• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.288-291
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• 2002

The carbon fiber or glass fiber reinforced prepregs were manufactured using electrostatic flocking technology. The powder of high density polyethylene was used as a matrix. The base film of polyethylene was prepared using a fluidized bed of polyethylene powder under the high electric field. We obtained HDPE film with uniform thickness of minimum $80\mu\textrm{m}$. And the fibers were aligned on the molten HDPE film by the electroflocking process. The short fibers with 1mm were easily electrically charged and aligned under the high electric field. The carbon fibers with high conductivity were elasily electrically charged than the glass fibers with low conductivity. So lower electric field was needed for the carbon fibers.

• Elastomers and Composites
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• 제26권1호
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• pp.15-22
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• 1991

Blends of ethylene-propylene-diene terpolymer(EPDM) and high density polyethylene(HDPE) have been prepared in a roll mill by the process "dynamic curing" where both blending and a crosslinking reaction was carried out simultaneously. As a crosslinking agent, dicumyl peroxide(DCP) was used. Throughout the experimental ranges, the dynamically cured polyblends were shown to be thermoplastic elastomers except highly crosslinked blends of high compositions of EPDM. The increase of melt viscosity was observed as EPDM composition and DCP contents increased. From DSC determinations, the crystallinity decreased with increasing contents of DCP. The tensile strength and elongation at break generally increased with increasing DCP content and increasing HDPE compositions, but highly depended on the combined effects of decreasing crystallinity and increasing crosslinking density.

• 대한기계학회논문집A
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• 제39권4호
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• pp.405-413
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• 2015

최근 미국에서는 가동기간이 오래된 원전 매설배관에서 부식 및 침식에 의해 삼중수소 누설로 지하수가 오염되는 사례가 급증하고 있다. 따라서, 현재 원전 안전등급 매설배관으로 사용되고 있는 금속재료의 배관을 대신해서 부식 및 침식 등의 열화 손상에 대한 저항성이 우수한 고밀도 폴리에틸렌(HDPE) 배관을 ASME Code Class 3 안전계통 배관으로 사용하기 위한 연구가 수행되고 있다. 본 연구에서는 발전소 가동 중 매설배관에 가해질 수 있는 하중과 온도 범위를 바탕으로 HDPE 배관 융착부에 대한 인장 시험과 저속균열성장 (SCG) 시험을 수행하였다. 시험 결과로 얻은 SCG 시험편의 파단면을 분석하여 HDPE 재료의 파손 기구를 파악하였다. 이를 바탕으로 3D 유한요소 해석을 이용하여 균열이 있는 HDPE 재료가 버틸 수 있는 한계하중에 대한 검증을 수행하였다.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.255-261
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• 2022

A reliable and well-characterized dosimetry system which is traceable to the international measurement system, is the key element to quality assurance in radiation processing with cobalt-60 gamma rays, X-rays, and electron beam. This is specifically the case for health-regulated processes, such as the radiation sterilization of single use medical devices and food irradiation for preservation and disinfestation. Polyethylene is considered to possess a lot of interesting dosimetric characteristics. In this work, a detailed study has been performed to determine the dosimetric characteristics of a commercialized high-density polyethylene (HDPE) film using Fourier transformed infrared spectrometry (FTIR). Correlations have been established between the absorbed dose and radiation induced infrared absorption in polyethylene having a maximum at 965 cm^-1 (transvinylene band) and 1716 cm^-1 (ketone-carbonyl band). We have found that polyethylene dose-response is linear with dose for both bands up to1000 kGy. For transvinylene band, the dose-response is more sensitive if irradiations are made in helium. While, for ketone-carbonyl band, the dose-response is more sensitive when irradiations are carried out in air. The dose-rate effect has been found to be negligible when polyethylene samples are irradiated with electron beam high dose rates. The irradiated polyethylene is relatively stable for several weeks after irradiation.

• Korean Chemical Engineering Research
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• 제61권1호
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• pp.80-88
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• 2023

저밀도 폴리에틸렌(Low-density polyethylene, LDPE)은 분진폭발 관련 특성치에 대한 기준이 제시되고 있지 않아 제조 및 취급설비의 안전한 설계가 어렵다. 이 연구에서는 LDPE 제조공정 중 Bag Filter에서 채취한 분진(LDPE 1)과 Silo 등의 설비 외부에 누설된 퇴적 분진(LDPE 2)에서 채취한 2개 시료에 대하여 분진폭발 시험을 수행하였고 그 중 LDPE 2 분진에 대하여 요약하였다. 입도분석 결과, 체적기준 평균입경은 95.04 ㎛, 수밀도는 0~1 ㎛로 나타났다. 최대폭발압력(P_max)은 6.6 bar, 최대폭발압력상승속도는 1500 g/m³에서 366 [bar/s]로 분진폭발지수(K_st)는 99.4 bar·m/s로 ST-1 등급임을 확인하였다. 또한, 최소점화에너지는 10 mJ이며 최소점화온도는 450 ℃로 나타났다. 현재, 제조 및 취급 설계는 고밀도 폴리에틸렌(HDPE)의 특성값을 기초로 한다. 그러나, 시험 결과 LDPE 2 분진이 HDPE(입자지름 61.6 ㎛)보다 위험성이 높은 것으로 나타나 LDPE 제조공정에서 HDPE 설계기준을 적용할 때는 주의가 필요하다.

