Preparation And Properties Of Graphite Nanosheets/Metal Phthalocyanine/Polyvinylidene Fluoride Ternary Composites With High Dielectric Constant

With the advanced technology in the past decades, people have proposed muchmore requirements for the energy-store materials.The preparation of composites withhigh dielectric constant, low dielectric loss balanced with the acceptable heat-stabilityand mechanical properties has played a significant role in the modern industry fields.The common way is to add the conductive particles such as metal ions andferroelectric ceramics with size under100μm into the polymer matrix which hasexceptional stability and processability to prepare heterogeneous composites.Withmore attention and research being implemented towards carbon materials, thegraphites with huge reserves in nature gain its popularity. Compared to the previousfillers, the graphite materials own excellent conductivity and heat stability as well asthe mechanical properties originating from its special dimensional structure. In orderto exploit the advantages of this materials, there will be some treatment on its surfaceto achieve better dispersion in the polymer matrix.In the first part of this article, we choose graphite nanosheets as conductivefillers treated with mixed solution composed of concentrated sulfuric and nitric acidand obtain the acidified graphite nanosheets (AGS) with size about10μm. Then thepolyvinylidene fluoride matrix was selected and added with the conductive filles toprepare GNS/PVDF and AGS/PVDF composites via solution-mixing andmelt-molding method. The AGS fillers presented a much stronger interaction and amuch better dispersion within the PVDF matrix which were confirmed by the highdielectric constant of AGS/PVDF composites compared with that of GNS/PVDFcomposites. With further experiment, the metal phthalocyanine was introduced in thecomposite system to prepare AGS/Pc/PVDF three-phase composites. The dielectricloss was significant decreased by the incorporated Pc while the dielectric constant hadmaintained at a relatively high standard (327.0.63,10kHz). But the increasing contentof Pc will jeopardize the dielectric properties with the soaring dielectric loss andslightly improvement in dielectric constant. The second part of this paper is focused on the properties of fillers in situ coatedAGS@Pc. Compared in the morphology and the heat stability, the AGS@Pc via insitu coating procedure possessed a firmer coating structure than the AGS/Pc formedthrough solution adsorption method. Also the AGS@Pc preferred a strongerinteraction and a better dispersion in the PVDF matrix than the AGS/Pc fillers, whichcould be interpreted that the firm coating structure prevented Pc from dissolving inthe solution or exfoliating from the AGS under the stirring or ultrasonic. Differentseries of AGS@Pc/PVDF composites were prepared and the dielectric properties werediscussed, then. The dielectric constant remained at a relative high level with thedielectric loss constrained in low rang.