Enhanced thermal conductivity and mechanical property of flexible poly (vinylidene fluoride)/boron nitride/graphite nanoplatelets insulation films with high breakdown strength and reliability

Owing to the integration of power electronic devices and the development of flexible devices, demands for high quality thermal conductive composites have substantially increased. Thus highly flexible poly (vinylidene fluoride)/boron nitride (i.e. PVDF/BN-x) composite films were prepared in this work, and a low quantity of graphite nanoplatelets (GNP) was added to simultaneously improve the thermal and mechanical properties of the film (i.e. PVDF/BN-30/GNP-y). The synergistic effect of the two fillers has been discussed, and results show that the thermal conductivity of PVDF/BN-30/GNP-2.5 reaches up to 0.720 Wm(-1) K-1 compared with 0.634 Wm(-1) K-1 of PVDF/BN-30. And the tensile strength is also increased from 12.43 MPa to 20.21 MPa, which has been improved by 63%. In addition, the experiment results validate that the films possess high electrical insulation and satisfactory breakdown strength, which proves its applicability to high-voltage environment. Besides, the thermal conductivity of films can be preserved after 300 thermal shocks with extreme temperature changes. This study provides a kind of flexible thermal interface material with excellent comprehensive properties for application in field of power electronics.