Study On Functionalization Of Graphene Sheets And Its Modification On Properties Of Polymer Materials

Graphene, a novel carbon-based material, has been emerging in recent years, which is theoretically a robust two-dimensional(2D) sp2-hybridized hexagonal honeycomb lattice plane carbon material with excellent thermal, mechanical, optical, electrical and other properties. This new type of promising nanofiller has been widely used for properties modification of polymer materials. Chemical functionalization on graphene has found to be more efficient on improving the properties of polymer materials. In this article, we first fabricated the functionalized graphene sheets and then invesitigated its modification on properties of polymer materials.(1) One kind of functionalized graphene oxide(GO) was simply prepared by a base deposition. The sediment was defined as base-deposited graphene oxide(bdGO). The structure and properties of the bdGO was investigated by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), X-ray diffraction(XRD) and transmission electron microscopy(TEM). The results showed that the bdGO particles exhibited crumpled surfaces, abundant basic groups and good adsorption properties.(2) The effect of bd-GO particles on the thermal stabilization for poly(vinyl chloride)(PVC) was investigated by the Congored test and thermogravimetric analysis. The stabilization mechanism was investigated using UV-visible spectroscopy and nitrogen adsorption-desorption isotherm analysis. The results indicated that the thermal stability of PVC was significantly increased because of the the deactivation of thermally labile structural defects in the PVC chains by the carboxylate and alkoxide moieties of the basic groups in the bd GO particles, and the highly efficient adsorption of the bdGO particles with hydrogen chloride produced during PVC degradation.(3) Another kind of functionalized GO was prepared by the surface reaction with 4, 4-diphenyl methane diisocyanate(MDI) and then quaternary ammonium salts. The final particle which exhibited amphiphilic property was named as AGO. The AGO particles were added in the linear low density polyethylene(LLDPE)/ethylene-vinyl acetate copolymer(EVA) blend. The distribution of the particles in LLDPE/EVA blend was investigated by scanning electron microscopy(SEM). The crystallization and mechanical properties of the LLDPE/EVA/AGO composites were studies by XRD, FTIR, TGA, differential scanning calorimetry(DSC), and universal tensile test. The results showed that the AGO particles were basically distribution at the interface of two polymer phases. The interfacial interaction has been enhanced and the mechanical property of the composites has also been improved.