ABSTRACT
Age resisters added to raw synthetic polymers are usually called stabilizers. Some ingredients, such as carbon black, give significant age resistance but are not so classified because they are not added for that purpose. Age resisters are manufactured as liquids, viscous liquids, semisolids, powder, flakes and rods. Toxicity is a matter of importance in using any compounding material but is of more concern with age resisters and accelerators than with materials like sulfur and stearic acid. Material safety data sheets, available from most manufacturers, suggest correct handling procedures. Cost is always a consideration in rubber compounding and especially with age resisters. The age-resistant properties of compounds are largely tested by accelerated test such as hot air aging, measuring the rate of crack growth in strips subjected to constant flexing, and visual appearance of stretched samples in high ozone chambers.
