Preparation of sulfur-doped graphenes by Yucel's method and their corresponding polylactide-based nanocomposites

In this study, S-doped graphene (SG) powders were produced in one-step green and environmental-friendly, quick, and cheap route of Yucel's method. Different sulfur functional groups were formed on graphene surfaces by changing the anodic potential range and were first used to prepare SG/polylactide (PLA) nanocomposites. The influence of applied potential on the structural properties of SG powders was explored through cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and BET surface area analysis. S-doped graphenes were subsequently melt mixed with polylactide at low contents of 0.1 and 0.5 wt% using a twin-screw extruder. The interaction of SGs functional groups with PLA and its effect on the nanocomposites' final morphological, thermomechanical, and tensile properties was then studied. It was revealed that the tensile strength and modulus of the nanocomposites were noticeably increased with the addition of such low SGs contents. The applied potential and hence the structural properties of SGs differently influenced the final tensile properties of the nanocomposites. A maximum enhancement of around 100% in tensile strength was observed using only 0.1 wt% SG produced at the potential range of −1.5 and 2.3 V.