Comparative study on the electrical, thermal, and mechanical properties of multiwalled carbon nanotubes filled polypropylene and polyamide 6 micromoldings

In this work, a series of carbon nanotubes filled polypropylene (PP/CNT) and polyamide 6 (PA6/CNT) composites were prepared by melt blending and subsequently molded by compression molding and microinjection molding (mu IM), respectively. Electrical conductivity results indicate that the percolation threshold of corresponding microparts shifted to higher filler concentrations when compared with that of compression molded counterparts, suggesting the prevailing shearing conditions in mu IM is unfavorable for the construction of conductive pathways. In addition, Raman spectral analysis shows that there is a preferential alignment of CNTs along the flow direction of microparts. Thermal properties of both melt blended samples and subsequent microparts were evaluated using differential scanning calorimetry and thermogravimetric analysis. The mechanical properties of subsequent microparts are greatly affected by filler concentration, which might be related to the structural change that induced by the state of dispersion of CNTs.