Effect of Polypropylene–Grafted–Maleic Anhydride Compatibilizer on the Physical Properties of Polypropylene/Carbon Nanotube Composites

The mechanical, rheological, morphological and thermal properties of a polypropylene (PP) matrix reinforced with single-walled nanotubes (SWNTs) and poly(propylene-grafted-maleic acid) (PP-g-MA) content were investigated by melt processing. PP-g-MA was used as a compatibilizer to promote carbon nanotube dispersion. Compared to uncompatibilized PP/SWNT nanocomposites, the tensile modulus of the material increased considerably when nanotubes and compatibilizer were employed. Furthermore, the Izod impact strength and tensile strength improved when 0.5 wt.% SWNTs and 1 wt.% PP-g-MA were added to the PP matrix. The rheological characterization results revealed that addition of SWNTs increased the storage modulus and complex viscosity at low frequencies. When PP-g-MA was introduced, the complex viscosity and storage modulus further increased. Scanning electron microscopy revealed that the SWNTs were uniformly distributed when low concentrations of SWNTs were employed. In addition, the dispersion and adhesion between SWNTs and the PP matrix were improved when 0.5 wt.% SWNTs and 1 wt.% PP-g-MA were added. The results of differential scanning calorimetry indicated that the addition of SWNTs increased the crystallinity of PP/SWNT nanocomposites.