Experimental Research on Electro-mechanical Coupling Effects of Carbon Nanotubes Fibers

CNT fibers are composed of millions of highly aligned CNTs. The mechanical properties of CNT fibers when passing through different intensities of currents were investigated experimentally. The experimental results show that the introduction of current can obviously reduce the modulus and breaking strength of the fibers. When the current passes through the fibers, an axial electro-contraction force is produced, the electro-contraction force is increased with the increase of current intensity, the electro-contraction force at 5mA is about 2.5mN. By stretching the fiber to the 2% strain axially, after 1000s of the stress relaxation, the load tends to be stable, then switch on current or increase the current intensity, it is found that the tension of the fiber is obviously decreased due to the decrease of the stress caused by the change of modulus is greater than the increase of electric-contraction force. Stretching the fiber axially to 2% strain when passing through a certain intensity of current, after the stress relaxation, the load tends to be stable, then the same intensity of AC current is passed through, the response of the electro-contraction force is very quick.When the AC current changes experience 400 cycles, electro-contraction force exhibits good change, which makes the CNT-fibers as a new type of electro-actuation material.