Ozone aging testing exposes specimens to air containing a constant ozone concentration in a closed, light-free test chamber at a constant temperature. The specimens are inspected at predetermined intervals, and their ozone aging resistance is evaluated based on the degree of cracking or other performance changes on the specimen surface.
Ozone aging tests are applicable to vulcanized rubber, thermoplastic rubber, cable insulation and sheathing, hoses, seals, plastics, electronic components and more.
Ozone aging test methods
There are two main ozone aging test methods: static strain testing and dynamic strain testing:
Static strain test parameters
Ozone concentration, temperature, relative humidity, maximum elongation
Dynamic strain test parameters
Ozone concentration, test temperature, maximum elongation, dynamic strain frequency, gas flow rate or flow
(1) Ozone concentration
The optional ozone concentrations (volume fractions of 10-8) for the ozone aging test of specimens are: (25 ± 5)*10 - 8, (50 ± 5)*10 - 8, (100 ± 10)*10 - 8, (200 ± 20)*10 - 8. If required, other higher concentrations may also be used. Unless otherwise specified, the test is generally conducted at an ozone concentration of (50 ± 5)*10-8. The ozone concentration used in the test should be selected according to the ozone cracking resistance of the rubber and the service conditions. If the rubber is known to be used in a low ozone concentration environment and only a low ozone concentration test is required, testing at a concentration of (25 ± 5)*10 - 8 is recommended; for testing polymers resistant to high ozone concentrations, testing at (100 ± 10)*10-8 or (200 ± 20)*10-8 is recommended.
Note: The ozone concentration can be expressed as the ozone partial pressure in MPa; an ozone concentration of 1*10-8 is equivalent to an ozone partial pressure of 1.01 MPa.
(2) Test temperature
The most suitable test temperature is 40±2℃. Other temperatures may also be selected according to the service environment, such as 30±2℃ or 23±2℃, but the results obtained using these temperatures differ from those obtained at 40±2℃.
Note: If temperatures that vary significantly may be encountered in application, it is recommended to use two or more temperatures within the application range.
(3) Relative humidity
At the test temperature, the relative humidity of the ozonized air generally should not exceed 65%. Excessive humidity will affect the test results; for products used in humid climates, the test should be conducted at a relative humidity of 80% to 90%.
(4) Elongation
One or more of the following elongations are usually selected for testing: 5% ± 1%, 10% ± 1%, 15% ± 2%, 20% ± 2%, 30% ± 2%, 40% ± 2%, 50% ± 2%, 60% ± 2%, 80% ± 2%.
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