Experimental, Simulation and Theoretical Insights into Anisotropic Thermal Conductivity of Epoxy Nanocomposites with Diverse Carbon Nanostructures

Understanding and optimizing thermal conductivity in epoxy-based composites is crucial for efficient thermal management applications. This study investigates the anisotropic thermal conductivity of a tetra-functional epoxy resin filled with low concentrations (0.25–2.00 wt%) of carbonaceous nanofillers: 1-D multiwall carbon nanotubes (MWCNTs) and 2-D exfoliated graphite (EG) nanoparticles. Epoxy formulations incorporating MWCNTs exhibit a ~60% increase in in-plane thermal conductivity (λI-p dir.) compared to the unfilled resin, with negligible changes in the through-plane direction (λT-p dir.). Conversely, EG nano-particles enhance thermal conductivity in both directions, with a preference for the in-plane direction, achieving a ~250% increase at 2 wt%. In light of this, the graphene-based fillers establish a predominant thermal transport direction in the resulting nanocomposites due to their layered structure, whereas MWCNTs create unidirectional thermal pathways. Experimental measurements, conducted using the Transient Plane Source (TPS) method, were complemented by multiphysics simulations in COMSOL and theoretical studies based on the theory of thermal circuits to explain the observed phenomena and justify the experimental findings. The TPS results reveal distinct behaviors depending on the nanofiller geometry. This integrated approach, combining experiments, theoretical analyses, and simulations, demonstrates the potential for tailoring the thermal properties of epoxy nanocomposites. These insights provide a foundation for developing advanced materials optimized for efficient thermal management in high-performance systems.