Composition and Properties

Elastomers: They have high elasticity, allowing them to deform under pressure and then return to their original shape, which is crucial for adapting to the movement and deformation of the substrate. For example, natural rubber has good comprehensive performance, while silicone rubber has excellent high - temperature and low - temperature resistance.

Fluoropolymers: They have excellent chemical resistance, high - temperature resistance, and low friction coefficients. PTFE, for instance, can resist the corrosion of various strong acids, strong bases, and organic solvents, and it also has good self - lubricating properties.

Metals: Metals have high strength and good thermal conductivity. High - strength metals like stainless steel and copper - based alloys are suitable for high - stress and high - temperature - resistant environments, such as in some high - temperature pipelines.

Sealing Mechanisms

Chemical Bonding: Sealants form chemical bonds with the surfaces they are applied to, usually covalent bonds, by sharing electrons between the atoms of the sealant and the substrate. This ensures a strong adhesion, enabling the sealant to remain firmly attached to the surface even under the action of environmental stressors.

Physical Barrier: After application, sealants form a solid or flexible layer that blocks the movement of air, water, or other materials. For example, the waterproof layer formed by some sealants on building surfaces can effectively prevent rainwater from penetrating into the interior of the building.

Elastic Deformation: Many sealing materials can undergo elastic deformation to adapt to the movement and deformation of the substrate caused by factors such as thermal expansion and contraction. For example, O - ring seals can maintain a good sealing effect under different working conditions by deforming to fit the shape of the contact surface.

Factors Affecting Performance

Temperature: Each sealing material has a specific applicable temperature range. High temperatures may cause the material to soften, deform, or age rapidly, while low temperatures may make it brittle, reducing its elasticity and sealing performance.

Pressure: The pressure - bearing capacity of sealing materials varies. In high - pressure environments, materials with high strength and good sealing performance are required. Pressure fluctuations can also affect the sealing effect.

Chemical Compatibility: The sealing material needs to be chemically compatible with the medium it contacts. Otherwise, chemical reactions such as corrosion, swelling, or dissolution may occur, affecting the sealing performance.