Designable core–shell graphite particles for thermally conductive and electrically insulating polymer composites

Abstract

Electrically insulating graphite particles were prepared by coating graphite with electrically insulating materials via a two-step mechanical mixing process. Graphite particles were treated with a binder in the 1^st mixing process and coated with an electrically insulating particle in the 2^nd mixing process under high shear forces within a short processing time (below 1 min). Micron-sized graphite particles were successfully coated with various inorganic particles of appropriate particle diameter. Talc and boron nitride exhibited good affinities with graphite and formed effective coating layers to render reliable electrical insulation. Graphite coated with talc and boron nitride exhibited a high volume resistivity, greater than 10⁹ Ω cm. The insulating property was retained even after compounding and moulding the coated graphite particles with a polymer. The two-step coating process under high shear forces is a promising method for production of coated graphite particles.