• 제목/요약/키워드: polyacrylonitrile

검색결과 246건 처리시간 0.031초

A Study on Electrical Resistivity Behaviors of PAN-based Carbon Nanofiber Webs

  • Park, Soo-Jin;Im, Se-Hyuk;Rhee, John-M.;Lee, Young-Seak
    • Carbon letters
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    • 제8권1호
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    • pp.43-48
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    • 2007
  • The influences of various carbonization temperatures on electrical resistivity and morphologies of polyacrylonitrile (PAN)-based nanofiber webs were studied. The diameter size distribution and morphologies of the nanofiber webs were observed by a scanning electron microscope. The electrical resistivity behaviors of the webs were evaluated by a volume resistivity tester. From the results, the volume resistivity of the carbon webs was ranged from $5.1{\times}10^{-1}\;{\Omega}{\cdot}cm$ to $3.0{\times}10^{-2}\;{\Omega}{\cdot}cm$, and the average diameter of the fiber webs was varied in the range of 310 to 160 nm with increasing the carbonization temperature. These results could be explained that the graphitic region of carbon webs was formed after carbonization at high temperatures. And the amorphous structure of polymeric fiber webs was significantly changed to the graphitic crystalline, resulting in shrinking the size of fiber diameters.

관형 상용막에 의한 우유 농축 (Milk Concentration by Commerical Tubular Membranes)

  • 김인철;김정학;탁태문
    • 멤브레인
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    • 제9권1호
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    • pp.17-24
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    • 1999
  • 본 연구에서는 관형 상용막(ultrafiltration (UF), nanofiltration(NF)을 이용하여 우유를 농축하고 농축 성분의 변화를 알아보았다. 친수성막(sulfonated polysulfone (SPSf), polyacrylonitrile(PAN), cellulose acetate(CA)) 의 경우에는 투과유의 투과속도 감소가 완만하고 소수성막의 경우에는 투과속도 감소가 심하였다. UF 농축이 경우 전고형분, 단백질,지방 미네랄은 농축에 따라 증가하고 탄수화물은 감소하였다. NF 농축의 경우 UF와 같은 경향을 보였지만 탄수화물의 감소경향이 훨씬 적었다.

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Membrane Formation of Polyacrylonitrile and Its Copolymer

  • Ha, Seong-Yong;Park, Ho-Bum;Nam, Sang-Yong;Lee, Young-Moo
    • 한국막학회:학술대회논문집
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    • 한국막학회 1997년도 춘계 총회 및 학술발표회
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    • pp.34-35
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    • 1997
  • The phase inversion is a significant phenomena in the preparation of membranes and wet spinning. In both these processes, a viscous dope solution is precipitated in a nonsolvent bath and a porous structure is formed under certain conditions. Such structure could have been considered as a diffusion controlled process. The membrane formation of the polymer solution includes both phase separation and gelation. We have studied the influence of variables on the final structure and tried to control the porosity and ultrafiltration(UF) performance of the polyacrylonitrile(PAN) and its copolymer.

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