Silicone sealant is a key material in construction and industry due to its durability and elasticity. Its performance is primarily determined by two core properties: Tensile Strength and Elongation.
1. Core Performance Metrics
Tensile Strength (MPa): The sealant's resistance to breaking under tension, indicating its strength and rigidity.
Typical Values: Standard products: ~0.5 - 1.0 MPa; High-quality weatherproof sealants: ≥ 1.5 MPa; Structural sealants (highest requirement): ≥ 1.0 MPa, with premium products reaching ≥ 2.0 MPa.
Elongation (%): The extent the sealant can stretch before breaking, indicating its flexibility and elasticity.
Typical Values: Standard products: ~150% - 300%; High-quality weatherproof sealants: typically ≥ 400%, with some excellent products exceeding 800%; Structural sealants have a lower requirement but are generally ≥ 100%.
2. Synergistic Effect
These properties work together to ensure sealing performance, especially in dynamic joints.
Role of Elongation: Handles joint movement from thermal expansion, wind load, etc. High elongation allows the sealant to stretch and compress like a spring, absorbing movement without cracking.
Role of Strength: Ensures the sealant is not torn during stretching and can recover its shape after the stress is removed.
High-quality silicone sealants seek a balance of high strength and high elongation – being both tough and flexible.
3. Modulus & Selection Guide
Modulus: The force required to deform the sealant.
High Modulus: Rigid, high strength. Suitable for structural bonding with minimal movement.
Low Modulus: Flexible, high elongation. Ideal for weatherproofing dynamic joints.
| Application Scenario | Core Requirement | Performance Focus & Typical Value Reference |
|---|---|---|
| Weatherproof Sealing (Curtain walls, windows/doors) | Accommodate significant thermal movement | High Elongation (≥ 400%), Low Modulus Tensile Strength ≥ 1.0 MPa |
| Structural Bonding (Structural glazing, load-bearing) | Withstand permanent loads & wind pressure | High Tensile Strength (≥ 1.0 MPa, often higher), High Modulus Elongation ≥ 100% |
| General Purpose Sealing (Indoor, static joints) | Basic sealing & adhesion | Balanced Performance Tensile Strength ~0.8 MPa, Elongation ~200% |