Fundamentals for the compounding of nanocomposites to enhance electrical insulation performance

Abstract

Although it is undeniable that the promise of enhanced dielectric properties through the use of nanotechnology has generated worldwide interest in nanodielectrics in the last decade, study of the experimental literature indicates that there are numerous inconsistencies in the results obtained. In many instances, it is likely that this is due to a lack of quality control during the formulation of this new class of material. By examining several nanocomposite examples, this contribution seeks to shed some light on the likely causes for these inconsistencies.Through the paramount property of dielectric strength, it is confirmed that poor dispersion and/or agglomeration is often the cause of poor material performance. Examples are provided to show how this can be rectified through the use of particle functionalization and compatibilizers, the use of shear in compounding, and the careful control of moisture. However, good dispersion alone is not sufficient since some of the techniques used may also lead to microcavity formation and other undesirable phenomena. The optimization of nanocomposite compounding is intimately connected with the need to quantify the resulting structure. Consequently, the paper includes a brief discussion of the part played by thermogravimetric and thermal analyses as well as the use of the focused ion beam method to supplement scanning electron microscopy as a viable alternative to (the more difficult) transmission electron microscopy for the evaluation of dispersion and percolation.

Ligand Engineering of Polymer Nanocomposites: From the Simple to the Complex

“…Thus, at the very least, surface modification is required to control dispersion. This control has been achieved repeatedly through ligand engineering , and has been demonstrated directly in nanodielectrics, increasing breakdown strength by up to 50% through the reduction of agglomeration. − Challenges still exist, however, when nanoparticles with short molecule ligands have been scaled up for commercial use. Accordingly, the use of brushes, particularly in thermoplastics, should be more fully explored.…”