稀土催化剂的性质——添加不同结构的化合物对丁二烯聚合的影响

探讨了一系列不同结构和极性的化合物对以稀土催化的丁二烯聚合的影响。这些添加剂中绝大多数降低了催化活性,并使聚合物的分子量上升,而只有烯丙基衍生物虽然降低了催化活性,却使聚合物的分子量下降。从稀土催化剂的活性中心寿命很长和其对普遍用于Ziegler-Natta催化体系的调聚剂的不敏感性看来,稀土催化体系具有一定的特点,其聚合机理有可能与一般过渡金属催化体系不尽相同。

THE NATURE OF THE RARE-EARTH CATALYTIC SYSTEM——THE EFFECT OF ADDITIVES ON THE POLYMERIZATION OF BUTADIENE

The effects of a series of eompooinds having varied structure and polarity on the polymerization of butadiene with the rare-earth catalytic system were studied. It was found that for most of these compounds the catalytic activity is lowered and the molecular weight of the polymers is increased, with the exception of allyl derivatives both the catalytic activity and the molecular weight are lowered. In view of its relative long lifetime and the insensitiveness towards modifiers usually used in Ziegler-Natta cataly-tic systems,the rare-earth catalytic system is assumed to have its special nature,lead-ing to somewhat different polymerization mechanism.