Glass fiber-reinforced epoxy composites with high thermal conductivity, flame retardancy and mechanical strength

Abstract

Fiber-reinforced epoxy resins (FREPs) have shown broad application prospects because of their excellent comprehensive properties, but their poor thermal conductivity and lack of flame retardancy also restrict their usage in many fields. To solve these problems, DOPO-GL-DCDA was selected as a flame retardant, tannic acid-modified BN and Al₂O₃ were selected as fillers to improve the thermal conductivity of the epoxy thermosets simultaneously, and glass fiber-reinforced epoxy composites (GFREPs) were subsequently prepared by combining an epoxy-filler system with glass fibers (GFs) or modified glass fibers (mGFs). The obtained GFREP revealed excellent comprehensive properties, including flame retardancy, thermal conductivity and mechanical properties. Specifically, the thermal conductivities of EP/40 %(Al₂O₃ + BN)/GF and EP/40 %(Al₂O₃ + BN)/mGF were 0.638 and 0.609 W·m⁻¹·K⁻¹, respectively. Additionally, EP/40 %(Al₂O₃ + BN)/mGF had an LOI of 56.0 % and a V-0 rating in the UL-94 vertical burning test. Compared with those of EP, the heat release rate (HRR), total heat release (THR) and total smoke production (TSP) of EP/40 %(Al₂O₃ + BN)/mGF were reduced by 90.9 %, 90.6 % and 80.2 %, respectively. Moreover, the mechanical properties, including the tensile and impact strengths, of EP/40 %(Al₂O₃ + BN)/mGF reached 239.2 MPa and 77.4 kJ/m², respectively. In summary, the prepared GFREP combines a series of excellent comprehensive properties with the maintenance of low dielectric loss, which shows wide potential in electronic and electrical applications.