What are the applications of sealing adhesives in aerospace instruments (2)


What are the applications of sealing adhesives in aeros […]

What are the applications of sealing adhesives in aerospace instruments (2)

2. Polyurethane sealant

Polyurethane sealant is a kind of elastic sealing adhesive based on polyurethane rubber. Polyurethane rubber is a special kind of rubber, it is actually a kind of polymer compound between general rubber and plastic.

The biggest feature of polyurethane elastic sealant is that the surface hardness is high, it is elastic, and it has excellent cold resistance and oil resistance. Its bond strength at low temperature is even higher than that at room temperature. If the raw material composition and ratio are changed, it can obtain excellent elastomers with a Shore hardness of 20 to 80, an elastic modulus of 50 to 6000 kg/cm, and a tensile strength of 50 to 80 kg/cm. With such excellent properties, there is currently no more suitable elastomer to replace it.

3. Silicone rubber elastic sealant

The base of the silicone rubber type elastic sealant is a high molecular weight linear polysiloxane. Its molecular primary bond consists of alternating silicon and oxygen atoms.
Since the bond energy of the silicon-oxygen bond is much higher than that of the carbon-carbon bond of other polymer compound molecules, it has high heat resistance and cold resistance, and can be maintained in the temperature range of -65 ℃ to 250 ℃. good elasticity. In addition, it does not contain double bonds on its molecular side bonds, so it has excellent aging resistance and is very stable to ultraviolet rays and ozone. After ten years of atmospheric aging and three years of artificial accelerated aging, the aging phenomenon such as cracking, brittleness and peeling will not occur.

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