Dynamic mechanical and optical characterization of PVC/fGO polymer nanocomposites

Abstract

This research demonstrates the effect of functionalized graphene oxide (fGO) by γ-aminopropyltriethoxysilane (APTES) on the structural, dynamic mechanical, and optical properties of polyvinyl chloride (PVC) polymer films. XRD analysis is applied to the prepared samples and the formation of GO is confirmed. Raman scattering measurements for GO and fGO samples confirmed the existence of the D band and G band at 1337 and 1598 cm−1. In addition, the ID/IG ratio increased for the PVC/fGO nanocomposite films, indicating that the relative fraction of sp2-hybridized carbon atom was lowered, and the distorted structure of PVC/fGO nanocomposites. Dispersion of fGO in the PVC/fGO composites was also observed using SEM. DMA measurements revealed that the nanocomposite samples exhibit higher storage moduli than pure PVC as the storage modulus for pure PVC at 20 °C is 173 MPa, whereas it is 176, 334, 498, and 920 MPa for 0.1, 0.3, 0.5, and 1.0 wt% fGO loading, respectively. The glass transition of the nanocomposite films from tan (δ) peaks is for PVC 72.69 °C, whereas it is 74.45, 77.53, 81.59, and 89.59 °C for 0.1, 0.3, 0.5, and 1.0 wt% fGO loading, respectively. FTIR spectroscopy was used to identify interaction in PVC/fGO polymer composites, which the peak around 863 cm−1 of pure film shifts to a lower wavenumber ~ 833 cm−1 with the incorporation of fGO, indicating the existence of strong and intramolecular hydrogen bonding between free C–Cl of PVC and amino groups of fGO. The direct optical energy gap (Eopt) decreased from 5.21 to 5.04 eV and Urbach energy (EU) increased with increasing fGO content. The average excitation energy for electronic transitions (Eo), the dispersion energy (Ed), refractive index, dipole strength (f), optical conductivity, and both static and high-frequency dielectric constants are enhanced with increasing fGO content. Finally, the ratio of free carriers to effective mass (N/m*) increased from 3.68 × 1056 to 12.28 × 1056 m−3 kg−1 and plasma frequency (ω) increased with increasing fGO wt%.