How to improve the gasoline/fuel resistance of FKM rubber?
Improving the gasoline resistance of FKM (fluoroelastomer) rubber can be achieved by adjust the material formula in following aspects.
1. Optimize Polymer Composition
High Fluorine Content: Select FKM grades with a higher fluorine content. FKM elastomers typically contain between 65% and 71% fluorine by weight. Higher fluorine content generally improves chemical resistance, including resistance to gasoline and other hydrocarbons.
- Low Fluorine Content Grades (65-67%): Suitable for general chemical resistance.
- Medium Fluorine Content Grades (67-69%): Provide enhanced resistance to a broader range of chemicals, including gasoline.
- High Fluorine Content Grades (69-71%): Offer the best resistance to aggressive chemicals and fuels, including various types of gasoline.
2. Compounding and Formulation
- Filler Selection: Use high-quality fillers such as carbon black and silica that enhance the rubber’s mechanical properties without compromising its chemical resistance.
- Plasticizers and Processing Aids: Choose compatible plasticizers and processing aids that do not leach out or degrade in the presence of gasoline.
- Antioxidants and Antiozonants: Incorporate specific antioxidants and antiozonants to protect the rubber from oxidative degradation, which can be exacerbated by exposure to gasoline.
3. Crosslink Density
- Increase Crosslink Density: Adjust the curing process to increase the crosslink density, enhancing the rubber’s overall chemical resistance. This can be achieved by optimizing the type and amount of crosslinking agents used.
4. Polymer Blends
- Blending with Other Polymers: Blend FKM with other compatible polymers that offer complementary properties, such as improving low-temperature FKM flexibility while maintaining gasoline resistance.
How to validate gasoline/fuel resistance of rubber？
Summary of Tests for Gasoline Resistance of FKM Rubber (immersion test in gasoline 96℃ x 168h):
| Test | Purpose | Standard | Key Steps | Measurement | Test Criteriac (For Reference) |
|---|---|---|---|---|---|
| Volume Change Test | Measure swelling properties | ASTM D471 | Initial volume measurement, immersion, final volume measurement | Volume change percentage | Volume change ≤ 10% |
| Weight Change Test | Measure absorption/degradation | ASTM D1817 | Initial mass measurement, immersion, final mass measurement | Mass change percentage | Weight change ≤ 5% |
| Hardness Change Test | Measure physical property changes | ASTM D7619 | Initial hardness measurement, immersion, final hardness measurement | Hardness change (Shore A) | Hardness change ≤ 5 Shore A units |
| Tensile Strength and Elongation Test | Measure mechanical performance changes | ASTM D53504 | Initial tensile test, immersion, final tensile test | Changes in tensile strength and elongation | Tensile strength change ≤ 20%, Elongation change ≤ 20% |
By following these standardized testing methods and criteria, we can comprehensively evaluate the gasoline resistance of rubber material, ensuring it meets the required performance standards for specific applications.
