Research On Several Types Of Fillers To Improve The Thermal Conductivity Of Silicone Rubber

Silicone rubber has been widely used in recent years, because of its broad using temperature range, stable chemical properties, hypotoxicity, good thermal stability, etc. But silicone rubber material also has some disadvantages, such as low thermal conductivity, low electrical conductivity, and poor mechanical performance, all these defects have limited its further application. The method to modify silicone material is various, but the most widely used method is filling fillers in silicone rubber material. Based on the current research status, this paper focus on the following three aspects:1. Silicone rubber filled with thermally conductive alumina was fabricated as a class of thermal interface materials in this part. The thermal conductivity of the prepared filler/silicone rubber composite was measured as a function of filler loading. Effects of various filler with different phases and morphologies on the thermal conductivity of the composite were investigated by comparative method. When the filler loading is low, the composite filled with porous irregular-shaped a-alumina exhibits a higher thermal conductivity than that filled with γ-Al2O3 and spherical α-Al2O3. In order to achieve a high loading, spherical α-Al2O3 has the most pronounced effect due to its intrinsic high thermal conductivity, size and morphology for homogeneous dispersion in the polymer matrix, which is superior to irregular-shaped α-and γ-Al2O3. Our results demonstrated that the composite filled with spherical alumina by the mass concentration of 82% has six times thermal conductivity higher than pure silicone rubber. Thermogravimetric analysis studies exhibited that the thermal stability of the composite distinctly increases with filler loadings. The obtained data were compared with theoretical equations in the literatures that are used to predict the properties of two-phase mixtures.2. Silicone rubber filled with thermally conductive A1N was fabricated as a class of thermal interface materials in this part. The thermal conductivity of the prepared filler/silicone rubber composite was measured as a function of filler loading. The effects of A1N filler on the thermal conductivity of the composite is investigated by comparative method. The obtained data were compared with theoretical equations in the literatures that are used to predict the properties of two-phase mixtures.3.In this part, we used expanded graphite(EG) as substrate, and grow carbon nanotubes(CNTs) on the surface of expanded graphite, so as to realize the compositing of EG and CNTs in situ way. And we applied this kind of material as filler to fill liquid silicone rubber, and then studied the thermal conductivity of this silicone rubber composite.