[Advanced Composites and Hybrid Materials] Flexible thermally conductive and electrically insulating silicone rubber composite films with BNNS@Al2O3 fillers
writer：Han Yan#, Xiaojun Dai#, Kunpeng Ruan, Sijie Zhang, Xuetao Shi, Yongqiang Guo, Huaqiang Cai* and Junw
keywords：thermally conductive
source：期刊
specific source：Advanced Composites and Hybrid Materials
Issue time：2021年
AbstractWith the advent of 5G era, the electronic and electrical industries are in increasingly urgent demand for flexible materials with high thermal conductivity coefficients (λ). In this paper, alumina (Al2O3) was chemically grafted to the surface of boron nitride nanosheets (BNNS) to prepare hetero-structured thermally conductive fillers (BNNS@Al2O3), and two-component room temperature vulcanized silicone rubber (RTV-2SR) was used as the polymer matrix. Then BNNS@Al2O3/RTV-2SR flexible thermally conductive and electrically insulating composite films were prepared by shear-coating. Results of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) showed that the BNNS@Al2O3 hetero-structured thermally conductive fillers with ‘point-plane’ structure were successfully prepared. The BNNS@Al2O3 hetero-structured thermally conductive fillers successfully achieved the synergy of Al2O3 and BNNS, and had more significant improvement on λ than single Al2O3, single BNNS and simply blending BNNS/Al2O3. When the amount of BNNS@Al2O3 was 30 wt% (BNNS/Al2O3, 1:1, wt:wt), the in-plane λ (λ∥) and through-plane λ (λ⊥) of the BNNS@Al2O3/RTV-2SR thermally conductive composite film reached 2.86 W/mK and 0.89 W/mK, 2.8 times λ∥ (1.01 W/mK) and 4.2 times λ⊥ (0.21 W/mK) pure RTV-2SR film, also higher than those of BNNS/RTV-2SR (with single BNNS, λ∥=2.46 W/mK, λ⊥=0.76 W/mK), Al2O3/RTV-2SR (with single Al2O3, λ∥=1.62 W/mK, λ⊥=0.49 W/mK) and (BNNS/Al2O3)/RTV-2SR (with simply blending BNNS/Al2O3, 1:1, wt:wt, λ∥=2.04 W/mK, λ⊥=0.62 W/mK) thermally conductive composite films with the same fillers amount. Meanwhile, the prepared BNNS@Al2O3/RTV-2SR thermally conductive composite film obtained excellent mechanical properties, electrical insulation properties and thermal properties. Its tensile strength, elongation at break, hardness, dielectric constant (ε), dielectric loss (tanδ), volume resistivity (ρv), glass transition temperature (Tg) and heat resistance index temperature (THRI) respectively reached 0.84 MPa, 175%, 27 HA, 3.89, 0.0088, 5.76×1011 Ω·cm, -40.1oC and 185.3oC. This work can provide a new idea for the preparation of hetero-structured thermally conductive fillers and flexible thermally conductive and electrically insulating composite films.
隨著5G時代的到來，電子電氣行業對于具有高導熱系數（λ）的柔性導熱材料的需求日益迫切。本文通過化學接枝法將氧化鋁（Al2O3）接枝到氮化硼納米片（BNNS）上，制備了一種具有“點-面”結構的二元異質結構導熱填料（Al2O3@BNNS），然后以雙組份室溫硫化硅橡膠（RTV-2SR）為基體，通過剪切涂覆制備了Al2O3@BNNS/RTV-2SR柔性導熱絕緣復合膜。結果表明，Al2O3@BNNS異質結構導熱填料對RTV-2SR導熱復合膜的導熱性能具有協同提升效應。當Al2O3@BNNS用量為30 wt%（Al2O3:BNNS，1:1，wt:wt）時，Al2O3@BNNS/RTV-2SR導熱復合膜的面內λ（λ∥）和面間λ（λ⊥）分別達到2.86 W/mK和0.89 W/mK，為純RTV-2SR的λ∥（1.01 W/mK）和λ⊥（0.21 W/mK）的2.8倍和4.2倍，且優于相同填料用量下的BNNS/RTV-2SR（單一BNNS，λ∥=2.46 W/mK，λ⊥=0.76 W/mK）、Al2O3/RTV-2SR（單一Al2O3，λ∥=1.62 W/mK，λ⊥=0.49 W/mK）和Al2O3/BNNS/RTV-2SR（Al2O3/BNNS簡單共混，1:1，wt:wt，λ∥=2.04 W/mK，λ⊥=0.62 W/mK）導熱復合膜。并且，本文制備的Al2O3@BNNS/RTV-2SR導熱復合膜兼具良好的力學性能、絕緣性能和耐熱性能，當Al2O3@BNNS用量為30 wt%時，其拉伸強度、斷裂伸長率、硬度、介電常數（e）、介電損耗（tand ）、體積電阻率（ρv）、玻璃化轉變溫度（Tg）和耐熱指數（THRI）分別達到0.84 MPa、175%、27 HA、3.89、0.0088、5.76×1010 Ω·cm、-44.1oC和185.3oC。本工作為異質結構導熱填料及柔性導熱絕緣復合膜的制備研究提供了一種新的思路，在5G電子電氣設備領域具有潛在的應用。