Expanded graphite–epoxy composites with high dielectric constant

Abstract

Composites of an expanded graphite/diglycidyl ether of bisphenol A (DGEBA) were prepared by a simple melt blending method, and their dielectric and mechanical properties were investigated. During observations of fractured surfaces of the composites, the graphite sheets were seen to be homogeneously dispersed in the epoxy matrix. Moreover, the composites presented an enhanced dielectric constant ($ 180) and a low loss factor ($ 0.05) at 50 Hz, suggesting their potential suitability for embedded dielectric applications. The enhanced dielectric constant can be explained by the percolation theory and the relatively low loss factor was attributed to strong interfacial interactions between the polymer molecules and the AOH/ACOOH groups of the expanded graphite, which constrained the orientational polarization of the polarons. Furthermore, dynamic mechanical analysis of the composites showed a restricted macromolecular relaxation and improved mechanical properties.

Ultra‐high dielectric constant of poly(vinylidene fluoride) composites filled with hydroxyl modified graphite powders

“…And the in‐plane Young's modulus and electrical conductivity of graphite is close to those of CNT . Several reports have been published on the dielectric properties of polymer‐based composites containing modified graphite . For example, Min et al fabricated expanded graphite/epoxy composites with a high dielectric constant of 240 and a dielectric loss of 5 at 1kHz .…”

“…For example, Min et al fabricated expanded graphite/epoxy composites with a high dielectric constant of 240 and a dielectric loss of 5 at 1kHz . Xie et al investigated expanded graphite/epoxy composites and found that the composites presented an enhanced dielectric constant (120) and a low loss (0.3) at 1 kHz suggesting their potential suitability for embedded dielectric applications . Xie et al investigated the preparation and dielectric behavior of PVDF composite filled with stearic acid modified graphite nanoplatelet .…”

Effect of Carbon Particles on the Permittivity and Acoustic Performance of Epoxy Compounds

“…When the epoxy resin (epoxy) is cured by the curing agent, it forms three-dimensional network structure inside, which has a good corrosion resistance, excellent mechanical strength, excellent processing performance, low shrinkage characteristics and so on, but also with lower permittivity, which is about 4.6-5.0 1 and hinders epoxy 's practical application of high dielectric constant. Two or more single-phase materials are composited to modify single-phase materials through taking advantage of the complementary of each material 2 .…”

Graphene Nanocomposites Prepared From Blends of Polymer Latex with Chemically Reduced Graphite Oxide Dispersions

“…In the case of the GIC route, graphite was dispersed in concentrated sulfuric acid and nitric acid in a ratio of 4:1. The following thermal expansion at high temperatures led to expanded graphite which was used as a filler in several polymers like polystyrene, polyethylene, poly(propylene), polyamide 6, poly(phenylene sulfide), epoxy resin, and more 7–33. The resulting composites based on a conventional melt compounding process exhibit a good dispersion of expanded graphite resulting in low rheological or electrical percolation threshold and increased stiffness.…”