Polyethylene Terephthalate/Trimellitic Anhydride Modified Graphene Nanocomposites

Graphene was modified with trimellitic anhydride groups, and its polyethylene-terephthalate-based (PET-based) nanocomposites were prepared by melt-mixing. Percolation thresholds observed from changes to the electrical conductivity and storage moduli of nanocomposite melts suggest that the dispersion levels of unmodified graphene and those of modified graphene in PET matrix were the same. An enhancement of G' and unexpectedly higher [eta] for modified graphene at low concentration suggest that PET chains were grafted on the graphene surface creating a coupled network via covalent bonding. The bulk mechanical properties of amorphous nanocomposites were evaluated by tensile-testing. The nanocomposites with modified graphene also displayed an enhanced Young's modulus as well as higher elongation compared to nanocomposites prepared with unmodified graphene. Differential scanning calorimetry, Fourier-transform infrared spectroscopy, and Raman spectroscopy results obtained on stretched nanocomposites suggest that both strain-induced orientation and strain-induced crystallization were suppressed by the modified graphene.