In our previous work, we studied the physical characteristics (particle size, surface treatment, etc.) of huntite/hydromagnesite mineral in order to be employed as a flame retardant filler. With this respect, electrical properties of the mineral reinforced polymeric composites were investigated in this study. After grinding of huntite/hydromagnesite mineral to the particle size of 10？μm, 1？μm, and 0.1？μm, phase and microstructural analyses were undertaken using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The ground minerals with different particle size and content levels were subsequently added to ethylene vinyl acetate copolymer (EVA) to produce composite materials. After fabrication of huntite/hydromagnesite reinforced plastic composite samples, they were characterized by using Fourier transform infrared (FTIR) and SEM-EDS. Electrical properties were measured as a main objective of this paper with Alpha-N high resolution dielectric analyzer as a function of particle size and loading level. Dielectric constant, dissipation factor, specific resistance, and conductivity of the composite materials were measured as a function of frequency. On the other hand, conductivity of Ag-coated and uncoated polymeric composite materials was measured. It was concluded that the electrical properties of plastic composites were improved with reducing the mineral particle size. 1. Introduction Despite significant advances in synthesis and characterization of polymers, a correct understanding of polymer molecular structure did not emerge until the 1920s. Before then, scientists believed that polymers were clusters of small molecules (called colloids), without definite molecular weights, held together by an unknown force. In 1922, Hermann Staudinger proposed that polymers consisted of long chains of atoms held together by covalent bonds, an idea which did not gain wide acceptance for over a decade and for which Staudinger was ultimately awarded the Nobel Prize [1]. A polymer can be described as macromolecule composed of repeating structural units typically connected by covalent chemical bonds [2]. A large and growing number of commercial polymers are composed of different types of unit attached together by chemical covalent bonds. They are known as copolymers and can comprise just two different units or three and so on. It is one of the common strategies used by molecular engineers to manipulate the properties of polymers to gain just the right combination of properties for a specific application [3]. Due to their low
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