming time of 400 seconds for one forming process. Even though this difficulty is overcome by reducing production time through employment of multi-cavity molds, time for forming process must be shortened for improvement of the productivity eventually, and the existing method of insert injection for products that have been formed with plastic material must be outgrown. In this point of view, over molding injection using TPE has a big advantage. Forming time is shortened to 54 seconds, and working the two (2) processes in series by one (1) press could solve the durability problem caused by deflection of the plastics, not to mention shortening the process time. Enhancement of productivity by almost 80% and improvement in the accuracy of the product could thus be achieved.

• 대한기계학회논문집A
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• 제32권11호
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• pp.937-942
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• 2008

This research investigated to find out the possibilities of applying FRPs to the AUVs. In this study, two kinds of metal materials, which is one of the popularly used materials for manufacturing AUVs, and 6 kinds of FRP materials were considered. Material properties of FRPs were derived by tensile tests and chemical analysis. Moreover, various types of AUVs were designed by 8 kinds of materials. From structural analysis, we can find out that the weights of AUV by CFRP-Autoclave could be reduced by 60% in comparison with the weights of AUV by Al 7075-T6. Also, 40% weight reduction could be expected compared to the AUV by Ti-6Al-4V. In this result, we could conclude that the material of CFRP-Autoclave have various merits and potentialities as one of the AUV materials.

• 자원리싸이클링
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• 제14권3호
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• pp.55-62
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• 2005

굴 양식의 부산물인 패각과 혼합 폐플라스틱을 이용하여서 패각의 함유 및 패각 표면 재질에 따른 물성과의 상관관계에 관한 연구를 하였다. 먼저 패각과 순수 LDPE를 twin screw extruder를 시용하여 40 wt%의 마스터배치(masterbatch, M/B)를 제조한 후, 다시 이를 순수 LDPE와 섞어서 패각 함유 10 wt%에서 40 wt%까지의 사출용 시편을 제조하였다. 한편 순수 LDPE 대신에 혼합 폐플라스틱을 이용하여 상기와 동일한 방법으로 사출용 시편을 제조하였고, 패각과 혼합 폐플라스틱과의 상용성을 향상시키기 위해서 패각의 표면을 양이온과 양이온성 계면활성제로 치환하였다. 표면 개질 패각을 이용하여 혼합 폐플라스틱과의 혼입을 통해 상기와 동일 함량을 갖는 사출 시편을 제조한 후 기계적 물성을 측정하였다. 측정 결과 표면을 개질한 패각을 함유한 혼합 폐플라스틱은 미개질 패각 함유 시편에 비해 매트릭스와의 상용성 증가로 인해 굴곡강도, 압축강도, 열변형 온도 등의 물성 향상을 나타내었다. 따라서 패각을 함유시 혼합 폐플라스틱의 기계적 물성의 향상으로 인해 새로운 용도 개발이 가능한 것을 확인하였다.

• 한국정밀공학회지
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• 제17권3호
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• pp.108-113
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• 2000

An important process for making a new class of polymeric material is called microcellular plastics invented at the Massachusetts Institute of Technology. Many researches for microcellular plastics have been done in various ways and fields. But a research for the polymer which has previous history has not been tried yet. In this paper, weight gain of $CO_2$ was measured in a polymer matrix which had previous history and no history. In each case, experimental data for solubility and diffusivity was shown. A model for $CO_2$ solution process in molecular range was made. The conclusion of this paper is that the previous history has an effect on diffusivity but not solubility and the previous history made by $CO_2$ in supercritical state makes diffusivity of $CO_2$ larger.