Polycarbosilane-derived silicon carbide-functionalized multi-walled carbon nanotubes and influence on the polyethersulfone nanocomposites

An approach to enhance the dispersion of multi-walled carbon nanotubes (MWCNT) within a polymer matrix is reported. MWCNT surface was modified with a second type of particle, which constitutes a third phase. MWCNT were modified with polycarbosilane-derived silicon carbide (SiC) particles. X-ray diffraction confirmed the formation of β-SiC particles. At a loading level of 1.5 wt%, a fine dispersion of MWCNT throughout the polyethersulfone (PES) was observed by scanning electron microscopy (SEM), but at a higher loading (2.5 wt%), agglomerates of carbon nanotubes were observed. At 2.5 wt% loading, the incorporation of SiC-modified MWCNT in PES showed a homogeneous dispersion of carbon nanotubes throughout the matrix as confirmed by SEM and transmission electron microscopy (TEM). TEM analysis also confirmed the synergistic interactions and improved dispersion of MWCNT within the polymer matrix. Incorporation of SiC-modified MWCNT (SiC-MWCNT) significantly improved the mechanical and thermal properties of PES composites compared to pure PES and a composite containing an equal amount of unmodified MWCNT. The increased quality and improved state of dispersion in the case of a SiC-MWCNT-filled composite can be correlated to an increase of electrical resistivity.