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고선택성 폴리이미드 소재의 합성 및 분자동력학 연구를 통한 기체투과도의 비교
이정무,김득주,정문기,이명건,박치훈,남상용,Lee, Jung Moo,Kim, Deuk Ju,Jeong, Moon Ki,Lee, Myung Gun,Park, Chi Hoon,Nam, Sang Yong 한국막학회 2015 멤브레인 Vol.25 No.2
In this study, gas permeability of polyimide materials having a various amine group was measured and molecular dynamics was used to analyze the dynamic characteristics of the gas molecules in the polyimide by calculating the position and velocity of the gas molecules with change of the time. The gas permeability of polyimide membrane having substitution site which increase free volume in the polymer was increased. However, polyimide with rigid structure showed decreased gas permeability. As a result of analyzing the change in the gas permeation behavior using molecular dynamics simulations, we confirmed that the results show the same tendency with actual measurements of the gas permeability. 본 연구에서는 다양한 아민기를 가지는 폴리이미드 소재 및 분리막을 제조하여 그들의 구조의 변화에 따른 기체 투과도를 측정하였으며 동력학(Molecular dynamics; MD) 기술을 이용하여 해당 기체의 시간의 변화에 따른 위치와 속도를 계산하여, 기체분자의 동적 특성을 분석하는데 활용하였다. 투과도 측정결과 합성된 고분자 소재의 경우 고분자 내의 free volume을 증가시키는 치환기를 도입시켰을 경우 기체투과도가 증가되었으나 rigid한 구조가 도입된 폴리이미드는 투과도가 감소되는 경향을 확인하였다. 또한 분자동력학 시뮬레이션을 이용하여 기체투과거동 변화를 분석한 결과 실제 기체투과도 측정결과와 유사한 결과를 나타냄을 확인할 수 있었다.
이정무,이명건,김세종,고형철,남상용,Lee, Jung Moo,Lee, Myeong Geon,Kim, Se Jong,Koh, Hyung Chul,Nam, Sang Yong 한국막학회 2015 멤브레인 Vol.25 No.3
새로운 구조를 가진 공중합체 폴리이미드를 이용하여 고투과, 고선택성 기체 분리막을 제조하였다. 기체투과도와 용해도를 높이기 위해 무수물인 2,2-bis(3,4-carboxylphenyl) hexafluoropropane과 두 종류의 아민인 2,4,6-Trimethyl-1,3-phenylenediamine과 4,4-Methylenedianiline을 사용하여 신규 폴리이미드를 합성하였다. Triethylamine과 Acetic anhydride를 사용하여 화학적 이미드화 방법으로 공중합체를 합성하였으며, 평균분자량은 100,000 g/mol 이상을 나타내었다. 합성된 고분자의 열적 특성을 분석을 하기 위해 시차주사열량계(DSC)와 열중량분석기(TGA)로 측정을 하였으며, 유리전이온도(Tg)는 $300^{\circ}C$, 열분해 온도는 $500^{\circ}C$가 넘는 뛰어난 내열성을 나타내었다. 기체투과도 특성은 time-lag 장비를 사용하였으며 그 결과, 일반적인 폴리이미드의 경우 대부분 기체투과도가 1 barrer 이하의 수치를 보이지만, 합성된 고분자의 경우 산소투과도 10.10 barrer과 산소/질소 선택도의 경우 5.3으로 고투과, 고선택도를 나타내어 기체 분리막 분야에 적용 가능성을 확인할 수 있었다. 합성된 고분자 중 기체투과특성이 더 우수한 공중합 폴리이미드를 사용하여 중공사를 제조하였고, 이를 이용하여 기체투과특성을 측정하였다. We synthesized novel polyimides with high gas permeability and selectivity for application of gas separation membrane. 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) and two kinds of amines with high permeability and solubility were used to prepare the novel polymide. 2,4,6-Trimethyl-1,3-phenylenediamine (DAM) was used to improve gas permeability and 4,4-Methylenedianiline was used to improve the gas selectivity respectively. The polyimide copolymers were synthesized by commercial chemical imidization method using Triethylamine and Acetic anhydride and their average molecular weights were over 100,000 g/mol. The glass temperature (Tg) and the thermal degradation temperature were characterized using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The synthesized copolymers showed high Tg over $300^{\circ}C$ and high thermal degradation temperature over $500^{\circ}C$. The gas permeation properties were measured by time-lag equipment. Although general polyimides showed very low gas permeability, synthesized polyimide copolymer showed high $O_2$ permeability of 10.1 barrer with high $O_2/N_2$ selectivity around 5.3. From this result, we confirm that these membranes have possibility to apply to gas separation membrane.
