Yixin Han, Xuetao Shi*, Shuangshuang Wang, Kunpeng Ruan, Chuyao Lu, Yongqiang Guo and Junwei Gu*. Nest-like hetero-structured BNNS@SiCnws fillers and significant improvement on thermal conductivities of epoxy composites. Composites Part B-Engineering, 2021, 210: 108666. 2019IF=7.635.（1区材料科学Top期刊）

(https://doi.org/10.1016/j.compositesb.2021.108666)

AbstractSilicon carbide nanowires (SiCnws) were in-situ grown on boron nitride nanosheets (BNNS) to construct a novel kind of nest-like hetero-structured BNNS@SiCnws thermally conductive fillers from natural bamboo leaves and tetraethyl orthosilicate (TEOS) by means of ultrasonic impregnation, sol-gel followed by carbothermic reduction. Then, the thermally conductive & electrically insulating BNNS@SiCnws/epoxy composites were prepared via blending-casting method. When the amount of BNNS@SiCnws-II (65/35, wt/wt) was 20 wt%, BNNS@SiCnws/epoxy composites presented the optimal overall performances. Thermal conductivity coefficient (λ) of BNNS@SiCnws-II (20 wt%) /epoxy composites increased from 0.22 W/mK of pure epoxy matrix to 1.17 W/mK, higher than that of SiCnws/epoxy (0.72 W/mK), BNNS/epoxy (0.82 W/mK) and (BNNS/SiCnws)/epoxy composites (direct mixing BNNS/SiCnws, 65/35, wt/wt 0.76 W/mK) with the same filler concentration of 20 wt%. Meanwhile, BNNS@SiCnws/epoxy composites presented excellent heat transfer/heat dissipation efficiency, due to synergistic effect of the “line-to-surface” hetero-structure of SiCnws and BNNS, which could significantly improve the formation probability of the thermally conductive paths. Furthermore, the BNNS@SiCnws/epoxy composites possessed favorable electrical insulation, thermostability and ideal mechanical properties. Furthermore, the related surface & volume resistivities, the electric breakdown strength, the glass-transition temperature, the heat resistant index, the flexural strength as well as the impact strength of BNNS@SiCnws-II (20 wt%)/epoxy composites reached to be 3.7×1015 Ω, 5.17×1015 Ω·cm, 22.1 kV/mm, 126.7 oC, 185.5 ^oC, 75.7 MPa and 8.2 kJ/m², respectively.

本文以天然竹叶为生物质碳源结合正硅酸乙酯（TEOS，硅源），通过超声浸渍-溶胶凝胶-碳热还原法在氮化硼纳米片（BNNS）上原位生长碳化硅纳米线（SiCnws）构筑制备“鸟巢状”异质结构BNNS@SiCnws导热绝缘填料，进而与环氧树脂基体共混复合-浇注成型制备BNNS@SiCnws/环氧树脂导热绝缘复合材料。结果表明，当BNNS@SiCnws-II质量分数为20 wt%时，BNNS@SiCnws-II/环氧树脂导热绝缘复合材料具有最佳的综合性能。其热导率（λ）从纯环氧树脂的0.22 W/mK提升到1.17 W/mK，均高于相同质量分数（20 wt%）的SiCnws/epoxy（单一SiCnws，0.72 W/mK）、BNNS/epoxy（单一BNNS，0.82 W/mK）和（SiCnws/BNNS）/epoxy（直接共混复合SiCnws和BNNS，0.76 W/mK）导热绝缘复合材料的热导率，且具有优越的传热/散热效能，主要归因于BNNS@SiCnws-II能充分发挥SiCnws和BNNS“线-面”异质结构的协同作用，显著提升导热通路的形成概率。此时BNNS@SiCnws-II/环氧树脂导热绝缘复合材料具有优异的电绝缘性能、热稳定性以及理想的力学性能，其表面电阻率（ρs）、体积电阻率（ρv）、电击穿强度（Eb）、玻璃化转变温度（Tg）、耐热指数（THRI）、弯曲强度和冲击强度分别为3.7×1015 Ω、5.17×1015 Ω·cm、22.1 kV/mm、126.7^oC、185.5^oC、75.7 MPa和8.2 kJ/m²。