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With the continuous miniaturization and integration of electronic devices, polymeric composites with high dielectric constant and low loss have received more and more attention from the field of research. In this work, a novel chemical modification method to fabricate a three-dimensional filler structure consisting of graphene oxide and carbon nanotube (CNT-g-GO) was proposed. Then this filler was introduced into acrylic resin elastomer (AE), and an approach of solution casting combined with hot pressing was used to fabricate the composite films, besides the physical blending composite films of graphene oxide, carbon nanotube and acrylic resin (CNT/GO/AE) were also prepared for a comparison. Results show that the composite containing a volume fraction of 6.72 vol% CNT-g-GO exhibits a dielectric constant of 204.3 and a dielectric loss of 0.16 at 100H Z. The hybrid filler of CNT grafted GO further improves the breakdown strength of composites below the 4.5 vol% filler addition. Furthermore, the origin of the dependence of dielectric loss factor on the frequency at the low frequency was studied with a theoretical model, additionally the mechanism on that enhanced interfacial interaction can more effectively influence the dielectric relaxation behaviors of composites was investigated according to Cole-Cole theoretical model. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Using the graphene decorated with PS-DMC as the conductive filler and acrylic resin as the polymer matrix to prepare a novel dielectric composite. • PS-DMC improves the dispersion of the filler in the matrixand thus improve the dielectric properties of composites. A high performance composite based on acrylic resin elastomer (AE) with a low dielectric loss and a high dielectric constant was prepared through introducing hybrid filler of chemically reduced graphene oxide (RGO) decorated with polystyrene cationic microspheres (PS-DMC) (referred to the composite here as PS-RGO/AE). PS-DMC can not only improve the compatibility between the filler and the matrix so that the filler is uniformly dispersed in the matrix to increase the dielectric constant of the composites, but also can be used as an insulating layer to reduce leakage current and reduce the dielectric loss of the composites. The dielectric constant of 2.43 vol% PS-RGO/AE is 194 at 100 Hz, which is 2.40 times that of the 1.55 vol% RGO/AE (81). Moreover, the dielectric loss of 2.43 vol% PS-RGO/AE composite still maintains at a low level (0.29 at 100 Hz), which is lower than that of 1.55 vol% RGO/AE composite (1.16 at 100 Hz). The higher dielectric constant of PS-RGO/AE composites is attributed to enhanced micro capacitors effect and Maxwell-Wagner-Sillars effect through the uniform dispersion of PS-RGO in the AE matrix and the formation of more interfaces. [ABSTRACT FROM AUTHOR]

Bimodal network composite was prepared using a two-step method containing graphene modified by γ-(2, 3-epoxypropoxy) propyl trimethoxysilane (KH560), short chain poly(dimethyl siloxane) (C S -PDMS) and long chain poly(dimethyl siloxane) filled with treated fumed silica (C L -h-PDMS). A series of composites with different filler contents (including reduced graphene oxide and reduced graphene oxide grafted with KH560, referred to rGO and KrGO, respectively) were prepared to explore their percolation thresholds (fc). We discover that the dielectric constant and loss of 1.32 vol% KrGO/h-PDMS composite were 18.8 and 0.13 at 102 Hz before fc , respectively, which was 2.1 and 0.12 times that of rGO/h-PDMS, and 6.6 and 2.1 times that of pure h-PDMS. The origin is that KH560 insulting layer increases the interlayer distance of graphene sheets to cut down the leakage current. In addition, the modulus of 1.32 vol% KrGO/h-PDMS is less than 3 MPa. Image 1 • Using a two-step method to fabricate poly(dimethyl siloxane) bimodal network composite. • Graphene was grafted with KH560 as insulating layer to improve its dispersion which enhanced the MWS effect. • A comparison among different kinds and contents of fillers is shown here. • From this work, percolation thresholds of composites are identified. • The graphene-polymer percolative composites with excellent dielectric properties was acquired. [ABSTRACT FROM AUTHOR]