Mechanical and interfacial evaluation of CNT/polypropylene composites and monitoring of damage using electrical resistance measurements

Carbon nanotube (CNT)/polypropylene (PP) composites were compounded using a solvent dispersion method to more uniformly disperse the filler. A twin screw extruder was then used to manufacture specimens. The effect of low CNT concentrations on the mechanical and interfacial properties of PP were investigated using tensile and impact tests as well as a pull-out test of a microdroplet of the composite, on a single fiber. Low concentrations of CNT resulted in small, but significant increases, in Young's modulus, impact strength and interfacial adhesion. The increase in these mechanical properties is attributed to good reinforcing effects of the CNT filler. Measurement of the change in electrical resistance during bending and fatigue loading was used to monitor internal damage in the CNT/PP composite specimens. For CNT/PP composites with low CNT concentrations, these resistance measurements provide useful insight into internal failure, during cyclic loading.