1 Scope
This standard specifies procedures intended for use in estimating the resistance of vulcanized or thermoplastic rubbers to cracking when exposed, under static tensile strain, to air containing a definite concentration of ozone and at a definite temperature in circumstances that exclude the effects of direct light.
This standard is applicable to vulcanized or thermoplastic rubbers.
Note: Great caution is necessary in attempting to relate standard test results to service performance since the relative ozone resistance of different rubbers can vary markedly depending on the conditions, especially ozone concentration and temperature. In addition, tests are carried out on thin test pieces deformed in tension and the significance of attack for articles in service can be quite different owing to the effects of size and of the type and magnitude of the deformation. Explanatory notes on the nature of ozone cracking are given in Appendix A.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document(including any amendments) applies.
GB/T 528-2009 Rubber, Vulcanized or Thermoplastic — Determination of Tensile Stress-strain Properties (ISO 37:2005, IDT)
GB/T 2941-2006 Rubber — General Procedures for Preparing and Conditioning Test Pieces for Physical Test Methods (ISO 23529:2004, IDT)
GB/T 11206-2009
ISO 1431-3 Rubber, Vulcanized or Thermoplastic — Resistance to Ozone Cracking — Part 3: Reference and Alternative Methods for Determining the Ozone Concentration in Laboratory Test Chambers
3 Terms and Definitions
For the purpose of this document, the following terms and definitions apply.
3.1
Threshold strain
Highest tensile strain at which a rubber can be exposed at a given temperature to air containing a given concentration of ozone without ozone cracks developing on it after a given exposure period.
3.2
Limiting threshold strain
Tensile strain below which the time required for the development of ozone cracks increases very markedly and can become virtually infinite.
