Mechanical behavior of carboxylic functionalized graphene reinforced polyurethane nanocomposites under static and dynamic loading

Abstract The present work reports formation of polyurethane (PUR) and carboxylic functionalized graphene (COOH‐fG) nanocomposites via solution mixing method and static and dynamic mechanical characterization with dynamic mechanical analysis (DMA), nano indentation, and tensile and compressive testing. Magnetic stirring of the solutions of PUR in N , N dimethylformamide (DMF) and COOH‐fG in DMF was performed for different compositions of filler, 1%, 3%, 5%, 7%, and 10%, which were heated to obtain nanocomposite films followed by injection molding to cast into samples. Uniform dispersion and good intercalation were observed upon characterization by field emission scanning electron microscopy and X‐ray diffraction techniques. DMA showed that the storage modulus improved with increasing frequency of loading, and a linear decrement in the damping factor with an increase in the concentration of filler was observed. The maximum depth of indent in nano‐indentation test showed a decreasing trend, indicating improvement in nanohardness and elastic modulus with an optimum obtained at 5 wt% composition. An improvement in tensile modulus, tensile strength, and toughness, which were more substantial at lower compositions of filler, was observed. An optimum compressive modulus was obtained for 10 wt% of filler due to more resistance provided by graphene plates to compression as compared to PUR.