Effect of masterbatch (MB) on the properties of polypropylene/multi-walled carbon nanotube (PP/MWCNT) nanocomposites was studied. Nanocomposites with same compositions but different fabrication protocols were compared. In one-step mixing protocol, PP and MWCNT were compounded at once. In two-step mixing protocol, MB was first prepared from PP and high concentration of MWCNT and followed by subsequent dilution process with additional PP and MB. It was found that two-step protocol using MB enhanced the dispersion of MWCNTs and consequently mechanical and electrical properties were improved. When the MB was fabricated by PP, MWCNT and polypropylene-g-maleic anhydride (PP-g-MA), the properties of resulting nanocomposites were higher than those without PP-g-MA. This is attributed to increased affinity between matrix polymer and MWCNT due to the increased polarity of matrix polymer by incorporation of PP-g-MA. When PP of lower viscosity was used for the MB, the dispersion of MWCNT was much enhanced and the mechanical and electrical properties were also increased.

Polypropylene/multi-walled carbon nanotube(PP/MWCNT) 나노복합재료를 제조할 때 마스터 배치(MB)의 사용 효과에 대하여 고찰하였다. PP와 MWCNT를 한 번에 압출하여 제조한 나노복합재료와 PP에 고농도의 MWCNT를 혼합하여 MB를 제조한 후 여기에 PP를 혼합하는 두 단계의 압출을 통하여 제조한 나노복합재료를 비교하였다. 두 단계로 압출하는 것이 한 단계의 압출보다 MWCNT의 분산이 우수하고 높은 기계적 강도 및 전기적 특성을 보임을 알 수 있었다. 또한 MB 제조 시 MWCNT와 동일한 양의 PP-g-MA(maleic anhydride grafted PP)를 첨가하여 만든 MB를 사용하면 더욱 우수한 물성을 가진 나노복합재료를 얻을 수 있었다. 이는 극성이 낮은 PP에 극성이 높은 PP-g-MA를 혼합함으로써 MWCNT와의 친화성을 높이기 때문인 것으로 분석되었다. MB 제조 시 사용되는 PP의 점도가 낮을수록 균일한 MWCNT의 분산을 얻을 수 있었고 기계적 물성 및 전기 전도도가 증가하였다.

Keywords: polypropylene, carbon nanotube, master batch, viscosity effect, polypropylene-g-maleic anhydride