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Why is silicone rubber widely used？
Silicone rubber was first synthesized by the United States with ferric chloride as a catalyst. In 1945, silicone rubber products were introduced. In 1948, the silicone rubber reinforced by vapor phase white carbon black with high specific surface area was successfully developed, which made the performance of silicone rubber jump to the practical stage and laid the foundation of modern silicone rubber production technology.
Oct 16th,2023
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Silicone rubber refers to the main chain is alternately composed of silicon and oxygen atoms, silicon atoms are usually connected with two organic groups of rubber. Silicone rubber has good low temperature resistance and can generally work at -55 ° C. After the introduction of phenyl, it can reach -73℃. The heat resistance of silicone rubber is also very prominent, can work for a long time at 180 ° C, slightly higher than 200 ° C can also withstand a few weeks or longer is still elastic, instantaneous resistance to high temperatures above 300 ° C. The gas permeability of silicone rubber is good, and the oxygen permeability is the highest in the synthetic polymer. In addition, silicone rubber also has the outstanding characteristics of physiological inertia and does not cause coagulation, and the application field is relatively wide.
Silicone rubber thermal vulcanization type (high temperature vulcanized silica gel HTV), room temperature vulcanization type (RTV), of which room temperature vulcanization type is also polycondensation reaction type and addition reaction type. High temperature silicone rubber is mainly used in the manufacture of various silicone rubber products, while room temperature silicone rubber is mainly used as a bonding agent, potting material or mold. The amount of hot vulcanization type is the largest, and the hot vulcanization type is divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the amount and product grade are the most), methyl vinyl phenyl silicone rubber PVMQ(low temperature resistance, radiation resistance), and other rubber, fluorine silicone rubber.
(1) High temperature performance. The remarkable feature of silicone rubber is high temperature stability, although the strength of silicone rubber at room temperature is only half of natural rubber or some synthetic rubber, but in the high temperature environment above 200℃, silicone rubber can still maintain a certain flexibility, resilience and surface hardness, and mechanical properties have no significant change.
(2) Low temperature performance The glass change temperature of silicone rubber is generally -70~-50 ° C, and the special formula can reach -100 ° C, indicating that its low temperature performance is excellent. This is of great significance to the aviation and aerospace industry.
(3) Weather resistance Si-O-Si bonds in silicone rubber are very stable for oxygen, ozone and ultraviolet rays, and have excellent weather resistance without adding any additives.
(4) Electrical performance. Silicone rubber has excellent insulation properties, corona resistance and arc resistance are also very good.
(5) Physical and mechanical properties. The physical and mechanical properties of silicone rubber at room temperature are worse than that of general rubber, but at high temperatures of 150 ° C and low temperatures of -50 ° C, their physical and mechanical properties are better than that of general rubber.
(6) Oil and chemical reagent resistance. Ordinary silicone rubber has medium oil and solvent resistance.
(7) Gas permeability. At room temperature, the permeability of silicone rubber to air, nitrogen, oxygen, carbon dioxide and other gases is 30-50 times higher than that of natural rubber.
(8) Physiological inertia. Silicone rubber is non-toxic, tasteless, odorless, non-adherent to human tissue, has an anticoagulant effect, and has very little reactivity to body tissue. Especially suitable for use as medical materials.
