改性纳米BN/甲基乙烯基硅橡胶导热复合材料的制备

以甲基乙烯基硅橡胶（MVSR）为基体，硅烷偶联剂KH550与聚倍半硅氧烷（POSS）结合改性的纳米BN（POSS-g-nBN）为导热填料，经混炼-热压制备POSS-g-nBN/MVSR导热复合材料。结果表明，POSS-g-nBN/MVSR导热复合材料的导热系数（λ）、介电常数（ε）和介电损耗正切值（tanδ）均随nBN用量增加而增大。相同nBN用量下，表面功能化改性有助于进一步提高nBN/MVSR导热复合材料的λ，降低ε和tanδ。当POSS-g-nBN用量为30vol%时，POSS-g-nBN/MVSR导热复合材料的λ为0.92 W（mK）-1，约为纯MVSR的（λ=0.18 W（mK）-1）5倍，也高于相同nBN用量的nBN/MVSR导热复合材料的λ（0.77 W（mK）-1）。相比未改性nBN，POSS-g-nBN更易在MVSR基体内形成导热通路且和MVSR基体具有相对更低的界面热障。当POSS-g-nBN用量为30vol%时，POSS-g-nBN/MVSR导热复合材料的ε和tanδ分别为3.39和0.0049，略低于相同nBN用量的nBN/MVSR导热复合材料的ε（3.43）和tanδ（0.0057）。 

Preparation of functionalized nano BN/methyl vinyl silicone rubber thermally conductive composites

The silane coupling agent KH550 and polyhedral oligomeric silsesquioxane (POSS) functionalized nano BN (nBN)/methyl vinyl silicone rubber (POSS-g-nBN/MVSR) thermally conductive composites were fabricated via kneading followed by hot compression method. The thermally conductive coefficient (λ), dielectric constant (ε) and dielectric loss tangent (tanδ) values of the nBN/MVSR composites are all increased with increasing addition of nBN. For a given nBN loading, the surface functionalization of nBN can further increase λ and decrease ε and tanδ of the nBN/MVSR composites. The maximum λ value of the POSS-g-nBN/MVSR composites improves to 0.92 W/(mK) with 30vol% POSS-g-nBN, which is about 5 times of the pure MVSR matrix (0.18 W(mK)-1) and also higher than that of nBN/MVSR composites with 30vol% nBN (0.77 W(mK)-1). In comparison to that of pristine nBN fillers, POSS-g-nBN fillers are easier to form thermally conductive channels in MVSR matrix and possess relatively lower interfacial thermal resistance with MVSR matrix. The corresponding ε and tanδ of the POSS-g-nBN/MVSR composites are 3.39 and 0.0049, respectively, slightly lower than that of nBN/MVSR composites with 30vol% nBN (ε of 3.43 and tanδ of 0.0057).