ISO 1431-1-08:2012 pdf download.Rubber, vulcanized or thermoplastic -Resistance to ozone cracking -Part 1:Static and dynamic strain testing.
This part of ISO 1431 specifies procedures intended for use in estimating the resistance of vulcanized or
thermoplastic rubbers to cracking when exposed, under static or dynamic tensile strain, to air containing a definite concentration of ozone and at a definite temperature in circumstances that exclude the effects of direct light.
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 Annex A.
Reference and alternative methods for determining the ozone concentration are described in ISO 1431-3.
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.
ISO 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties
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
ISO 18899:2004, Rubber — Guide to the calibration of test equipment
ISO 23529, Rubber— General procedures for preparing and conditioning test pieces for physical test methods
3 Terms and definitions
For the purposes 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
NOTE It is important to distinguish threshold strain from limiting threshold strain defined in 3.2.
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
3.3
dynamic strain
strain (normally a tensile strain) varying sinusoidally with time at some selected repetition rate or frequency
NOTE The maximum strain and the repetition rate are used to describe the dynamic strain conditions.
4 Principle
Test pieces are exposed, under static tensile strain, under continuous dynamic strain, or under alternate periods of dynamic and static strain, in a closed chamber at a constant temperature, to an atmosphere containing a fixed concentration of ozone. The test pieces are examined periodically for cracking.
Three alternative evaluation procedures are described for selected values of ozone concentration and exposure temperature.ISO 1431-1-08 pdf download.