Strength and actuation of carbon nanofiber/polypyrrole conducting composite films

Several kinds of conducting polymers have been used for small actuators and sensors. They, however, usually produce slow response and small actuating force. Such disadvantages have been improved in this study by means of using the composite material of conducting polymer and carbon nanofiber. Single layer thin films of PPy (polypyrrole) and composite material consisting of CNF (carbon nanofiber) and PPy were successfully fabricated by the electrophoretic and polymerization method newly developed for this research. The strain of pure PPy films was 12.6% and for a 10 wt% CNF/PPy composite film, the strain was 8.6%. It was noticed from the experiments that the strain of CNF/PPy was reduced as CNF weight ratio increased. Bending occurred for both pure PPy and CNF/PPy films when subjected to electric current. The tip deflections of the films varied from 0.5mm to 2mm. Tension tests were performed with 0%, 3%, 5%, and 7% weight ratio of CNF's. A single layer of pure PPy film showed Young's modulus of 20.05MPa. Specimens with a higher CNF ratio show larger moduli. The tests showed that CNF/PPy composite films may generate large forces and sensing sensitivity.