Improved thermal conductivity of epoxy resins using silane coupling agent‐modified expanded graphite

Abstract

AbstractA silane coupling agent was used to modify the surface of expanded graphite (EG), which was subsequently used as a thermally conductive filler to fabricate diglycidylether of bisphenol‐A (DGEBA)/EG composites with high thermal conductivity via hot blending and compression‐curing processes. The surface characteristics of silane coupling agent‐modified EG (Si@EG) were characterized by a variety of analytical techniques. The effects of the Si@EG content on the thermal conductivity, thermal stability, impact strength, and morphology of the DGEBA/Si@EG composites were investigated. The results revealed that the addition of 80 wt.% Si@EG increased the thermal conductivity of the composites from 0.17 to 10.56 W/m K, which was 61.1 times higher than that of pristine DGEBA. The initial decomposition temperature of the composite containing 80 wt.% Si@EG was 60.6°C higher than that of pristine DGEBA. The impact strength of the composites decreased from 2.0 to 0.87 kJ/m2 when the Si@EG content increased from 0 to 80 wt.%. The scanning electron microscopy images of the fractured surfaces revealed that the EG sheets in the DGEBA matrix formed a continuous thermally conductive path at high Si@EG contents.