| 초록 |
Electrical conductivities of the oxidized multiwalled carbon nanotubes (MWNT) /epoxy composites are investigated with respect to the chemical treatment of MWNT. The Oxidation is carried out by refluxing the as-received MWNT in concentrated HNO3 at the various conditions. The surface states of the oxidized MWNTs are analyzed through FTIR, TEM, and zeta potential measurement. The oxidized MWNTs are negatively charged and functionalized with carboxylic group. It was found that the degree of functionalization is varied depending on treatment time, treatment temperature and acid concentration. As the condition of oxidation get rigorous, the impurities in as-received MWNTs are removed well while crystalline structures of the MWNT are severly damaged. In order to estimate the damage effect of MWNTs on electrical property, the behavior of DC and AC conductivity in the different composite systems are evaluated by using percolation theory with the volume percent of MWNT. The percolation transition occurs at relatively low MWNT content with decrease in damage of MWNT. Not only less damaged-MWNT/epoxy composite showed much higher values in electrical conductivity than much damaged-MWNT/epoxy composite at the same content of MWNT but also the percolation transition occurs at lower content of MWNT compared to much damaged-MWNT composite. |
