|
Silicone rubber based knowledge
I. overview
Silicone rubber rubber Silicone is a kind of molecular chain and polymer with inorganic and organic properties. Its molecular chain is composed of silicon atoms and oxygen atoms.
Alternating composition (-SI-O-SI-), the silicon oxygen bond energy than the general rubber carbon carbon bond bond can be much greater, which is the silicone rubber with high thermal stability
One of the main reasons. Its molecular side chain is connected with the silicon atoms of the hydrocarbon or replaced by the hydrocarbon organic groups, early, this group is methyl, later,
In order to improve the rubber vulcanization activity and other modified, and gradually developed to introduce very small amounts of unsaturated vinyl (generally not more than 0.5MOL% side chain on the
Or other organic substituents. The low molecular structure of this kind of low unsaturated silicon rubber has excellent heat resistance and aging resistance, UV and ozone.
Function is very stable.
Two, classification and development
1. According to the mechanism of sulfide, silicone rubber can be divided into three categories.
A. organic peroxide initiated free radical crosslinking (thermal type)
B. condensation reaction type (room temperature vulcanization type)
C. addition reaction type
2 in recent years, the domestic and international research and development of several kinds of typical silicone rubber
A. silicon nitrogen rubber has a very high thermal stability, and the is not decomposed at 430~480, and some are resistant to high temperature, which can be used at 350.
Ten hours.
B. poly two methyl silicone / poly carbon block copolymer
With high transparency, heat resistance, UV resistance and other properties
C. poly two methyl silicone and polyurethane block copolymer
Special mechanical strength of surface characteristics with good anticoagulant properties.
3, the tensile strength and tear strength of silicone rubber are low, the poor and the poor, and the poor performance of the processing technology of complex products is in recent years.
A lot of modification work. Several of the following.
The improvement of the molecular structure of silicone rubber, the copolymerization of silicone with other monomers or polymers, in order to obtain new properties, such as organic silicon and poly
Between the silicate ester block copolymer, as to the choice of the gas film, silicone and EP rubber blends (said the shin Etsu SEP), their characteristics between silicon EPDM rubber
.
II improves performance: with rubber performance improvement and development of technology with the developed high strength, high tear strength, low compression deformation properties and good
High temperature resistance, low temperature resistance, flame retardant, heat conduction, thermal absorption of silicon rubber and other special purpose of the new varieties.
Improving the processing performance, was developed without a sulfide silicon rubber, silicone rubber particles (also known as the powder rubber) and based on vinyl containing polysiloxane and oxygen
The silicone rubber liquid injection molding system was developed by the reaction between the silicone.
Three, performance
(a) high temperature resistance, excellent
Silicone rubber has the widest operating temperature range (-100 ~ 350) but it must be pointed out that the high temperature and high temperature sealing performance of silicone rubber is very poor.
Isolated air, especially when there is water, will cause a rapid decline in the strength of silicone rubber, and even cracking down into low molecular weight. This shortcoming can be passed
Adding special heat stabilizer - Cerium compounds.
(two) excellent ozone resistance, ageing resistance, weathering aging
Silicone rubber vulcanized rubber in the free state in the outdoor exposure after a few years, no significant change in performance.
(three) excellent electrical insulation properties
After burning, the silicon dioxide is still in the insulator, which has good resistance to corona resistance and arc resistance.
(four) special surface properties and physiological inertia
The surface energy of silicone rubber is lower than that of most organic materials. Therefore, it has a low moisture absorption, which is immersed in water for a long time, and the water absorption is only 1%.
Drop, good antifungal properties, in addition, it does not stick to the material, can be isolated. Silicone rubber, tasteless, non-toxic, no adverse effects on the human body.
(five) high air permeability
At room temperature, the transmittance of N2, O2 and air is 30 ~ 40 times higher than that of NR, and it has the choice of gas permeability, which is 1 times of N2.
(six) special silicone rubber oil resistance, radiation resistance, flame resistance.
(1) oil resistance of aliphatic, aromatic and chlorinated hydrocarbon solvents, petroleum based fuel oil, lubricating oil, hydraulic oil, under normal temperature and high temperature stability
Qualitative is very good, to ethanol, acetone, etc. have very good resistance to.
(2) flame retardant   use of flame retardant can be made.
(3) radiation resistance
Four, vulcanized silicone rubber
The molecular weight of 40~60 is 10 thousand of silicone rubber, and peroxide as the curing agent.
This paper is from Shenzhen,, id=600?
This love or feel this to help you, please share it with your friends ^_^
|
Online Service 