Smoke suppression and thermal conductivity of epoxy resin modified by Al 2 O 3 and hyperbranched flame retardant

In this work, aluminum oxide (Al 2 O 3 ) was added to hyperbranched flame retardant (PTDOB) modified epoxy resin (EP) system to develop a novel EP thermoset (Al 2 O 3 ‐PTDOB/EP) with superior comprehensive performance. Al 2 O 3 ‐PTDOB/EP exhibited excellent flame retardancy, smoke‐suppressing effects, and enhanced mechanical properties due to the crack pinning effects caused by the introduction of Al 2 O 3 . In detail, the limiting oxygen index (LOI) and UL‐94 rating of Al 2 O 3 ‐PTDOB/EP‐3 reached 34.6% and V‐0 rating, respectively. Cone calorimeter test showed that the total heat release, total smoke production (TSP) and average effective heat of combustion of Al 2 O 3 ‐PTDOB/EP‐3 were reduced by 14.5, 27.3 and 19.2% in comparison to PTDOB/EP, respectively. Furthermore, the impact, tensile and flexural strengths of Al 2 O 3 ‐PTDOB/EP‐3 were significantly improved by 16.7 28.4 and 10.7%, respectively, because the addition of Al 2 O 3 provided the carbon layer barrier and crack pinning effect for the EP matrix. Moreover, thermal conductivity of Al 2 O 3 ‐PTDOB/EP was also improved due to the excellent thermal conductivity of Al 2 O 3 , which had broadened its application in the field of electronic packaging.