Karl Ziegler was born in November 1898 near Kassel in Germany and died in August 1973 in Mülheim, West Germany. He shares with Natta the great distinction of the Nobel Prize for Chemistry awarded in 1963 for work which greatly enhanced the progress of plastics.
Ziegler received his doctorate in 1923 from the University of Marburg and held academic appointments in the Universities of Frankfurt am Main, Heidelberg and Halle. He became Director of the Kaiser Wilhelm Institute for Coal Research at Mülheim an der Ruhr (later the Max Planck Institute).
His earlier work involved the clarification of rubber synthesis reactions, cyclic carbon compounds used in perfumes and lithium in organic reactions.
Ziegler’s most important discovery was made in 1953 from his work on organo-aluminium compounds. With E. Holzkamp, a student, he found that substances made by mixing organo-metallic compounds with certain heavy metals permitted rapid polymerisation of ethylene at atmospheric pressure. This significant contribution established that very high molecular weight polyethylene could be produced with linear chain structure and give valuable production, property and application potential. The first full-scale, low pressure (high density) polyethylene plant was erected by Hoechst in 1955. The high pressure processes employed hitherto had produced lower density polymers with side branching.
The catalyst was derived from triethyl aluminium and titanium tetrachloride. Although many other catalyst systems and polymerisation methods were devised, this work formed the basis of later developments in the production of long chain polymers from olefins such as propylene and butadiene. (See Natta)
The modern polyethylene range of specifically structured polymers has provided products readily formed as films, fibres and mouldings applicable in many areas of modern life. Blow moulded bottles (eg for milk and household cleaners), injection moulded containers, toys and appliance components are daily reminders of Ziegler’s outstanding and original work.