Electrical conductivity of chemically modified multiwalled carbon nanotube/epoxy composites

摘要

The electrical conductivity of oxidized multiwalled carbon nanotubes (MWNT)/epoxy composites is investigated with respect to the chemical treatment of the MWNT.The oxidation is carried out by refluxing the as-received MWNT in concentrated HNO_3 and H_2O_2/NH_4OH solutions,respectively,under several different treatment conditions.The oxidized MWNT are negatively charged and functionalized with carboxylic groups by both solutions.The MWNT oxidized under severe conditions are well purified,but their crystalline structures are partially damaged.It is recognized that the damage to the MWNT has considerable influence on the electrical properties of the MWNT composites,causing the electrical conductivity to be lowered at a low content of MWNT and the percolation threshold to be raised.The MWNT oxidized by the mixture of H_2O_2 and NH_4OH solution provides epoxy composites with a higher conductivity than those produced with the MWNT oxidized by nitric acid over the whole range of MWNT,independently of the oxidation conditions.