Room temperature vulcanized silicone rubber products, rounding process performance index

by:Keyuan     2020-09-20
Room temperature vulcanized silicone rubber is a widely dosage of organic silicone industry of silicone rubber, RTV for short, as early as ten years ago at room temperature vulcanization silicone rubber in China has reached 300000 tons of demand, it is given priority to with the construction industry, used for glass glue, sealant, indoor decoration, doors and Windows sealed majority, as the industry currently USES gradual expansion and the innovation of the product research and development to its rapid development, and performance specifications of the products or not change, you have to know its material performance? ( 1) Table dry time means rtv-i silicone products exposed to atmospheric environment curing process, the fingers touch the appearance, viscosity of lost time. Under the condition of the general refers to the specifications, silicone rubber surface sealant extrusion air buy, appearance is not hands time distance. ( 2) Curing depth refers to the standard conditions, the silicone rubber surface sealant in the fixed mold, a certain period of time after the glue, silicone rubber surface sealant outside-in curing rubber thickness, such as: 2 ~ 3 mm / 24 h, 0. 6 mm/h, etc. ( 3) Extrusion ( Defined in accordance with the specification ASTMC1183) In accordance with ASTM C1183 specification request, under the condition of the specification, using Semco tubes and specific cement ( 3 in diameter. 2毫米) , under the condition of specific pressure, extrusion of weight per unit time is called out. ( 4) Instant sealing pressure refers to the silicone rubber surface sealant at a certain diameter sizing in the flange plate of plane, then immediately closed, control of thickness of the rubber has a reasonable, then in accordance with certain rate exert pressure, the biggest pressure for the instant sealing pressure to accept. ( 5) Oil refers to the silicon rubber curing properties in products surface sealant in the fixed mold, then die in the oil, records of silicone rubber surface sealant outside-in curing within a certain amount of time to represent the thickness of the silicone rubber surface sealant solidification features of oil. ( 6) Shear strength insist rate refers to the air buy time once sizing shear specimens under the specific conditions of high temperature, high humidity place after a certain amount of time, then stop fold glue, the specification is placed under the condition of 168 h stop curing and test its shear strength, and with the specification under the condition of direct bonding shear strength of cured 168 h test stop comparison, calculation strength rate. ( 7) Thermal stability is not the cure of the plane of silicone sealant in the environment of high temperature curing time, and then under the condition of specification can still curing, illustrate the silicone rubber surface sealant under the condition of the temperature is stable. Such as sealant temperature 100 ℃ or higher thermal stability refers to not curing sealant after 100 ℃ heating can still continue to curing. According to the phenyl content in silicone rubber ( Phenyl: the silicon atoms) Different, it can be divided into low phenyl, phenyl and high phenyl silicone rubber. Crystallization occurs when the rubber or close to the glass transition point or that the overlap of the two, both can lead to stiffness of rubber. Introducing the right amount of mass groups in the regularity of the polymer chain is damaged, can reduce the crystallization temperature of polymer, due to the introduction of mass groups at the same time change the force between the polymer molecules, so it can change the glass transition temperature. Low phenyl silicone rubber ( C6H5/Si=6~11%) Is due to the above reason has good low temperature resistance, and has nothing to do with phenyl monomer type used. The brittleness temperature for - vulcanized rubber 120 ℃, it is now the best rubber performance at low temperature. The advantages of low phenyl silicone rubber and vinyl silicone rubber, and the cost is not high, therefore has a tendency to replace the vinyl silicone rubber. When greatly improve the content of phenyl will make molecular chain rigidity increases, thus resulting in a loss of cold tolerance and flexibility, but ablation resistance and radiation resistance will be improved, phenyl content of C6H5 / Si = 20 ~ 34% of phenyl silicone rubber has the characteristics of ablation resistant, high phenyl silicone rubber ( C6H5/Si=35~50%) Excellent resistance to radiation performance.
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