논문 : 복합 재료 ; A356/SiCp 복합재료와 semi-metallic pad재의 건식 미끄럼 마멸 특성
이정무 ( Jung Moo Lee ),강석봉 ( Suk Bong Kang ),( Yun Xue Jin ) 대한금속재료학회 ( 구 대한금속학회 ) 2007 대한금속·재료학회지 Vol.45 No.9
The dry sliding wear tests were performed on A356/20vol.% SiCp composites against semi-metallic pad materials. The samples were tested by pin-on-disc wear test equipment with different applied load and sliding velocity. The wear properties of A356/20vol.% SiCp against semi-metallic pad have exhibited good results with low wear rate even at the 700N applied load and 4.0 m/s sliding velocity and low friction coefficient in the range of 0.2-0.3. Wear behavior was examined through the observations and analysis of the worn surface, worn subsurface and wear debris. It is revealed that the oxide powders and carbon transferred from the counterpart formed on the worn surface and acted as lubricant to reduce the wear rate. In addition, platelike wear debris has been formed on the worn surface. The platelike wear debris is formed due to the plastic flow and increase of temperature on top of the worn surface.
가스 - 입자 동시주입법에 의한 A356 / SiCp 복합재료의 제조 및 기계적 특성
이정무(Jung Moo Lee),강석봉(Suk Bong Kang),엄철용(Chil Yong Eum),임차용(Cha Yong Lim) 한국주조공학회 2001 한국주조공학회지 Vol.21 No.1
Among the many techniques available to synthesis metal matrix composites, liquid phase processing, especially, conventional casting process such as stir-casting process is particularly attractive for their simplicity, economy and flexibility. In the present study, A356/20%SiCp composites were fabricated by gas-particle co-injection method. The gas-particle co-injection method is a modified stir-casting method and the corporation of particle could be improved by acceleration of particles due to rotation of impeller and gas purging. The microstructures and mechanical properties such as tensile properties and resistance to wear of fabricated materials were examined. Further, the particle injection mechanism in gas-particle co-injection method was discussed.
A357합금에서 용탕처리가 미세조직 및 기계적 특성에 미치는 영향
이정무 ( Jung Moo Lee ),이성학 ( Sung Hak Lee ),윤지현 ( Ji Hyun Yoon ),김경현 ( Kyung Hyun Kim ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.2
N/A The present work was undertaken to investigate the mutual effect of the individual melt treatment commonly applied in aluminum foundries such as grain refining, modification, degassing and filtration on the microstructures and the mechanical properties. A357 alloys were fabricated through various melt treatments such as degassing by gas bubbling filtration, modification via the addition of Al-Sr master alloy, grain refining through the addition of Al-Ti-B master alloy and filtration before pouring of the melt. Each melt treatment was performed at its optimum condition reported in the literatures. The effects of each melt treatment and their interactions on the microstructures and mechanical properties of A357 alloy were examined.
자발연소반응을 이용한 (TiC+Al2O3)/Al 복합재료의 저온합성
이정무 ( Jung Moo Lee ),김수현 ( Su Hyeon Kim ),조영희 ( Young Hee Cho ),김제우 ( Je Woo Kim ),이재철 ( Jae Chul Lee ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.12
The formation of TiC and Al2O3 particles based on the self-combustion reaction of the Al-TiO2-CCuO system in an Al alloy melt was investigated. With an adequate amount of CuO in the system, a spontaneous reaction occurred within the Al alloy melt at 850℃ and thereafter was self-maintained, producing an Al matrix composite reinforced with thermodynamically stable TiC and Al2O3 particles. TiC and Al2O3 particles contributed to a considerable increase in the strength and stiffness, demonstrating the feasibility of this method as a practical application for structural parts.