Reinforcing carbon fibers as sensors: The effect of temperature and humidity

We investigated how temperature and relative humidity affects the electrical resistance of reinforcing carbon fibers in polymer composites. We used hybrid composites in which a tight, carbon fiber roving was laminated inside glass fiber-reinforced epoxy specimens. The electrical resistance of the carbon fibers was monitored continuously while the temperature or relative humidity was varied. The specific resistance was calculated in order to compare the different effects acting on the resistance of the carbon fiber. We found a relationship between temperature or relative humidity and specific resistance. As a result, carbon fibers can be used in different applications (for example in cure process monitoring). On the other hand, the effects should be compensated for when the resistance of the carbon fiber is measured in a health monitoring application (e.g. as an elongation sensor).