Insight into the relationship between interfacial structure and thermal conductivity in epoxy resin/Al2O3 composite

Abstract The relationship between interfacial structure and thermal conductivity in epoxy resin/Al 2 O 3 composite is important but is still elusive. Here, we illuminate this issue by investigating the role of four silane coupling agents in thermal conductivity for epoxy resin/Al 2 O 3 composites. The results show that 3‐glycidoxypropyltrimethoxysilane (KH560) is the best silane coupling agent to modify Al 2 O 3 , resulting in the lowest viscosity and the highest thermal conductivity of the epoxy resin/Al 2 O 3 ‐KH560 composite compared with alternative systems. This is attributed to the strong interfacial interaction between Al 2 O 3 ‐KH560 and epoxy resin, as confirmed by the Fowkes model and broadband dielectric spectroscopy. The interfacial thermal resistance between the epoxy resin and Al 2 O 3 is also quantitatively measured via a photothermal radiometry technique. The epoxy resin/Al 2 O 3 ‐KH560 also has the lowest interfacial thermal resistance (1.50 ± 0.02 × 10 −6 m 2 K W −1 ), compared with the other three systems. This study advances the understanding of the relationship between interfacial structure and thermal conductivity in polymer composites. Highlights The relationship between interfacial structure and thermal conductivity in epoxy resin/Al 2 O 3 composite is understood. The interfacial structure is characterized by broadband dielectric spectroscopy. The interfacial thermal resistance is quantitatively measured via a photothermal radiometry technique.