Chemical functionalization of graphene oxide by a hindered amine stabilizer and evaluation of the product as a UV-stabilizer for polypropylene

Abstract

The present work was devoted to synthesis of a novel UV-stabilizer based on graphene oxide for polypropylene. Hence, we grafted a hindered amine compound on graphene oxide through an amidation reaction. Fourier transform infrared (FTIR) spectroscopy and thermo-gravimetric analysis confirmed the grafting reaction. Also, X-ray diffraction together with scanning electron microscopy showed that the grafting reaction transforms the compact layered structure of graphene oxide into finer aggregation of loosely connected particles. Polypropylene film samples containing either of graphene oxide and the functionalized graphene oxide were prepared by solution mixing/anti-solvent precipitation followed by compression molding. Transmission electron microscopy showed significantly better dispersion of the modified graphene oxide in the polymer matrix compared to the pristine graphene oxide. Afterwards, the film samples were exposed to an artificial sunlight at 25 °C. It was proved by FTIR spectroscopy and tensile test that the modified graphene oxide at a concentration of 0.5 wt. % can efficiently retard the rate of the photo-oxidation of PP.