Influence of Concentration of Ozone upon Cracking of Vulcanized Rubber

Abstract

1. The character of the dependence of the time to first cracking (τ0), of the rate of crack growth in the steady-rate portion (v) and of the time to rupture (τ1) upon deformation does not alter on altering the ozone concentration from 0.15 to 0.0002%. 2. The value of the critical deformation does not alter with alteration in the ozone concentration. 3. The process of destruction of deformed rubber in ozone proceeds kinetically, i.e., it does not depend upon the rate of supply of ozone to the surface of the specimen. The character of the dependences τ0 and τ1 and of the rate of crack growth (vgrowth) upon the ozone concentration is determined by equations of the type of the Freundlich adsorption equation. 4. In the determination of the relative resistance of various vulcanized rubbers to ozone cracking it is desirable to select as an index the value of the ozone concentration at which we get a time to rupture equal for all vulcanized rubbers. 5. The relative resistance of the different vulcanized rubbers to ozone cracking (in assessment by the time to rupture) depends upon the ozone concentration at which it is determined. It is advisable to determine the resistance to cracking at the critical deformation of the vulcanized rubber. 6. The order of resistance to ozone of specimens of one rubber deformed by differing amounts does not depend upon their concentration in the range of concentrations under investigation and usually employed. However, if in the range of high concentrations of ozone the times to rupture of the specimens have values close to each other, then in the range of low concentrations of ozone these values may differ markedly.

A Review of Polymer Interfaces in Tyre Technology

“…264 Ozone cracking occurs at much lower stresses than those required for mechanical oxidative growth, the cracking increasing with ozone concentration. [282][283][284] The effect of concentration is large at deformations below the fatigue limit. 262,265 The presence of low levels of ozone (0.5 ppm) in a laboratory test also increased the crack growth rate by an amount roughly equal to the amount of oxidation (by air) alone.234*267…”