Free radical polymerization overall extent

To approach truly living conditions in free radical polymerization, the extent of the termination reactions has to be reduced as much as possible. The natural way to establish such conditions is the reduction of the concentration of active chains, which, in turn, results in the decrease of polymer productivity. To contrast such decrease, the segregation of the radical chains, which is present in heterogeneous processes such as emulsion polymerization, can be exploited. This allows reducing terminations while preserving the overall concentration of radical chains. However, the appUcation of RAFT mediated polymerizations to emulsion systems has also been rather problematic, mainly with respect to the transport of RAFT agent through the aqueous phase. Attempts to carry out RAFT polymerizations in ab-initio emulsion processes... 

The melting temperature, extent of crystallinity, modulus, and mechanical behavior depend on the method of manufacture and the addition of comonomers, as well as overall molecular weight. Polyethylene is manufactured by several major processes (1,2) The high-pressure, free-radical polymerization, the Ziegler process, and the newer metallocene-catalyzed polymers and the metallocene-Ziegler processes see Table 14.2. 

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