The electrical behaviour of laminated conductive polymer composite at low temperatures

The study deals with the electrical characteristics of laminated conductive polymer composites consisting of epoxy and carbon fibers with different concentration. The composites contain 7, 17.5, and 25.2 wt% carbon fibers (10, 25, and 36 layers of carbon fibers), respectively. The DC electrical conductivity was studied as a function of filler concentration in low temperature range 25–275 K. It was found that the composites exhibit negative temperature coefficient of resistivity (TCR) and electrical conductivity enhancement with temperature and carbon fibers concentration. The semiconducting behavior of the observed electrical conductivity is characterized by two different regions: high temperature range where the conductivity increases gradually (thermal process) and low temperature range where the conductivity increases with a less rate (Motts hopping process) with increasing of temperature.