The gas phase silica in the application of silicone rubber products

by:Keyuan     2020-09-28
Known food-grade silicone products have reached the threshold of the human body skin contact and daily-use products, but why it may not be the solution to a common silicone material and its don't of food-grade silicone material, or even more upscale medical grade silicone raw materials to distinguish, then today for the vast number of friends on what kind of food grade silica gel is a kind of material, with ordinary silica gel and the difference again! In the life of many common materials are silica gel products from ordinary silica gel material, chemical material from a set of white carbon black is also called as a method of silica gel, the difference between it and food grade silica gel is stretching white is more serious, combine ingredients in a variety of compounds can not meet the testing standards, such as the FDA and ROHS, LFGB testing certification, and won't have food grade silica gel in the tensile appear white phenomenon, the tensile strength can reach above 500%. The silica obtained silicon tetrachloride and air combustion, the fineness of more than 1000 mesh precipitation after production of sulfuric acid is added is the use of sodium silicate in the silica precipitation. Only 300 - fineness 400 mesh. So the gas phase method of silica gel compared with ordinary silica gel on the performance of price also clearly must be a little expensive. Food-grade silicone raw materials on silica is referred to as the gas phase by synthetic polymer particles compound material, good liquidity, high specific gravity, surface adsorption ability is stronger, because how many polymer compound gas phase silicon dioxide fusion and the purity of product is higher, dispersing performance is better, so just let it in the silicone products various performance advantage, with its excellent stability, reinforcing, thickening and thixotropic, and unique features in the field of the academic disciplines, having the effect that cannot replace. Gas phase silica on the mechanical behavior of HTV silicone rubber affect gas phase silica of HTV silicone rubber reinforcing affected by its size, comparative area and structural, is usually the smaller the particle size, the higher the specific surface area, the higher the structural reinforcing effect, the better, the higher the strength and hardness of vulcanized rubber. In addition, the amount of gas phase silica and its dispersion in the matrix is good or bad influence on the performance of vulcanized rubber is very big also, regarding the gas phase of silica on silicon rubber reinforcing mechanism and model is also very much, is approved by the explanation is that the gas phase free hydroxyl groups on the surface of the silica and silicon rubber molecules formed the physical or chemical combination, form of silicone rubber molecules adsorbed layer in the surface of silicon dioxide, a gas phase silica and silicon rubber molecules of three-dimensional network structure, thus effectively restrict silicone rubber deformation of molecular chain and its reinforcement effect. Analysis of the changes of the tear strength and tensile strength are similar, are as the gas phase silica reinforcing sex and increased, first increases with the increase of the amount of gas phase silica, after reaching peak decrease slightly. Gas phase silica on the properties of HTV silicone rubber products processing effects are typically structured degree ( 吗? Crepe) Said the Crepe mixing glue stored at room temperature is equal to the value (28 days of plasticity p28) And mixing immediately after the determination of the plasticity of value ( P0) , the difference between the plasticity of the value and the amount of gas phase silica, surface properties and structural. Structured cause is due to gas phase silica surface hydroxyl with the oxygen atoms to form hydrogen bond in the silicone rubber and silica surface adsorption of silicone rubber chain, cause the rubber with the extension of time, the liquid drops, rubber harden and affect the processing performance. So in use process need to add structure control agent or choose after surface treatment of gas phase silica, the structure control agent to join and gas phase surface treatment of silica, were controlled by structure or surface treating agent and silica surface hydroxy reaction, so as to reduce the surface hydroxyl number, which resulted in the reduction and the number of silicone rubber to form hydrogen bond, mixing time, mixing of rubber plasticity increases, it could reduce the structural effect, improve the processing performance and storage stability.
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