Molecular Weight Distribution of SPS with Heterogeneous Catalysts

4 Molecular Weight Distribution of SPS with Heterogeneous Catalysts 

With an assumption of single-site catalytic polymerization mechanism, the instantaneous number-average degree of polymerization is represented by the following equation  

In the two-site model, it is assumed that the catalytic sites have the same polymerization activity (propagation activity) but they differ in their chain transfer capabilities. The two-site model is the simplest of the multisite model and its main advantage is that the number of adjustable parameters is minimal. The weight chain length distribution function of the two-site model takes the following form  

Notice that for each site, the polymer chain length distribution 

Although some discrepancies in very low molecular weight regions and very high molecular weight regions are present, the overall MWD profiles are adequately simulated by the two-site model. 

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