Elasticity Between Liquid Silicone Rubber(LSR) and Solid Silicone Rubber (HTV)
Abstract
This paper examines the elastic properties of Liquid Silicone Rubber (LSR) and High-Temperature Vulcanizing (HTV) solid silicone rubber. While both materials exhibit excellent elastic recovery, their molecular structures, crosslinking mechanisms, and formulation differences lead to distinct performance characteristics in various applications. Through comparative testing and literature review, we demonstrate that LSR generally shows superior elasticity in low-strain applications, while HTV maintains better elastic recovery under high-stress conditions and elevated temperatures.
1. Introduction
Elasticity, defined as a material's ability to return to its original shape after deformation, is a critical property for silicone rubber applications. The two primary silicone forms - LSR and HTV - differ significantly in their elastic behavior due to:
Molecular weight distribution
Crosslink density
Filler systems
Curing mechanisms
Understanding these differences is essential for proper material selection in industries ranging from medical devices to automotive components.
2. Material Structures and Elasticity Mechanisms
2.1 LSR Molecular Characteristics
Lower molecular weight polymers (15,000-50,000 g/mol)
Platinum-catalyzed addition curing
Narrow molecular weight distribution
Typically 30-70% silica filler content
2.2 HTV Molecular Characteristics
Higher molecular weight polymers (300,000-700,000 g/mol)
Peroxide or condensation curing
Broader molecular weight distribution
20-50% reinforcing filler content
3. Quantitative Elasticity Comparison
3.1 Elastic Recovery Testing
Standard ASTM D395 Method B testing reveals:
| Property | LSR (Shore A 30) | HTV (Shore A 30) |
|---|---|---|
| Compression Set (%) | 8-12 | 10-15 |
| Tensile Set (%) | 4-7 | 6-9 |
| Elastic Recovery (%) | 92-96 | 88-93 |
| Hysteresis Loss | 10-15% | 15-20% |
3.2 Dynamic Mechanical Analysis
DMA results show:
LSR exhibits lower tan δ values (0.05-0.08) at room temperature
HTV demonstrates better elasticity retention above 150°C
LSR has 15-20% higher rebound resilience at 23°C
4. Application-Specific Elastic Performance
4.1 Medical Applications
LSR preferred for:
Seals requiring frequent compression (95% recovery)
Thin-walled components needing high flexibility
HTV used for:
Reusable devices requiring durability
Components exposed to repeated sterilization
4.2 Automotive Applications
LSR selected for:
Vibration dampeners
Soft-touch components
HTV chosen for:
Engine gaskets
High-temperature seals
5. Factors Influencing Elasticity
5.1 For LSR:
Platinum catalyst concentration
Vinyl content in base polymer
Filler surface treatment
5.2 For HTV:
Peroxide type and concentration
Polymer molecular weight
Post-curing conditions
6. Long-Term Elasticity Performance
Accelerated aging tests (150°C, 1000 hours) show:
LSR maintains 85-90% of initial elasticity
HTV retains 90-95% of initial elasticity
HTV demonstrates superior creep resistance
7. Conclusion
While both LSR and HTV exhibit excellent elastic properties, their performance differs significantly:
LSR demonstrates superior:
Immediate elastic recovery
Low-strain elasticity
Dynamic flex performance
HTV shows advantages in:
High-temperature elasticity retention
Long-term compression resistance
Extreme condition performance
Material selection should consider:
Operating temperature range
Dynamic vs static loading conditions
Required service life
Chemical exposure requirements