Dielectric properties of epoxy/POSS and PE/POSS systems

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 nonconductive 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) appear 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

Unusual Deviations from Bulk Behavior in Ultrathin Films of Poly(tert-butylstyrene): Can Dead Layers Induce a Reduction of T-g?

info:eu-repo/semantics/publishe

Mechanism of dielectric constant variation of POSS-based organic-inorganic molecular hybrids

10.1021/jp1080753Journal of Physical Chemistry C1145122455-2246