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、丙和少量非轭。

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.

和基芳是非常不稳定组分，可合产生凝胶。对于给定和烷基芳，氢化可以改善产品质量。