Preparation Of Silica Nanotubes And Study On Functional Silicone Rubber Composites

Silicone rubbe(rSR) is one of the most widely used high-performance materials in modern high-tech, aero-space and other fields, because of its flexibility of organic polymer and its inherent silicone advantages, including excellent thermal stability and climate resistance, but only when reinforced with relatively large amounts of filler. Improvements in mechanical properties are most important, but many alternative fillers such as layered fillers and porous fillers also readily provide special performance. One-dimensional nanomaterial silica nanotubes (SNTs) can also become the novel filler, since their inherent characteristics involve the hollow core structures, ultralarge specific surface areas.SNTs were synthesized through template-directed sol-gel method. The formation mechanism of SNTs and the influence of synthesis conditions on the formation of the SNTs were studied. Two types of modifiers such as vinyl triethoxysilane (A151) and hexamethyldisilazane (HMDS) were used to treat SNTs, and then the SNTs/SR nanocomposites were prepared by various preparation methods. The effects of types of modifiers, preparation methods and nano-fillers on mechanical property, electrical insulation, dielectric property and the other properties of SR were investigated.The results indicated that the morphology and purity of SNTs varied to a certain extent depending on the reaction conditions such as ammonia addition speed and the time allowed to stand after ammonia addition. The width and its distribution of tubes increased with increasing time allowed to stand after ammonia addition, but the yield of tubes decreased. When ammonia was added in one time, tubes with small width, narrow width distribution and high purity were obtained.For the SNTs/SR composites, SNTs treated by HMDS displayed favorable dispersion, which increased the tear strength and decrease the dielectric loss. When nanocomposites were prepared by solution method,the tensile strength and tear strength increased, but dielectric loss decreased. The tensile strength, tear strength, shore A hardness, volume resistivity were all increased with the increasing of SNTs content, but swelling index and compression set were all decreased. Due to the air with low dielectric constant was incorporated into the SR matrix, delectric constant and dielectric loss decreased by introduction of SNTs in proper amounts into SR matrix.