Test conditions for vulcanized rubber ozone aging test chamber
Ozone concentration: The ozone concentration used in the test should be selected according to the degree of aging resistance of the vulcanized rubber and the conditions of use. The available ozone concentration (unit: pphm) is 25 ± 5, 50 ± 5, 100 ± 10, 200 ± 20, 500 ± 50 or 1000 ± 100 or more (permissible deviation ± 10%). Generally, vulcanized rubber can be tested at 50 ± 5 pphm. For the more resistant aging rubber, it is better to use a higher ozone concentration for testing.
Temperature: The optimum test temperature should be 40 ± 2 °C. Other test temperatures (eg 30 ± 2 ° C or 23 ± 2 ° C) may be used depending on the temperature of the environment or equipment, but not higher than 60 ° C. The results obtained from tests at different temperatures cannot be compared to each other.
Relative humidity: The relative humidity of ozone-containing air should not exceed 60% unless otherwise specified.
Flow rate or flow rate: The flow rate of ozone-containing air in the ozone aging test chamber is not less than 8mm/s, and most preferably between 12 and 16mm/s (the value can be divided by the gas flow rate measured in the tank) The effective cross-sectional area perpendicular to the airflow is calculated, or the flow rate of the ozone-containing air, that is, the displacement per minute is preferably 3/4 of the volume of the tank.
Elongation: The static tensile condition of the sample can be selected from one or more of the following elongations (%): 5±1, 10±1, 15±2, 20±2, 30±2, 40±2, 50 ±2, 60±2, 80±2. If the test uses only one elongation, it should generally be 20%.
Treatment conditions: The environmental treatment before the test is in accordance with GB2941-82 "Standard temperature, humidity and time of rubber sample parking and test". The environmental treatment of the sample after stretching should be allowed to stand in an ozone-free dark room at a standard temperature (eg 23 ± 2 ° C) for 24 to 48 h. The constant temperature treatment of the test before the ozone test should be carried out in an ozone aging test chamber for 15 minutes.