Impact and flexural properties of polypropylene composites reinforced with multi-walled carbon nanotubes

The effects of content and size of multi-walled carbon nanotubes (MWCNTs) on the impact and flexural properties of reinforced-polypropylene (PP) composites were investigated at room temperature. The results showed that the flexural modulus and maximum flexural stress increased with increase of the MWCNTs weight fraction, while effects of the diameter and average length-diameter ratio of the fillers on the flexural strength were insignificant. The effects of the size and content of the MWCNTs on the impact fracture toughness were significant, the Izod V-notched impact fracture strength increased roughly with increasing weight fraction and the average diameter of the MWCNTs, while it decreased with increasing length-diameter ratio of the MWCNTs. Finally, the reinforcing and toughening mechanisms of the PP/MWCNTs composites are discussed.