Research Of Dielectric Properties In Nanocomposite Based On Core-Shell Model

Nano-composites, with special good properties, were attracting more and more attention of researcher and applied into extensive fields in recent years, especially in insulating materials. Polymer Nano composites refer to polymer with certain weight percent of nano-particles. Average nano-particles size is within 100nm. The feature of nanocomposite with was significantly different from micron-particles, and even some parameters change in reverse directions. Increasing number of researcher hold that it is attributed to the nano-size. Traditional forces in nano-size would lose their dominant position, while some forces similar to colloid chemistry play leading position in determining electromagnetic field. So researchers was attempted to introduce kinds of chemical and physical forces and some other special model to explain the phenomenon of polymer nanocomposite, and among them multi-layered core model integrated various chemical and physical effects, and was accredited by researchers. But how to verify the multi-core model was effective from the mathematical perspective was exigent questions. At the same time establishing the relationship between micro dimensions and macro parameters from the viewpoint of quantization was great helpful for new nanocomposite research and reducing cost and time of new materials development and test.Based on theoretical research, three-layered core model of nanocomposite was bult, and then referring to image obtained by scanning tunneling microscope, nano-particle size and each shell thinckness were etablished. At the process of determination of each shell permittivity three different functions were established to fit with experimental test. According to integration average of each shell interval, each shell permittivity was established. At last physical model of multi-layer core model was established. At the foundation of this model, this paper studied electric field distribution o of the single sphere in electrostatic field at the start point, then equivalent permittivity of N multi-layered nanoparticles under isodense and non-isodense condition. Till then mathematical model of nanocomposite was established and also equal permittivity was obtained. Further this paper adopted COMSOL software to stimulate of established mathematical model. In order to verify the effectiveness of three-layer model, high frequency dielectric spectroscopy of nanoSiO2/low density polyethylene was carried out. Comparative study of calculated result, stimulated result and test result show that three-layered core model of nanocomposite was effect. Further research show that interface permittivity was close to arctangent function, permittivity of interface was decreased with distance increases. And lowering speed was variable and reached maximum; comparative study of isodense and non-isodense condition show that improved mathematical model was more close to test result because of taking isodense condition into consideration; comparative study of multi-layered core model and non-layered model show that three-layered core model was more close to test result, the reason was that multi-layered core model take physical and chemical effect , the high specific surface area of nano-particles and other size effect. This paper was based on theoretical analysis and then the mathematical and physical model were established which was close to test result. Research result of this paper was helpful and guiding role for nanocomposite theoretical research and development.