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Carbon Nano Tube (CNT) ¸¦ È¿°úÀûÀ¸·Î »ç¿ëÇϱâ À§Çؼ´Â CNT ¸¦ distribution ÇÏ°í dispersion ÇÏ´Â °ÍÀÌ ¸Å¿ì Áß¿äÇÑ ÀÛ¾÷ÀÌ´Ù.
CNT ÀÇ tube ´Â ÇÕ¼º°úÁ¤ µîÀÇ °úÁ¤¿¡¼ °·ÂÇÑ van der waals force ¿¡ ÀÇÇØ agglomerate ¶Ç´Â bundle ÇÏ°Ô µÇ¾î entangled structure ¸¦ ¶ç°Ô µÇ´Âµ¥
ÀÌ ±¸Á¶¿¡ ÀÇÇØ CNT ´Â aqueous ¿¡¼ stability °¡ ¸Å¿ì ¶³¾îÁö°Ô µÈ´Ù. ¶ÇÇÑ CNT Ç¥¸éÀÇ functional group ¿¡ ÀÇÇؼµµ CNT ÀÇ dispersability (ºÐ»ê´É or ºÐ»êÁ¤µµ) °¡
Å©°Ô ¿µÇâÀ» ¹Þ°Ô µÈ´Ù. ±×·¯¹Ç·Î CNT ÀÇ dispersability ¸¦ °£ÆíÇÏ°í Á¤È®ÇÏ°Ô ºÐ¼®ÇÒ ¼ö ÀÖ´Â ±â¹ýÀÌ ¸Å¿ì ÇÊ¿äÇÏ´Ù. º» ¿¬±¸¿¡¼´Â ¸î°¡Áö ÇüÅÂÀÇ CNT ¸¦
dispersion ½ÃŲ ´ÙÀ½ °¢ sample ÀÇ dispersion Á¤µµ¸¦ analytical centrifuge ÀÎ LUMiFuge (LUM) ¸¦ ÀÌ¿ëÇÏ¿© ºÐ¼®ÇÏ¿© analytical centrifuge ÀÎ LUMiFuge (LUM) ÀÌ
CNT ÀÇ dispersability ¸¦ ¾î´À Á¤µµ Á¤È®È÷ ºÐ¼®ÇÏ´ÂÁö¸¦ »ìÆ캸¾Ò´Ù.
Å×½ºÆ®¿¡ »ç¿ëµÉ CNT ´Â NC7000, TsNa1, TsNa2, CNT1, CNT2, CNT3, CNT4 ÃÑ 7°¡Áö sample À» ÁغñÇÏ¿´´Ù.
NC7000 Àº Nanocyl S.A.,( Sambreville, Belgium) ¿¡¼ ±¸ÀÔÇÏ¿´°í TsNa1, TsNa2 Àº TsinghuaNafine Nano-Powder Commercialization Engineering
Center (Beijing, China) ¿¡¼ ±¸ÀÔÇÏ¿´´Ù.
Fixed-bed technology ¿¡ ÀÇÇØ Á÷Á¢ ÇÕ¼ºÇÑ CNT1 Àº single/double-walled CNT ¿Í multi-walled CNT °¡ µ¿ÀϺñÀ²·Î ¼¯¿©ÀÖ´Â mixture À̸ç CNT2,3,4 ´Â
aerosol technology ¿¡ ÀÇÇØ ÇÕ¼ºµÈ °ÍÀÌ´Ù. CNT2, 3 Àº cyclohexane À» ÀÌ¿ëÇØ ÇÕ¼ºµÇ¾úÀ¸¸ç CNT4 ´Â acetonitrile À» ÀÌ¿ëÇØ ÇÕ¼ºÇÑ °ÍÀÌ´Ù.
