The ozone ageing of natural rubber leads to fast cracks and a reduced lifetime of components in industrial applications. To replace fatal components, it is necessary to predict the degradation status, whereby the ultimate objective is to generate a database to model the evolution of the material’s ozone-ageing behaviour. To this end, thermal, chemical, and mechanical experiments are conducted to gain more insight into the process of ozone ageing and quantify the resulting changes. An accelerated ageing process is developed to consider various influencing parameters such as the ozone concentration, ageing time, and temperature. The resulting changes are evaluated, based on their usefulness to describe the ageing process. Apart from changes in the thermal and chemical characteristics of the surface, the cracking for ageing under strain is the predominant ageing characteristic. An evolution equation is derived for the development of crack depth in the cross-section. A similar evolution is present for natural rubber compounds with and without antiozonants, except if wax is part of the compound as this leads to different crack growth rates. The findings indicate a deceleration but no stagnation of crack growth and enable a relation of accelerated ageing time under increased ozone concentration to realistic ozone loading for long periods.    «

The ozone ageing of natural rubber leads to fast cracks and a reduced lifetime of components in industrial applications. To replace fatal components, it is necessary to predict the degradation status, whereby the ultimate objective is to generate a database to model the evolution of the material’s ozone-ageing behaviour. To this end, thermal, chemical, and mechanical experiments are conducted to gain more insight into the process of ozone ageing and quantify the resulting changes. An accelerated...    »