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).