Bio-based Epoxy Composites Demonstrating High Temperature Breakdown Strength and Thermal Conductivity for High Voltage Insulation

The demand for energy-efficient and environmental-friendly power grid construction has made the exploitation of bio-based electrical epoxy resins with excellent properties increasingly important. This work developed the bio-based electrotechnical epoxy resins based on magnolol. High-performance epoxy resin (DGEMT) with a double crosslinked points and its composites (Al₂O₃/DGEMT) were obtained taking advantages of the two bifunctional groups (allyl and phenolic hydroxyl groups) of magnolol. Benefitting from the distinctive structure of DGEMT, the Al₂O₃/DGEMT composites exhibited the advantages of intrinsically high thermal conductivity, high insulation, and low dielectric loss. The AC breakdown strength and thermal conductivity of Al₂O₃/DGEMT composites were 35.5 kV/mm and 1.19 W·m⁻¹·K⁻¹, respectively, which were 15.6% and 52.6% higher than those of petroleum-based composites (Al₂O₃/DGEBA). And its dielectric loss tanδ=0.0046 was 20.7% lower than that of Al₂O₃/DGEBA. Furthermore, the mechanical, thermal and processing properties of Al₂O₃/DGEMT are fully comparable to those of Al₂O₃/DGEBA. This work confirms the feasibility of manufacturing environmentally friendly power equipment using bio-based epoxy resins, which has excellent engineering applications.