Constructing piperazine pyrophosphate@LDH@rGO with hierarchical core-shell structure for improving thermal conductivity, flame retardancy and smoke suppression of epoxy resin thermosets

Abstract

The integration and miniaturization development of electronic devices placed the great demand for epoxy resin (EP) thermosets with excellent thermal management, flame retardancy and electrical insulation. Herein, a multifunctional additive piperazine pyrophosphate@layered double hydroxide@reduced graphene oxide (PPAP@LDH@rGO) with hierarchical core-shell structure was constructed by solvothermal and electrostatic self-assembly methods to meet the above requirements. Profiting from the distinct structure of PPAP@LDH@rGO, the thermal conductivity of EP/PPAP@LDH@rGO reached 0.951 W m⁻¹ K⁻¹ at 7 wt% addition (3 wt% rGO containing), which is 320.8 % increment compared to pristine EP. Meanwhile, when 4 wt% PPAP@LDH@rGO was added, the EP thermoset reached UL-94 V-0 rating during vertical burning tests with the limiting oxygen index of 29.8 % due to the synergistic effect of PPAP, LDH and rGO. The release of hazard products including smoke and carbon monoxide for EP/PPAP@LDH@rGO visibly declined during combustion. Besides, the EP thermosets also well-maintained the electrical insulation and mechanical properties. This work provided an alternative approach for preparing high performance EP thermosets which was suitable to be applied in electronics and electrical fields.