Ziegler-Natta catalyts

Zucchini, U. and Cecchin,G. Control of Molecular-Weight Distribution in Polyolefins Synthesized with Ziegler-Natta Catalytic Systems. Vol. 51, pp. 101 — 154. 

They are used as a component in the Ziegler-Natta catalytic system (AIR TiCh, etc.) in the polymerisation and copolymerisation of olefines. Besides, the high reactivity of these compounds makes them practical for many interesting syntheses (Fig. 87). 

Control of Molecular-Weight Distribution in Polyolefins Synthesized with Ziegler-Natta Catalytic Systems... 

However, in reality, polyolefins prepared by using Ziegler-Natta catalytic systems (which mainly are heterogeneous) show a polydispersity index which is generally... 

Table 6. Molecular weights and polydispersily of high density polyethylene obtained with some traditional and supported Ziegler-Natta catalytic systems ...

Yermakov et al. on the basis of both their own experimental data and the few one available from the literature, concluded that polyethylene, obtained with magnesium-based catalytic systems, though showing properties similar to that produced with traditional Ziegler-Natta catalytic systems (TiCl, -aluminum alkyls), presents generally a narrower MWD. 

With traditional heterogeneous Ziegler-Natta catalytic systems, polymers with broad MWD are formed just during the first instants of polymerization . At 25 °C with TiCl —AlIi-C HjIj, polyethylene MWD tends to broaden in the first thirty... 

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