Dielectric Constant And Mechanical Properties Of Graphene And Graphite Nanoplateles Modified Phenolic Resin

Phenolic resin has been widely used in energy, automobile, electron and electronics after a century development. Taking advantages of excellent properties of graphene, phenolic resin based nanocomposites would have modified properties to meet the challenges from diverse applications. Thermoplastic phenolic resin was used to prepare nanocomposites with graphene and graphtie nanoplatelets(GNP) by melt blending and solution mixing methods, respectively. Silanes, N-(2-aminoethyl)-3-aminopropyl methyl dimethoxy silane(S602) and 3-ureido propyl triethoxy silane(S160), were used as coupling agents to improve the dispersion of graphene. The structure of graphene and the nanocomposites were characterized by X-ray diffraction(XRD), scanning microscopy(SEM), transmission microscopy(TEM), polarizing microscopy(OM), Fourier transform infrared spectroscopy(FTIR). The dielectric, mechanical and thermal properties of the nanocomposites were evaluated by dielectric spectroscopy, dynamic mechanical thermal analysis(DMTA) and thermogravimetric analysis(TGA).The following results were obtained.(1) The nanocomposites with well dispersed graphene at 0.5 % weight loading were prepared by melt blending method. Silanes could improve the dispersion of GNP in solution, and the nanocomposites with 0.5 % and 1.0 % GNPs were obtained.(2) Graphene and GNP could enhance the dielectric constant of the nancomposites. A dielectric constant as high as 39.8 at a frequency of 10 Hz was achieved for S160 modified nanocomposites with 1.0 % GNP, a 542 % increase in comparison to phenolic resin.(3) The mechanical properties of phenolic resin were improved with addition of graphene and GNP. The storage modulus at 150 ℃ nanocomposites with 0.5 % graphene was 67 % higher than that of pure resin.(4) Graphene/phenolic resin nanocomposites showed better thermal stability and less char residue than phenolic resin. However, GNP based nanocomposites showed higher char residue and better stability of macro-chains instead of impaired initial stability.