ÀÌ ¸ðµç CNT ´Â functional group À» °¡ÁöÁö ¾Ê´Â °ÍÀ̸ç CNT ÀÚü¿¡ defects °¡ ¾ø´Â °ÍÀ» RAMAN spectroscopy µîÀÇ ¹æ¹ýÀ¸·Î È®ÀÎÇÏ¿´´Ù
ÀÌ·¸°Ô ÁغñÇÑ aqueous CNT ¿¡ surfactant ¸¦ ³Ö°í ultrasonication À» ÇÏ¿© CNT ¸¦ ºÐ»êÇÏ¿´´Ù. ¿©±â¿¡ »ç¿ëµÈ surfactant ´Â anioinc surfactant ÀÎ
SDDBS (sodium dodecylbenzene sulfonate) ·Î¼ sodium dodecyl sulphate (SDS) ¿Í °°Àº surfactant ¿¡ ºñÇØ È¿°ú°¡ °¡Àå ¶Ù¾î³ª´Ù.
Ultrasonication Àº 20kHz, 40 Watt ¿¡¼ 2½Ã°£ ó¸®ÇÏ¿´´Ù.
SDDBS ¸¦ ÷°¡ÇÑ CNT sample À» ultrasonication (ÃÊÀ½ÆÄó¸®) ÇÑ ´ÙÀ½ LUMiFuge 114 Stability Analyzer (L.U.M. Gmbh, Berlin, Germany) ¸¦ ÀÌ¿ëÇÏ¿©
CNT sample ÀÇ sedimentation behaviour ¸¦ ºÐ¼®ÇÏ¿´´Ù. LUMiFuge ´Â sample À» ¿ø½ÉºÐ¸®ÇÏ¸é¼ space and time resolved extinction profiles ¸¦ ³ªÅ¸³» ÁÖ´Â
microprocessor controlled analytical centrifuge ·Î¼ sample À» °í¼ÓÀ¸·Î ȸÀü½ÃÅ°¸é tube ³»¿¡¼ dispersed particle ÀÌ tube ÀÇ bottom ¹æÇâÀ¸·Î À̵¿ÇÏ°Ô µÇ´Âµ¥
dispersion ÀÌ ÀßµÈ °æ¿ì À̵¿Á¤µµ°¡ ¸Å¿ì ³·°í ¹Ý´ëÀÇ °æ¿ì À̵¿Á¤µµ°¡ »ó´ëÀûÀ¸·Î ºü¸£°Ô µÈ´Ù. NIR (Near Infrared) light ¸¦ tube ¸¦ Åë°ú½ÃÄÑ tube °¢ ÁöÁ¡¿¡¼ÀÇ
transmission Á¤µµ¸¦ Curve ·Î ³ªÅ¸³»°Ô µÈ´Ù. ½Ã°£¿¡ µû¸¥ Àüü transmission curve ÀÇ º¯È¸¦ ÇϳªÀÇ ±×·¡ÇÁ¿¡ Ç¥½ÃÇÑ °ÍÀÌ Transmission Profile ÀÌ µÈ´Ù.
ÀÌ transmission profile À» ºÐ¼®Çϸé sample ÀÇ dispersion stability ¸¦ Á¤È®ÇÏ°Ô ºÐ¼®ÇÒ ¼ö ÀÖ´Ù. Good nanoparticle dispersion ÀÎ °æ¿ì
¸ðµç nanoparticle ÀÌ surfactant ¿Í wetting ÀÌ µÇ¾î stability °¡ ÁÁ°í sedimentation rate °¡ ¸Å¿ì ³·°Ô µÇ´Â°ÍÀÌ´Ù.
¶ÇÇÑ transmission profile ¿¡¼ 100 ? 110mm »çÀÌÀÇ profile ÀÇ º¯È¸¦ ÇϳªÀÇ ±×·¡ÇÁ·Î Ç¥½ÃÇÏ´Â integral transmission ¸¦ ÀÌ¿ëÇϸé sedimentation velocity ¸¦
ºÐ¼®ÇÒ ¼ö ÀÖ¾î ´Ù¾çÇÑ dispersion stability °ü·Ã data ¸¦ ±¸ÇÒ ¼ö ÀÖ´Ù.
