Crystallization kinetics and interfacial behaviors of polypropylene composites reinforced with multi-walled carbon nanotubes

In this work, the carbon nanotubes (CNTs) were reinforced with polypropylene (PP) matrix resins to improve the electrical, thermal, and mechanical properties of CNTs/PP composites in different contents of 0, 1, 2, 3, and 5 wt.%. The volume resistivity was measured to discover the percolation threshold of the composites. The crystallization kinetics, organizations, and microstructures of CNTs/PP composites were investigated with differential scanning calorimeter (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses, respectively. The Raman spectroscopy was also performed to obtain information on the CNTs/PP interactions. As a result, the volume resistivity was decreased with increasing the CNT content that could be governed in a percolation-like power law with a relatively low percolation threshold. And the crystallization exothermic peak shifted to a higher temperature, and the overall crystallization time was reduced by the increment of CNT content. Also, the nucleant of CNTs affected the crystallization of PP, but was not linearly dependent on the CNT content that meant a saturation of the nucleant effect at low CNT content.