Batch Reactor, Terminal Double Bond Incorporation

Batch Reactor, Terminal Double Bond Incorporation [15] 

The problem of incorporation of chains with a terminal double bond (TDB) exists in polymerizations discussed above, such as radical polymerization of vinyl acetate and olefin polymerization with a constrained-geometry metallocene catalyst (CGC). Tobita [15] has developed an MC algorithm for this problem for the PVAc case. It is assumed that TDBs are created by transfer to monomer only, while recombination is absent, which results in a maximum of one TDB per chain. We largely follow Tobita s explanation, but differ in that we will assume that disproportionation is the termination mechanism, while transfer to solvent and to polymer are not yet being accounted for. Later we will address the real PVAc problem, which in fact has two branching mechanisms TDB propagation and transfer to polymer. 

we consider the possibility that this pp will be incorporated in a pp that grows later, at u 9 u y/. This depends, in the first place, on the probability that the first pp, grown aXx = 9, possesses a TDB  

In the second place, we have to know which fraction of the pps with a TDB grown at x = 9 will actually be incorporated as conversion increases, since together with 

Ptdb (6) this determines the probability of the randomly chosen pp at x = 0 becoming connected to a later pp. We should consider what happens to pps with a TDB after their creation at x = 6. A fraction of them is incorporated, but as the rate at which this happens depends on their concentration, this rate will decrease. In fact, the fractional decrease of these pps exactly follows the decrease in the fraction of TDBs of pps created at x = 6. The TDB mole-fraction, FrM( w), starts at Cm = km/kj, for all birth conversions, so also atx=9, while it decreases according to the balance describing the TDB consumption starting from 6  

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We will now discuss this method as applied on mostly branched radical polymerization systems involving transfer to polymer, terminal double bond incorporation, recombination termination, and random scission for both continuous and batch reactors. 

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