The diolefins and alkenyl aromatics are very unstable components which can give gums by polymerization.In giving olefins and alky aromatics the hydrogenation improves the product quality.

二烃和烃是非常不稳定的组分，聚合产凝胶。对于给定烃和烷烃，氢改善产品质量。

Three Yuan second grade third rubbers (EPDM) is the ethylene, the propylene and the few non-conjugate diolefin copolymer.

三元乙丙橡胶（EPDM）是乙、丙和少量非共轭二烃的共聚物。