´ÙÀ½ µµÇ¥´Â °¢ CNT sample ÀÇ transmission profile µéÀÌ´Ù.
¸ðµç CNT sample ÀÇ transmission profile ¿¡¼ ¼öÆòÀ¸·Î ³ªÅ¸³ª´Â ºÎºÐÀÌ Àִµ¥ ÀÌ´Â sample ³» ÀÔÀÚ Å©±â ºÐÆ÷°¡ ³Ð°í °¢ ÀÔÀÚµéÀº °¢°¢ÀÇ
sedimentation velocity ¿¡ ÀÇÇØ Ä§°ÇÏ°í ÀÖ´Ù´Â °ÍÀ» ÀǹÌÇÑ´Ù. ¸ðµç sample ÀÌ transmission value °¡ Áõ°¡ÇÏ´Â °ÍÀ» º¼ ¼ö ÀÖÀ¸³ª NC7000, TsNa1, CNT3, CNT4 ÀÇ
°æ¿ì 9-10 transmission % ±îÁöÀÇ transmission value °¡ ¸Å¿ì ³·°Ô ÀÌ·ç¾îÁö°í ÀÖ´Ù.
¾Æ·¡ µµÇ¥´Â °¢ transmission profile ¿¡¼ 100-110mm tube À§Ä¡¿¡¼ °¢ profile À» integration ÇÑ integral transmission À» Ç¥½ÃÇÑ °ÍÀ¸·Î ÇØ´çÀ§Ä¡¿¡¼
transmission profile ÀÇ º¯È¸¦ ÅëÇØ ½Ã°£¿¡ µû¸¥ dispersion stability ¿Í sedimentation rate ¸¦ ÇÑ´«¿¡ ¾Ë ¼ö ÀÖ´Ù.
À§ µµÇ¥¿¡¼ ±×·¡ÇÁÀÇ ±â¿ï±â°¡ ¿Ï¸¸ÇÑ NC7000, TsNa1, CNT3, CNT4 ´Â dispersion stability °¡ ¸Å¿ì ¶Ù¾î³ª°í CNT1 °ú TsNa2 ´Â stability °¡ Çö°ÝÈ÷ ¶³¾îÁø´Ù´Â °ÍÀ» ¾Ë ¼ö ÀÖ´Ù.
CNT2 °æ¿ì Ãʱ⿡´Â ¿Ï¸¸Çϳª Áß¹Ý ÀÌÈÄ¿¡ ±â¿ï±â°¡ Áõ°¡Çϴµ¥ ÀÌ´Â two-step sedimentation ÀÌ ÀϾٴ °ÍÀ» ÀǹÌÇÑ´Ù.
LUMiFuge Stability Analyzer ¸¦ ÀÌ¿ëÇÑ CNT material ÀÇ dispersion stability ºÐ¼® °á°ú´Â electron percolation threshold ºÐ¼®, Particle Image Analyzer ¸¦ ÀÌ¿ëÇÑ
À̹ÌÁö ºÐ¼®, SEM ºÐ¼°ú °°Àº ´Ù¸¥ ºÐ¼® ±â¹ýÀ» ÀÌ¿ëÇÏ¿© ±¸ÇÑ °á°ú¿Í µ¿ÀÏÇÏ¿´´Ù.
LUMiFuge Stability Analyzer ¸¦ ÀÌ¿ëÇÑ dispersion stability ºÐ¼®±â¹ýÀº STEP Space & Time Resolved Extinction Profile) Technology ¶ó ºÎ¸£¸ç
ºÐ»ê ¾ÈÁ¤¼º ºÐ¼®¿¡ Ź¿ùÇÏ´Ù°í ÇÒ ¼ö ÀÖ´Ù,.
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