Monomer Conversion, Shortstop and Stabilization of Polymers

In the polymerization of BD by Ti-, Co- and Ni-based catalyst systems the polymerization has to be shortstopped at a specific monomer conversion in order to avoid the formation of gel. In contrast, polymerization catalysis by Nd catalysts does not need control of monomer conversion. As gel formation is particularly low with Nd catalysts full monomer conversion can be accomplished [427,428]. 

If the polymerization is shortstopped at a specific monomer conversion water, acids and alcohols are used. Water has to be properly mixed with the 

Organic solvents, residual monomer and dimers (Sect. 2.2.5) are usually removed by vapor stripping during which an aqueous slurry of Nd-BR is obtained. BR is isolated from the slurry by appropriate dewatering screws prior to drying by hot air [82]. The final process steps of Nd-BR-solutions are not unique to Nd-BR. Therefore, these aspects are not addressed in this review. 

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