Highly thermally conductive carbon nanotubes pillared exfoliated graphite/polyimide composites

In this work, carbon nanotubes pillared grew on exfoliated graphite by the microwave-assisted method is utilized as thermally conductive fillers (CPEG) in polyimide (PI) to fabricate CPEG/PI thermally conductive composites with the combining ways of “in-situ polymerization, electrospinning, lay-up, and hot-pressing”. The prepared CPEG/PI composites realized the maximum thermal conductivity (λ, 1.92 W m⁻¹ K⁻¹) at low CPEG amount (10 wt%), much higher than that of pure PI (0.28 W m⁻¹ K⁻¹). The λ of CPEG/PI composites show almost no change after 1000 cycles of heating and cooling at the temperature of 25−100 °C. The finite element analysis simulates the nano-/microscale heat transfer in CPEG/PI composites to reveal the internal reason of the λ enhancement. The improved thermal conductivity model and empirical equation could better reflect the actual λ change trend of CPEG/PI composites. The actual application test shows the CPEG/PI composites could significantly reduce the operating temperature of the CPU in mobile phone.