Synthesis of polyethylene glycol-grafted graphite and effect of its loading on properties of natural rubber composites

Modified graphite has attracted considerable interest over recent years due to its surface functionality and better dispersibility with polymeric materials. Incorporation of a small quantity of modified graphite filler into polymer can create novel composites with improved properties. In this study, polyethylene glycol (PEG) was grafted onto the graphite surface in the presence of maleic anhydride (MAH). The PEG-grafted graphite (PEG-g-Graphite) was characterized via Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), and the analysis proved that PEG was successfully grafted onto the graphite surface. Subsequently, natural rubber (NR) composites were prepared by varying the PEG-g-Graphite loading from 0 phr (parts per hundred rubber) to 10 phr at 2 phr intervals. The 10 phr PEG-g-Graphite filled NR composite showed an increment in scorch time and cure time in comparison to the NR composite prepared without PEG-g-Graphite (control). Further, heat resistance of the PEG-g-Graphite/NR composites prepared with 8 and 10 phr loadings of PEG-g-Graphite was at a high level. Due to sheet resistance, values of the 10 phr loading of PEG-g-Graphite and the control composites were 2 × 10⁵ and 3.9 × 10⁷ ohms/square, respectively. The NR composite prepared with 10 phr loading of PEG-g-Graphite could be suitable for high electrical conductive polymeric applications.