Raman spectra, thermal and mechanical properties of poly(ethylene terephthalate) carbon-based nanocomposite films

Abstract

Poly(ethylene terephthalate) (PET) nanocomposite film with 1 wt % of nanodiamonds terminated with carboxylic groups (PET- NDCOOH), PET nanocomposite film containing 1 wt% of NDCOOH and 0.3 wt % nanographene platelets (PET- NDCOOH-NGP) and a neat PET film were prepared by melt extrusion. Raman spectroscopy was performed in order to establish the interactions between the nanofiller (NDCOOH and nanographene platelets (NGPs)) and polymer matrix. The thermal behaviour of the PET nanocomposites was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mechanical properties were determined by tensile tests performed on strips cut from the prepared films in directions parallel and perpendicular to the direction of film preparation. Raman spectroscopy and DSC results showed that incorporation of NDCOOH and NGPs into the composite enhances crystallinity, inducing the growth of crystals in the polymer matrix. According to TGA results, the addition of NDCOOH and NGP enhanced thermal stability. The results obtained from the tensile strength tests in the longitudinal direction showed that incorporation of NDCOOH particles resulted in matrix plasticization. The increase in stiffness in the transversal direction can be ascribed to interactions between NDCOOH and the PET matrix. The tensile strenght of PET-NDCOOH-NGP nanocomposite film in both directions decreased in comparison to neat PET.