Dielectric Properties of Epoxy/POSS and PE/POSS Systems

Abstract

In many applications in electronic, power and high voltage engineering, there is a need to improve the electrical properties of existing insulation systems and/or to develop novel insulation materials with properties more suitable with the changing requirements, particularly in the electrotechnical area. During the last few decades, a considerable attention has been given to the possible use of polymeric nanocomposites systems, usually a non-conductive polymer containing nanometric inorganic fillers, as a replacement to the neat polymers offering better electrical and thermal properties. There is almost nowadays a consensus among the scientific community that such property enhancements can only be achieved when the nano-fillers present a reasonably good size dispersion and spatial distribution within the host polymer. However, due to nano-fillers' strong tendency to agglomerate and their generally poor compatibility with commonly-used polymers, to reach optimal dispersions has been found challenging in most cases. In order to improve the polymer/particles compatibility and therefore to avoid agglomeration and poor dispersion problems, polyhedral oligomeric silsesquioxanes (POSS) appears to be a filler of choice since they are by nature nanoscaled molecules bearing built-in functionalities which can be selected according to the chemical nature of the host polymer. This chapter summarizes the investigations that were reported so far on the electrical properties of epoxy/POSS, PE/POSS and PP/POSS systems. The general conclusion is that in the case of polyolefin/POSS composites, nanoscale dispersion was found to be hard to reach despite the selection alkyl-type POSS and the dielectric properties were not found to be strongly improved while in the case of epoxy/POSS systems, the selection of appropriate POSS compounds and a carefully chosen resin/additive/hardener ratio allow nanoscale dispersion accompanied with noticeable improvements of the dielectric properties.

Progress in the Synthesis of Bifunctionalized Polyhedral Oligomeric Silsesquioxane

“…In recent years, inorganic-organic hybrid materials with carbon nanotubes [1][2][3][4][5], graphene [6][7][8][9], organosilicons [10][11][12], metal oxides [13,14], and natural polymers [15][16][17] have attracted considerable attention because of their distinctive properties. Among these, the incorporation of polyhedral oligomeric silsesquioxane (POSS) has attracted attention because of its unique frame structure and the resulting chemical and physical properties, including high thermal properties [18][19][20], lower crystallinity [21], mechanical properties [22], oxidation resistance, and very good dielectric properties [23,24]. Hence, it has been widely used in preparing polymer hybrids and polymer composites in many areas, including optics [25], electronics, ionic liquids [26], mechanics [27], energy [28], environment [29], biology [30], smart coatings [31,32], fuel [33], solar cells [34], catalysts [35,36], sensors [37][38][39], light-emitting devices [40], and medicine [41][42][43]…”