Role of the interface in determining the dielectric properties of nanocomposites

Abstract

Role of the interface In determining the dielectric properties of nanocompositesAbstract: It has been demonstrated that the electrical breakdown properties of polymer composites can be substantially enhanced when the filler particles are of nanometric dimensions. These benefits are likely related to the mitigation and redistribution of internal charge. Using the example of an epoxy-TiO 2 nanodielectric (and a comparable conventional composite), this contribution seeks to examine this issue from the physical and chemical viewpoint. It is shown that a reduction in free volume cannot be used to explain the dielectric enhancements. The free volume of nanomaterials is actually higher than that of conventional samples. This conclusion is consistent with recent application of electron paramagnetic resonance methods, which have confirmed earlier speculation that the environment associated with the interface is radically changed when the in-filled particulates are reduced to nanometric dimensions and the associated interfacial area is greatly increased. Through examinations of infrared absorption & EPR, the paper provides some speculation on the part played by an interaction zone surrounding the particulate inclusions. The presence of a highly mobile interlayer is thought to be the key to the electrical property changes seen.

The effect of water absorption on the dielectric properties of epoxy nanocomposites

“…Because their length scale is comparable to that of polymer molecules and the high specific area of the particle surfaces within a composite, nanoparticles exhibit novel properties as fillers. Recently, research incorporating various nanoparticles into existing dielectric systems in a cost effective manner has resulted in nanocomposites with improved benefits over conventional filler systems [4][5] [6] [7] [8]. However, the effect of water on nanocomposites is still far from being well established.…”

Free Volume in Molten and Glassy Polymers and Nanocomposites

“…The studies not only collect information on the influence of P and T on the specific volume, density, compressibility, and other derivative properties, but in addition, using an adequate theory, they offer an insight into segmental interactions, segmental packing, the free volume, which in turn affects a host of properties, including thermodynamic equilibrium and nonequilibrium properties, such as cohesive energy density, solubility, viscosity, diffusivity, as well as the solid-state performance (i.e., physical aging, crystallization kinetics, etc.). For binary systems the PVT data analysis yields information about interactions between constituents: the polymeric matrix and entities dispersed in it: gas bubbles [Xie et al, 1992;Higuchi and Simha, 1996;Xie and Simha, 1997;Simha and Xie, 1998;Simha and Moulinié, 2000;Utracki and Simha, 2001b;Li et al, 2008], domains of immiscible polymers [Zoller and Hoehn, 1982;Jain et al, 1982;Maier et al, 1994;Srithawatpong et al, 1999;Utracki and Simha, 2001a], filler particles Simha et al, , 1986Papazoglou et al, 1989;Simha et al, 1989], or nanoparticles [Simha et al, 2001;Utracki et al, 2003;Nelson et al, 2004;Utracki and Simha, 2004;Bamji et al, 2005].…”

Control of interfaces on electrical properties of SiO2–Parylene-C laminar composite dielectrics

“…volume, which is also shown to have a significant positive impact on the electrical properties of the composite dielectrics [4]. In order to store maximum energy, composite dielectrics must operate close to their breakdown limit and be dielectrically polarizable.…”