Physical and chemical properties test of nitrile rubber O-ring

The physical and chemical performance tests of Nitrile Butadiene Rubber O-rings (NBR O-rings) are essential to ensure their quality and reliability. These tests not only help manufacturers and users understand the performance of the material, but also provide a scientific basis for product design and application optimization. The following are the main physical and chemical performance tests of NBR O-rings and their standard methods:

1. Mechanical performance test

Tensile performance:

Test standard: ISO 37, ASTM D412

Test method: Stretch the sample to break, and record the breaking strength and elongation at break.

Purpose: Evaluate the tensile strength, elongation at break, elastic modulus, etc. of NBR to determine its mechanical durability.

Tear performance:

Test standard: ISO 34-1, ASTM D624

Test method: Apply tearing force to the sample and measure the tearing strength.

Purpose: Evaluate the tearing resistance of NBR materials, which is suitable for application environments subject to shear force.

Hardness test:

Test standard: ISO 868, ASTM D2240

Test method: Use Shore A hardness tester to measure the hardness of the sample.

Purpose: Provide quantitative data of material hardness to match different application requirements.

2. Oil resistance test

Volume change rate:

Test standard: ISO 1817, ASTM D471

Test method: Soak the sample in a specific medium (such as oil, fuel, chemical reagent) and measure its volume change within a specified time.

Purpose: Evaluate the expansion or contraction of nitrile rubber in different chemical media to determine its oil resistance and chemical stability.

Mass change rate:

Test method: Similar to the volume change test, but the parameter measured is the mass change of the sample.

Purpose: Provide additional chemical resistance performance data to help comprehensively evaluate the changes of materials in oil-soluble environments.

3. Thermal aging performance test

Hot air aging:

Test standard: ISO 188, ASTM D573

Test method: Expose the sample to hot air at a set temperature for a certain period of time, and measure the performance changes before and after aging.

Purpose: Evaluate the aging performance of nitrile rubber in a high temperature environment and predict its long-term service life.

Thermogravimetric analysis (TGA):

Test method: Measure the mass change of the sample at a specific heating rate.

Purpose: Evaluate its thermal stability and possible decomposition temperature by analyzing the mass change curve of the sample.

4. Chemical stability test

Chemical medium immersion test:

Test standard: ASTM G21, ISO 1817

Test method: Immerse the sample in a variety of chemical media (such as acid, alkali, solvent) and observe the changes in its appearance, mass and volume.

Purpose: Evaluate the chemical corrosion resistance of nitrile rubber in different chemical media.

Ozone aging test:

Test standard: ISO 1431-1, ASTM D1149

Test method: Expose the sample in an ozone environment and observe the formation and development of cracks.

Purpose: To evaluate the aging resistance of NBR in ozone environment, suitable for applications in high ozone or ultraviolet radiation environment.

5. Dynamic performance test

Rotating ring seal test (RSTM):

Test method: Simulate actual working conditions, install the NBR O-ring in the rotating ring seal test machine, and measure its sealing performance and wear.

Purpose: To evaluate the sealing effect and wear characteristics of the NBR O-ring under dynamic working conditions.

High-pressure reciprocating seal test (GP-CYCLE):

Test method: Under high pressure conditions, reciprocating motion is performed to evaluate the sealing performance and wear resistance of the NBR O-ring.

Purpose: To test the reliability of the NBR O-ring under high pressure and frequent motion conditions.

6. Microstructure analysis

Scanning electron microscope (SEM):

Test method: Observe the micromorphology of the aged sample.

Purpose: To study the changes in the microstructure of the NBR during aging.

Fourier transform infrared spectroscopy (FTIR):

Test method: Analyze the infrared absorption spectrum of the sample to identify the changes in chemical bonds produced during aging.

Purpose: To further understand the aging mechanism of nitrile rubber through changes in chemical structure.

Conclusion

By conducting comprehensive physical and chemical performance tests on nitrile rubber O-rings, we can systematically understand their performance under different working conditions and provide scientific support for material selection, product design and application optimization. These tests not only help improve the quality and reliability of nitrile rubber O-rings, but also promote the technological progress of related materials and processes.

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