Crystallisation behaviour and morphological characteristics of poly(propylene)/multi-walled carbon nanotube nanocomposites

The objectives of this article are to study the crystallisation behaviour and morphology of melt compounded nanocomposites of poly(propylene) (PP) and multi-walled carbon nanotubes (MWNTs). A PP matrix containing different contents of 0, 1, 2, 4 and 8 wt% of the MWNTs nanofiller was prepared for this investigation. Studies using a differential scanning calorimetry and a wide angle X-ray diffraction indicated that the MWNTs promoted heterogeneous nucleation. The nucleant of the MWNTs affected the crystallisation of the PP, but was not linearly dependent on the MWNT content which meant a saturation of the nucleant effect at low carbon nanotube content. The relative amount, crystallite size and distribution of different crystallites in the PP varied because of the addition of the MWNTs, which affected the final properties of the nanocomposites. Meanwhile, the degree of crystallinity of the PP exhibited an increasing trend with the addition of MWNTs, followed by moderate decreases at higher content. Continuous scanning electron microscopy observations indicate that the nanotubes are well dispersed in the PP matrix at low content of MWNTs. Each nanotube is covered by a layer of PP molecules.