| Aging processes, which are caused by oxygen or heat, change the properties of the vulcanizates. Rubbers generally are subject to such changes that occur in the course of time and can lead to partial or complete destruction. Possible consequences are depolymerization, fatigue, brittleness, cracks and even disintegration. The resistance of a rubber article to oxygen, ozone and other reactive substances is determined mainly by the elastomer on which the compound is based and by the chemicals that are added to retard the destructive processes. |
Unsaturated groups in the rubber molecule are the reason for the rubber's sensitivity to oxygen, which increases with temperature. If catalysts of oxidation (known as rubber poisons) are present, aging is rapid. The results are hardening and embrittlement, crazing effects and fatigue. Ozone or dynamic stress (fatigue) lead to cracking on the surface of the rubber article.
Antidegradants such as Vulkanox® are chemicals which protect the vulcanizates against damaging external influences. Depending on the chemical structure, they act against one or more of the aging processes mentioned. None of the antidegradants is universally effective, each has a definite spectrum of activity and characteristic effectiveness, and a definite propensity to discolor the goods if they are exposed to light. Staining antidegradants are generally more effective than non-staining ones.
- protection against oxidation, ozone, heat and rubber poisons
- protection against dynamic stress