How to test the chemical resistance of Fluorosilicone Elastomer?
As a supplier of Fluorosilicone Elastomer, I understand the importance of ensuring the chemical resistance of our products. Chemical resistance is a crucial property for Fluorosilicone Elastomer, as it determines the material's suitability for various applications, especially those in harsh chemical environments. In this blog, I will share some methods on how to test the chemical resistance of Fluorosilicone Elastomer.
1. Understanding the Basics of Chemical Resistance
Before diving into the testing methods, it's essential to understand what chemical resistance means for Fluorosilicone Elastomer. Chemical resistance refers to the ability of the material to withstand the action of chemicals without significant degradation in its physical and mechanical properties. This includes resistance to swelling, dissolution, embrittlement, and loss of elasticity when exposed to different chemicals such as acids, bases, solvents, and fuels.
2. Sample Preparation
The first step in testing the chemical resistance of Fluorosilicone Elastomer is to prepare the samples properly. Samples should be cut from the same batch of material to ensure consistency. The size and shape of the samples can vary depending on the testing method and equipment used. Commonly, rectangular or circular samples with a specific thickness are prepared. For example, samples with a thickness of 2 - 3 mm and a surface area of about 10 - 20 square centimeters are often used.
It's important to clean the samples thoroughly before testing to remove any surface contaminants that could affect the test results. This can be done by gently wiping the samples with a clean, lint - free cloth and a suitable solvent that does not react with the Fluorosilicone Elastomer.
3. Immersion Testing
Immersion testing is one of the most common methods for evaluating the chemical resistance of Fluorosilicone Elastomer. In this method, the prepared samples are fully immersed in the test chemical for a specified period at a controlled temperature.
3.1 Selecting the Test Chemicals
The choice of test chemicals depends on the intended application of the Fluorosilicone Elastomer. For example, if the material is intended for use in the automotive industry, it may need to be tested against fuels, lubricants, and coolant fluids. If it's for use in the chemical processing industry, it may need to be tested against acids, bases, and organic solvents.
Some common test chemicals include:
- Acids: Such as hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and acetic acid (CH₃COOH).
- Bases: Like sodium hydroxide (NaOH) and potassium hydroxide (KOH).
- Solvents: For example, toluene, xylene, and ethanol.
- Fuels: Gasoline, diesel, and aviation fuel.
3.2 Immersion Conditions
The immersion time and temperature are critical factors in immersion testing. The immersion time can range from a few hours to several weeks or even months, depending on the chemical and the expected service conditions. The temperature is usually controlled to simulate the actual operating temperature. For example, if the material is expected to be used at room temperature (around 20 - 25°C), the immersion test can be conducted at this temperature. However, if it's for high - temperature applications, the test may be carried out at elevated temperatures, such as 70°C or 100°C.
3.3 Measuring the Changes
After the immersion period, the samples are removed from the test chemical, rinsed with a suitable solvent to remove any residual chemical, and then dried. Various properties of the samples are then measured and compared with the initial values.
- Volume and Mass Changes: The volume and mass of the samples are measured before and after immersion. An increase in volume or mass indicates swelling of the Fluorosilicone Elastomer, which can be a sign of chemical attack. The percentage change in volume or mass can be calculated using the following formulas:
- Percentage change in volume = ((V₂ - V₁) / V₁) × 100%
- Percentage change in mass = ((m₂ - m₁) / m₁) × 100%
where V₁ and m₁ are the initial volume and mass, and V₂ and m₂ are the volume and mass after immersion.
- Hardness Changes: The hardness of the samples is measured using a durometer. A change in hardness can indicate changes in the material's internal structure due to chemical exposure. For example, a decrease in hardness may suggest softening of the material, while an increase in hardness may indicate embrittlement.
- Tensile Properties: Tensile tests can be performed on the samples before and after immersion to measure changes in tensile strength, elongation at break, and modulus. A significant decrease in these properties indicates degradation of the material's mechanical performance.
4. Spray Testing
In some cases, the Fluorosilicone Elastomer may not be fully immersed in the chemical but rather exposed to chemical sprays. Spray testing can simulate real - world scenarios where the material is exposed to chemical mists or sprays.
4.1 Spray Equipment
A spray gun or a nebulizer can be used to generate a fine spray of the test chemical. The spray rate, droplet size, and spray pattern should be controlled to ensure consistent exposure of the samples.
4.2 Exposure Conditions
The samples are placed in a test chamber, and the chemical spray is directed at the samples for a specified period. The exposure time and the frequency of spraying can be adjusted according to the expected service conditions. Similar to immersion testing, the temperature and humidity in the test chamber should be controlled.
4.3 Evaluation
After the spray exposure, the samples are evaluated in a similar way to immersion - tested samples. Changes in appearance, such as discoloration, cracking, or blistering, are visually inspected. Physical and mechanical properties are also measured to assess the extent of chemical damage.
5. Other Testing Methods
5.1 Diffusion Testing
Diffusion testing is used to measure the rate at which a chemical diffuses through the Fluorosilicone Elastomer. This is important in applications where the material needs to act as a barrier to prevent the passage of chemicals. In diffusion testing, a sample is placed between two chambers, one containing the test chemical and the other a clean environment. The amount of chemical that diffuses through the sample over time is measured, usually by analyzing the concentration of the chemical in the clean chamber.
5.2 Stress - Chemical Resistance Testing
In real - world applications, the Fluorosilicone Elastomer may be subjected to both mechanical stress and chemical exposure simultaneously. Stress - chemical resistance testing combines mechanical stress, such as tension or compression, with chemical immersion or spray exposure. This type of testing can provide more realistic information about the material's performance under actual service conditions.
6. Our Fluorosilicone Elastomer Products and Chemical Resistance
At our company, we offer a wide range of Fluorosilicone Elastomer products, including Fluorosilicone Rubber for Hose, Transparent Fluorosilicone Rubber, and Fluorosilicone Rubber for Strap. All of our products undergo rigorous chemical resistance testing to ensure they meet the highest quality standards.
We understand that different applications require different levels of chemical resistance. That's why we work closely with our customers to understand their specific needs and provide customized solutions. Whether you need a Fluorosilicone Elastomer product with excellent resistance to fuels, solvents, or harsh chemicals, we can help.
7. Contact Us for Procurement and Technical Support
If you are interested in purchasing our Fluorosilicone Elastomer products or need more information about our chemical resistance testing methods, please feel free to contact us. Our team of experts is ready to assist you with any questions you may have regarding product selection, application, and technical specifications. We are committed to providing high - quality products and excellent customer service.
References
- ASTM D471 - Standard Test Method for Rubber Property - Effect of Liquids.
- ISO 1817:2015 - Rubber, vulcanized or thermoplastic - Determination of the effect of liquids.