Chemistry associated with natural rubber-graphene nanocomposites and its effect on physical and structural properties

Thermally reduced graphene oxide (TRG) was incorporated into dry natural rubber (NR) an important industrial crop, by mechanical melt mixing method. Dramatic improvement in modulus (282%) and O2 gas barrier properties (175%) as compared to neat NR, was observed even at low loading (3% w/w) of TRG. The effect of morphology on physical properties of NR-TRG composites was evaluated and it was observed that the morphology of the resulting composites was highly beneficial for gas barrier applications. The dispersion of TRG platelets in the NR matrix and the possible chemical interactions between NR and TRG platelets were evaluated by high resolution transmission electron microscopy (TEM), Fourier transform spectroscopy (FT-IR), Raman spectroscopy, and X-ray studies. It was concluded that 3% w/w of TRG filled NR is the best composition as compared to other compositions (0.5% w/w, 2% w/w) in terms of stiffness and barrier applications. The improved physical properties could be correlated with the morphology and the crosslink density of the nanocomposite samples. The extent of reinforcement of the TRG filler in the NR matrix was evaluated using Kraus theory and Mooney-Rivilin equation. In addition, the gas barrier properties of graphite, graphite oxide, and TRG filled NR nanocomposites were also discussed and compared. Finally, the experimental barrier properties were correlated with the permeability models of Neilson and Bharadwaj.