"Improved thermal conductivity and dielectric properties of hBN/PTFE composites via surface treatment by silane coupling agent" has a good discussion you might

"Improved thermal conductivity and dielectric properties of hBN/PTFE composites via surface treatment by silane coupling agent" has a good discussion you might read if you were interested in learning more, there are a number of good citations in that paper, the most useful might be "Dielectric properties of surface treated multi-walled carbon nanotube/epoxy thin film composites"