Because sometimes the best defense is to get attacked first. 7PPD belongs to a family of chemicals called p-phenylenediamine antidegradants. They help protect rubber from oxygen, ozone, and the damage caused by repeated bending and stretching.
The strategy is surprisingly clever. Rubber contains molecular structures that ozone can attack. Left unprotected, microscopic damage can develop into cracks, especially when the material is repeatedly flexed. 7PPD acts like a molecular bodyguard.
Global Chemical Database