Newer Aspects of Active Centre Determination in Ziegler-Natta Polymerization using 14CO Radio-Tagging

The determination of the number of active centres in Ziegler Natta polymerization continues to be of increasing interest to researchers in this field of study. Since the pioneering work of Natta (1,2) well in excess of one hundred papers containing values for active centre concentrations have appeared in the scientific literature. Many of these papers have been concerned directly with the development and applications of appropriate methods for active centre determination to both first and subsequent generations of Ziegler-Natta catalysts. Indeed recent developments of high activity catalyst systems have done much to focus interest on this area of discovery since a knowledge of the number of actual propagating centres is a prerequisite for the determination of values of the rate constant of chain propagation. A knowledge of these quantities is essential in any informed programme for catalyst characterization and development.