Ziegler-Natta catalysts first generation

The intensity of the H3C- CH2 signal was attenuated irreversibly above 50 K and decreased below the detection Umit above 80 K. This observation was explained by assuming that the ethyl radicals diffuse and recombine at these temperatures, as has been observed for other surface radicals such as CHs and NO2. These results have demonstrated for the first time how free radicals are indeed generated on the surface of an active model Ziegler-Natta catalyst. 

TiCl3 catalysts for 1-butene polymerization have relatively low activity.883 The old Shell process made use of a first-generation Ziegler-Natta catalyst, and required de-ashing of the final polymer. The new Basell process makes use of a much improved high yield MgCl2-supported Ti-based ZN catalyst and a two-reactor setup. Improved... 

Table I. Selected First-Generation Ziegler-Natta Catalysts...

The polymerization of 1,3-dienes (e.g., 1,3-butadiene and isoprene) with Ziegler-Natta catalysts began in 1954, soon after the first results obtained in a-olefin polymerization since then many transition metal and lanthanide catalysts have been examined and several stereoregular diene polymers have been obtained [30, 31], 1,3-Dienes can generate several types of polymers having different stmctures trans-1,4 cis-1,4 1,2 and, in the case of asymmetric monomers (e.g., isoprene), 3,4. Stereoregular 1,2- or 3,4-polydienes may also exhibit iso- or syndiotacticity. (Figure 11.1). 

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