Electrical, thermal, and mechanical properties of polypropylene/multiwalled carbon nanotube micromoldings

Abstract In this paper, properties of microparts molded from polypropylene/multiwalled carbon nanotubes (PP/CNT) composites were studied in detail. Results indicated that the percolation threshold of PP/CNT microparts shifted to higher filler concentrations when compared with their compression molded counterparts. Morphology observations revealed that the distribution of CNT is not uniform along the flow direction, which can significantly affect the properties of microparts. The thermal properties of PP and PP/CNT composites as well as corresponding microparts were investigated using differential scanning calorimetry and thermogravimetric analysis, respectively. Moreover, the mechanical properties of microparts were evaluated by nanoindentation analysis. Multicycling measurements indicated that the mechanical properties of microparts are both depth and location dependent. Both the hardness and elastic modulus increased with corresponding filler loading concentration of CNT below 3 and 7 wt%, respectively. Above those concentrations, both properties decreased with an increase of CNT concentration. This could be related to the state of filler distribution within the microparts.