Karl
Ziegler
discovered
high density
polyethylene
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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.
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