Silicone rubber molecule's main chain is composed of alternately arranged silicon and oxygen atoms, with each silicon atom connected with two organic groups. There are many classifications of silicone rubber, including solid silicone rubber and liquid silicone rubber (by pre-curing form), room temperature and high temperature silicone rubber (by vulcanization temperature), methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, fluorine silicon rubber, nitrile silicone rubber, etc. (by monomers used); general-purpose silicone rubber, ultra-low temperature resistant silicone rubber, ultra-high temperature resistant silicone rubber, high strength silicone rubber, oil resistant silicone rubber, medical silicone rubber etc. (by performance and usage).
Silicon rubber is an ageing-resistant, high and low temperature resistant and electricity-insulated as well as moisture, corrosion and pollution resistant material that plays an irreplaceable role in aviation, aerospace applications, national defense, machinery manufacturing, architectural decoration, biomedicine and other fields.
Silicone rubber was first synthesized in the United States by using ferric chloride as the catalyst and products made of this material were first introduced in 1945. However, the molecular chain of silicon rubber is soft, the interaction force is weak (less than 0.4MPa), so silicon rubber needs to be reinforced before actual usage. In 1948 when fumed silica (also known as pyrogenic silica, colloidal silicon dioxide) with high specific surface area was developed and successfully used in reinforcing silicon rubber, silicone rubber products finally could be used in practical applications and the introduction of said fumed silica laid the foundation for the development of modern silicone rubber production technologies. As of now, countries that are capable of producing silicone rubber from the synthesis of dimethyldichlorosilane include the United States, Russia, Germany, Japan, South Korea, and China.
Compared to common inorganic powder fillers (calcium carbonate, precipitated silica, etc.), adding fumed silica can increase the strength of silicone rubber by up to 40 times and the (yield point) modulus by about 10 times, and significantly improve its elongation and creep performance.
As an extremely re-fined amorphous inorganic nanomaterial that is obtained through the hydrolytic condensation of halogenated silane in high temperature oxyhydrogen flame, fumed silica (SiO2) boasts mall particle size, large specific surface area, high surface activity and good reinforcement, thickening, thixotropy, anti-settling, anti-sagging, dispersion properties.
Research shows that the surface silanol groups (Si-OH) of fumed silica react physically or chemically with silicone rubber macromolecule, then generates a silicon rubber molecular adsorption layer on the surface of silica, then a three-dimensional network structure is formed. This structure effectively limits the deformation of the silicone rubber molecular chain, thereby achieving the reinforcing effect.
Produced by HUBEI HUIFU NANOMATERIAL CO.,LTD. （former company name : Yichang Huifu Silicon Material Co., Ltd.), HL-200 and other hydrophilic fumed silica products which boasts high transparency and excellent reinforcing, thickening, thixotropic, anti-caking, anti-settling properties, have been widely used in silicone rubber production and other fields.