The uses and functions of sealants can be analyzed from the following dimensions:
Core Uses
Construction Industry: Sealants are key materials for building sealing, commonly used in door and window installation, curtain wall splicing, pipe penetrations, and bathroom waterproofing. For example, silicone sealants, due to their strong weather resistance, are widely used for sealing joints in glass curtain walls; polyurethane sealants, due to their good elasticity, are suitable for filling concrete expansion joints.
Automotive Industry: In automobile manufacturing, sealants are used for sealing welded joints in the car body, bonding windshields, preventing leaks in the engine compartment, and providing corrosion protection for the chassis. For example, butyl rubber sealants, due to their high-temperature resistance, are often used for sealing engine compartments; while acrylic sealants, due to their fast curing, are suitable for assembly line operations.
Electronics and Electrical Appliances: In the electronics industry, sealants are mainly used for protecting circuit boards, fixing components, and sealing casings to prevent the intrusion of moisture, dust, or chemicals. For example, epoxy resin sealants are widely used for potting electronic components due to their strong insulation properties; silicone sealants, on the other hand, are suitable for sealing electronic equipment in high-temperature environments due to their good temperature resistance.
Aerospace: In the aerospace field, sealants must meet extreme environmental requirements, such as high temperature resistance, low temperature resistance, and radiation resistance. For example, fluorosilicone sealants, due to their excellent chemical resistance, are used for sealing aircraft fuel systems; polysulfide sealants, due to their good oil resistance, are suitable for sealing rocket propellant storage containers.
Mechanism of Action The mechanism of action of sealants is mainly based on their physical and chemical properties:
Filling Effect: Sealants can fill irregular gaps, forming a continuous sealing layer and preventing media penetration. For example, injecting polyurethane sealant into concrete cracks can effectively prevent rainwater infiltration.
Adhesive Effect: Sealants bond with the substrate through chemical bonds or physical adsorption, forming a strong adhesive interface. For example, the bonding strength between silicone sealant and glass can reach over 1 MPa, ensuring long-term sealing of curtain walls.
Elastic Recovery: Sealant should be able to elastically deform and return to its original shape after being subjected to stress, adapting to minor displacements of the substrate. For example, in building expansion joints, the elasticity of the sealant can absorb stress caused by thermal expansion and contraction, preventing cracking.
Weather Resistance: Sealant must resist environmental factors such as ultraviolet radiation, ozone, and temperature changes to maintain long-term performance stability. For example, silicone sealants maintain elasticity within a temperature range of -50℃ to 150℃, making them suitable for outdoor environments.