Candidate Mechanisms Responsible for Property Changes in Dielectric Nanocomposites (original) (raw)

Polymer Nanocomposite Dielectrics – The Role of the

Dielectrics and …, 2005

The incorporation of silica nanoparticles into polyethylene increased the breakdown strength and voltage endurance significantly compared to the incorporation of micron scale fillers. In addition, dielectric spectroscopy showed a decrease in dielectric permittivity for the nanocomposite over the base polymer, and changes in the space charge distribution and dynamics have been documented. The most significant difference between micron scale and nanoscale fillers is the tremendous increase in interfacial area in nanocomposites. Because the interfacial region (interaction zone) is likely to be pivotal in controlling properties, the bonding between the silica and polyethylene was characterized using Fourier Transformed Infra-red (FTIR) spectroscopy, Electron Paramagnetic Resonance (EPR), and X-ray Photoelectron Spectroscopy (XPS) The picture which is emerging suggests that the enhanced interfacial zone, in addition to particle-polymer bonding, plays a very important role in determining the dielectric behavior of nanocomposites.

Role of the interface in determining the dielectric properties of nanocomposites

The 17th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 2004. LEOS 2004.

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 Promise of Dielectric Nanocomposites

Conference Record of the 2006 IEEE International Symposium on Electrical Insulation, 2006

Several research groups worldwide have now been able to document some significant improvements that can be made in the electrical, and other, properties of polymer composites through the incorporation of nanoparticulates. Although it is now becoming clear that the mechanisms responsible for these changes are by no means universal, some of the benefits are substantial and rely on the large interface areas which are inherent in the introduction of materials of nanometric dimensions. By examining a variety of nanomaterials, this contribution seeks to review the property changes that can be brought about and examines the possibilities for commercial applications. This involves not only the electrical properties, but the implications for the attendant mechanical characteristics and the polymer processing necessary for utilization of this emerging breed of dielectric material. In this context, the functionalization of the particulate surfaces to provide preferential coupling to the host polymer will be explored since, by this means, a degree of preferred assembly can be accommodated. Through experimental examples, the use of this technique to tailor the properties of nanodielectrics is illustrated.

Dynamics and dielectric properties of polymer/nanoparticle nanocomposites by dielectric spectroscopy

Dynamics and dielec. properties of nanocomposites based on polymer matrixes and different types of nanoparticles, as studied by several authors, have been reviewed. Studies on nanocomposites based both on thermoplastic (conductive, non conductive and liq. crystals) and thermosetting matrixes are presented, with several types of nanoparticles (ceramic, metallic, metal oxide and others) as fillers. Their effect on dielec. properties and mol. dynamics has been analyzed, underlaying the strong effect of the interfaces on them. Theor. models such as those corresponding to the percolation theory proposed by several authors to quantify those effects are presented and compared, discussing the values and evolution of the fitting parameters.

Tuning of Dielectric Properties of Polymers by Composite Formation: The Effect of Inorganic Fillers Addition

Journal of Composites Science

Polymer blend or composite, which is a combination of two or more polymers and fillers such as semiconductors, metals, metal oxides, salts and ceramics, are a synthesized product facilitating improved, augmented or customized properties, and have widespread applications for the achievement of functional materials. Polymer materials with embedded inorganic fillers are significantly appealing for challenging and outstanding electric, dielectric, optical and mechanical applications involving magnetic features. In particular, a polymer matrix exhibiting large values of dielectric constant (ε′) with suitable thermal stability and low dielectric constant values of polymer blend, having lesser thermal stability, together offer significant advantages in electronic packaging and other such applications in different fields. In this review paper, we focused on the key factors affecting the dielectric properties and its strength in thin film of inorganic materials loaded poly methyl meth acryla...

Effect of nanofillers on the dielectric properties of epoxy nanocomposites

Advances in materials Research, 2012

Epoxy resin is widely used in high voltage apparatus as insulation. Fillers are often added to epoxy resin to enhance its mechanical, thermal and chemical properties. The addition of fillers can deteriorate electrical performance. With the new development in nanotechnology, it has been widely anticipated that the combination of nanoparticles with traditional resin systems may create nanocomposite materials with enhanced electrical, thermal and mechanical properties. In the present paper we have carried out a comparative study on dielectric properties, space charge and dielectric breakdown behavior of epoxy resin/nanocomposites with nano-fillers of SiO 2 and Al 2 O 3. The epoxy resin (LY556), commonly used in power apparatus was used to investigate the dielectric behavior of epoxy resin/nanocomposites with different filler concentrations. The epoxy resin/nanocomposite thin film samples were prepared and tests were carried out to measure their dielectric permittivity and tan delta value in a frequency range of 1 Hz-1 MHz. The space charge behaviors were also observed by using the pulse electroacoustic (PEA) technique. In addition, traditional epoxy resin/microcomposites were also prepared and tested and the test results were compared with those obtained from epoxy resin/nanocomposites.

Comparison of the Dielectric Response of Alumina-Epoxy Composites with Nano- and Conventional Sized Filler

2009

This paper looks at the dierences in dielectric response between epoxy resin com- posites with conventional and nanoscale alumina filler. Host material, namely bisphenol-A epoxy resin, is the same for all samples. Preparation of the samples is described in detail. Both filler types are treated in similar fashion to ensure comparability of the results. An even distribution of the alumina in case of the nanoscale filler was validated by means of transmis- sion electron microscopy. It is shown by means of dielectric spectroscopy how the particle size and preparation influence the material properties. Measurements were performed in a broad frequency range between 0.01 and 10 MHz, for temperatures between -20C and the glass transition temperature of the host material close to 120C. Possible explanations for the witnessed behavior are presented and the contributing factors discussed.