改性纳米BN/甲基乙烯基硅橡胶导热复合材料的制备

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

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(m·K)^-1,约为纯MVSR的(λ=0.18W(m·K)^-1)5倍,也高于相同nBN用量的nBN/MVSR导热复合材料的λ(0.77W(m·K)^-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)。

The silane coupling agent KH550and 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 increaseλand decreaseεand tanδof the nBN/MVSR composites.The maximumλvalue of the POSS-g-nBN/MVSR composites improves to 0.92W/(m·K)with 30vol%POSS-g-nBN,which is about 5times of the pure MVSR matrix(0.18W(m·K)^-1)and also higher than that of nBN/MVSR composites with 30vol%nBN(0.77W(m·K)^-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 correspondingεand tanδof the POSS-g-nBN/MVSR composites are 3.39and 0.0049,respectively,slightly lower than that of nBN/MVSR composites with 30vol%nBN(εof 3.43and tanδof 0.0057).