The Ziegler process is an industrial process for manufacturing high-density polyethylene using catalysts of titanium(IV) chloride (TiCl4) and aluminium alkyls (e.g. triethylaluminium, Al(C2H5)3). The process was introduced in 1953 by the German chemistKarl Ziegler. It allowed the manufacture of polyethylene at lower temperatures (about 60 degrees C) and pressures (about 1atm) than used in the original process. Moreover, the polyethylene produced had more straight-chain molecules, giving the product more rigidity and a higher melting point than the earlier low-density polyethylene. The reaction involves the formation of a titaniumalkyl in which the titanium can coordinate directly to the pi bond in ethene. In 1954 the process was developed further by the Italian chemist Giulio Natta, who extended the use of Ziegler' s catalysts (and similar catalysts) to other alkenes. In particular he showed how to produce stereospecific polymers of propene. Research Ziegler Process
 
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