Effect of graphene nanoplates and multi-walled carbon nanotubes doping on structural and optical properties of polyvinyl chloride membranes for outdoor applications

Incorporation of different ratios (0, 0.25, 0.5, 0.75, and 1 wt%) of graphene nanoplates (GNPs) or multi-wall carbon nanotubes (MWCNTs) within polyvinylchloride (PVC) via casting method has been examined to improve their structural and linear/nonlinear optical performance. The structural study was carried out using an AFM, FTIR, FE-SEM, and XRD. Different surface and intermolecular structural modifications are induced depending on the dispersed nano-filler type in the PVC matrix. FTIR analysis revealed the disappearance of the –OH and C–H bands accompanied by the appearance of new bands related to the C=O and C–O stretching modes with different intensities for PVC/GNPs and PVC/MWCNTs nanocomposites. The linear and nonlinear optical measurements were performed using a double-beam spectrophotometer and the optoelectronic parameters were deduced from the transmission and reflectance spectra. Optical parameters and constants such as the direct and indirect energy gap, single oscillator energy, dispersion energy, ratio of carrier concentration to its effective mass, lattice and infinite frequency dielectric constant, the linear/nonlinear refractive index, and the third-order susceptibility, based on the types and concentrations of the dispersed GNPs or MWCNTs in the PVC matrix are discussed. The solar skin protection factor (SSPF) of PVC/GNPs nanocomposite with 1 wt% of GNPs increased from 0.7 to 13.5%, while the same MWCNTs contents increased SSPF factor to 11.9%. The calculated optical parameters were found to be GNPs and/or MWCNTs wt% dependent due to their different individual properties and geometry. The present work revealed a guide for tuning the PVC optical properties using both types of nano-filler for usage in flexible optoelectronic applications.