Determination of glass transition temperature of reduced graphene oxide-poly(vinyl alcohol) composites using temperature dependent Fourier transform infrared spectroscopy

In the present work, structural properties of reduced graphene oxide (RGO) synthesized using modified Hummer's method and its composites with Poly(vinyl alcohol) (PVA) fabricated using solution-cast method have been studied. The structural properties of prepared samples have been systematically studied through UV-Visible absorption, Raman, Fourier Transform Infrared (FTIR) and Differential Scanning Calorimeter (DSC) spectroscopy. Infrared spectroscopy indicates the grafting of PVA chains with graphene layer through the formation of H-bonding linkage in the composites. Temperature-dependent FTIR spectra of PVA-RGO composite films were recorded to obtain the glass transition temperature (T-g) and to study its molecular origin. From these spectra the values of T-g were obtained using two-dimensional (2D) mapping of the first derivative of the absorbance intensity with respect to temperature (dA/dT), over the space of wavenumber and temperature. The value of T-g obtained for pure PVA increases from 78 degrees C to 92 degrees C after loading 0.5 wt.% of RGO in PVA and can be attributed to the strong H-bonding interaction between polymer chains and grafted solid surface of RGO. These results are in good agreement with those obtained from DSC analysis. This clearly indicates that the thermal behavior of PVA gets modified with loading of RGO. (C) 2016 Elsevier B.V. All rights reserved.