| Abstract: | Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electrostatic self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabri-cated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲ was 15 wt％,λ value of the BNN-30@BNNS-Ⅲ/E-44 composites was up to 0.61 Wm-1K-1,increased by 2.8 times compared with pure E-44(λ=0.22Wm-1K-1),also higher than that of the 15 wt％BNN-30/E-44(0.56Wm-1K-1),15wt％BNNS/E-44(0.42 Wm-1K-1),and 15 wt％(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 Wm-1K-1)composites.The λ in-plane(λ∥)and λ cross-plane(λ⊥)of 15 wt％BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated compos-ites significantly reached 2.75 Wm-1K-1 and 1.32 Wm-1K-1,186.5％and 187.0％higher than those of Si-GFs/E-44 laminated composites(λ∥=0.96Wm-1K-1 and λ⊥=0.46Wm-1K-1).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲ fillers were conducive to accelerating heat flow transfer.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,sur-face&volume resistivity of 51.3 kV,23.8 kVmm-1,3.7×1014 Ω&3.4×1014 Ω.cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(ε of 4.92 and tanδ of 0.008)and terrific thermal properties(Tg of 167.3℃and THRI of 199.2℃). |
