Effect of functionalization of multiwalled carbon nanotubes with aminated poly(ether sulfone) on thermal and mechanical properties of poly(ether ether ketone) nanocomposites

Multiwalled carbon nanotubes (MWCNTs) were functionalized with aminated poly(ether sulfone) (PES) through the amidation reaction. Characterizations by Fourier transform infrared spectroscopy and X-ray diffraction corroborated the success of grafting reaction. Raman spectra reveal that no further damage occurred after the anchoring of PES to the carboxylated MWCNTs. Transmission electron microscopy shows that PES functionalization resulted in better dispersion of MWCNTs than acid oxidation. Poly(ether ether ketone) (PEEK)/MWCNTs functionalized with PES (PES-MWCNTs) nanocomposites were fabricated by solution-mixing and compression-molding techniques. Thermogravimetric analysis indicates that PES-MWCNTs/PEEK nanocomposites have the highest degradation temperature and thermal stability. Furthermore, noticeable increases in the crystallization and melting temperature as well as in the degree of crystallinity were found from differential scanning calorimetry thermograms, attributed to the strong heterogeneous nucleating role of PES-MWCNTs. Tensile test presents that the attachment of PES to the surface of MWCNTs exceptionally improved the tensile strength and Young's modulus, and obtained moderate elongation at break. Impact toughness test and dynamic mechanical analysis show that the addition of PES-MWCNTs greatly enhanced the toughness and storage modulus of PEEK, respectively. These results are attributed to improved dispersion of PES-MWCNTs and strong interfacial adhesion to matrix, which is evidenced by scanning electron microscopy.