• Macromolecular Research
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• 제17권8호
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• pp.580-584
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• 2009

The effects of crystallinity and radiation crosslinking on the physical properties of a microporous high density polyethylene (HDPE) film with Millad3988 as a nucleating agent were investigated. The pores of the HDPE film were affected by the crystallinity. The crystallinity of the HDPE films increased with increasing Millad3988 amount up to 0.1 wt% but decreased with further addition. The mechanical characteristics of the HDPE containing Millad3988 films improved with increasing irradiation dose up to 50 kGy, but decreased at 75 kGy due to severe degradation. The thermal shrinkage behavior of the HDPE films decreased with increasing radiation dose up to 50 kGy. The porosity of the stretched HDPEIMillad3988 films after ${\gamma}$-ray radiation increased with increasing y-ray radiation dose up to 50 kGy. The pores of the irradiated films were formed more easily by a stretching due to the formation of a crosslinked structure.

• 한국인터넷방송통신학회논문지
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• 제16권6호
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• pp.239-242
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• 2016

본 논문에서는 이중 곡률을 갖는 오목 렌즈를 제안하였다. 이중 곡률 렌즈는 HDPE (High Density Polyethylene)를 이용하여 제작하였다. 이중 곡률 렌즈는 두 개의 오목 구조로 구성되었다. 두 개의 오목 구조의 역할은 빔을 균일하게 넓게 보내기 위함이다. 작은 오목 구조는 큰 오목 구조 보다 더 큰 곡률 반경을 갖는다. 이러한 이중 곡률 렌즈는 밀리미터파 이미징 시스템에 적용 가능하다. 제작된 이중 곡률 렌즈를 250 GHz VDI 소스를 이용하여 검증하였다. 광학 시뮬레이션 툴인 ZEMAX를 이용하여 설계하고 제작된 렌즈는 균일한 빔과 확장 성능을 충분히 수행함을 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제32권6호
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• pp.67-73
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• 2004

The influence of liquefied wood (LW) on the mechanical and thermal properties of liquefied wood-polymer composites (LWPC) was investigated in this study. The thermal behaviors of LWPC were characterized by means of thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. LW showed significant effects on the mechanical strength properties. The increase of flexural MOE and Young's modulus was related to the increase of stiffness of LWPC. The effect of LW was also significant on the flexural and tensile MOR. The impact strength decreased with the increase of LW application level. With the increased stress concentration by the poor bonding between LW and polymer, the impact strength of LWPC decreased, compared with that of high-density polyethylene (HDPE). The thermal stability of LWPC decreased with the increase of LW content up to 40%. The melting temperature of HDPE decreased with the increase of LW loading level. Enthalpy of HDPE also decreased with the addition of LW. This study proves the thermal stability necessary for the consolidation of composition materials.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1754-1761
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• 2024

In hadrontherapy, secondary fragments are generated by nuclear interactions of the incident heavy ion beam with the atomic nuclei of the target. It is important to determine the yield of production and the dose contribution of these secondary fragments in order to determine the radiobiological effectiveness more accurately. This work aims to fully identify the secondary fragments generated by nuclear interactions of proton and helium (⁴He) ion beams in a High-Density Polyethylene (HDPE) target and to investigate the dose contributions by secondary fragments. Incident protons with energies of 55.90 MeV and 105.20 MeV and helium ions with energies of 52.55 MeV/u and 103.50 MeV/u in the HDPE phantom have been investigated by the means of Geant4 Monte Carlo (MC) simulations. Simulated results were validated using NASA Space Radiation Laboratory (NSRL) Bragg curves experimental data. The results showed that the dose contribution of secondary fragments deriving from helium ion beams is three times higher than in the case of proton beams. This is due to a higher production of nuclear fragments in the case of helium ion beams. This work contributes to a better understanding of secondary fragments generated by protons and helium ions in the HDPE target.

• 폴리머
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• 제29권1호
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• pp.32-35
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• 2005

탄소나노튜브를 오존처리한 후 이를 사용하여 탄소나노튜브/고밀도 폴리에틸렌 전도성 복합재료를 제조하였고, 오존처리된 탄산나노튜브가 positive temperature coefficient(PTC) 세기에 미치는 영향을 조사하였다. 원소분석(EA)과 FT-IR 분석 결과, 오존처리된 탄소나노튜브의 표면에는 O-H, C=O 그리고 C-O와 같은 산소함유 관능기가 증가하는 것을 확인할 수 있었다. 또한, 전도성 복합재료의 온도에 따른 저항성은 디지털 멀티메타를 이용하여 측정하였다. 복합재료의 저항성은 고밀도 폴리에틸렌의 결정 용융 온도에서 증가하였으며, 이는 복합재료의 매트릭스로 사용된 고밀도 폴리에틸렌의 열팽창성에 의한 전도성 네트워크의 파괴때문인 것으로 판단된다. 그리고 탄소나노튜브에 오존처리 시간이 증가할수록 탄소나노튜브/고밀도 폴리에틸렌 복합재료의 PTC 세기는 증가했고, 이는 오존처리에 의한 탄소나노튜브 표면에 산소함유 관능기는 PTC 소자의 최대 비저항 값을 증가시키기 때문인 것으로 판단된다.