This part of ISO 1431 specifies a method for the determination of 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.
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 according to 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 may be quite different owing to the effects of size and the type and magnitude of deformation. Explanatory notes on the nature of
ozone cracking are given in annex A.
Methods for determining resistance to ozone cracking under dynamic strain conditions and combined dynamic and static strain conditions are specified in ISO 1431-2. A reference
method for estimating the ozone concentration will form the subject of ISO 143-3.