PNNL

Abstract

Conductive nanofillers, if integrated in an organized manner, can improve transport properties of polymer matrices without compromising on their light weight. However, the relationship between particle assemblies and transport properties of such nanocomposites, especially the competing effects of connected nanofiller pathway compared to resistances at inter-particle contacts, has not been quantitatively studied. In this work, with the model nanocomposite of maghemite nanoparticles in epoxy, a novel fabrication method has been demonstrated to align nanofillers and control inter-particle contact amount within such nanofiller assembly, using nanoparticle surface functionalization and oscillating magnetic field application. The nanofiller assembly cross-sectional areas were measured by processing microCT images, and compared with the measured electrical and thermal properties of the nanocomposites. In terms of thermal transport, when the nanofiller assembly cross-sectional area was small, the dominance of conductivity pathways was observed up to ~4.7 vol%, while interfacial thermal resistance began to dominate when the nanofiller assembly cross-section area became larger than 2700 µm2.