2006 Volume 55 Issue 8 Pages 766-771
In this work, the three-phase composites of CNF/NiTi/UPR, carbon nanofiber (CNF), shape memory alloy particles (NiTi) and unsaturated polyester resin (UPR), are innovated, and their electrical properties are investigated. It is found that the CNF/NiTi/UPR composite materials are of very low electrical percolation threshold due to CNF. Their electrical resistance increases with increasing NiTi particles in spite of being significant percolation threshold. The effect of the filler content on the electrical conductivity is discussed as a function of temperature. Moreover, the three-phase composites express a positive temperature coefficient (PTC), and its intensity increases around the percolation threshold because of the contribution of NiTi particles of 5wt% and 10wt%. The electrical resistance reduces with the increment of thermal cycle number. For the time dependence of electrical property, there exist the characteristics of a dynamic percolation and overcurrent protective effect with current attenuation. It is shown that the relation between current and voltage is linear and the electrical conductivity obeys an Ohmic law for these three-phase composites.
