Nitroxide-mediated polymerization of styrene-divinylbenzene has been modeled using generating functions of length distributions, pseudo-kinetic propagations, and numerical fractionation with the crosslinking rate depending on generation. Cyclization reactions are tackled by balances of sequences, yielding fair predictions of the measured pendant double bond concentration. With reduction in crosslinking, agreement for the experiments at 90 8C between predicted and measured weight-average, molecular weight, and weight fraction of gel is observed. A much higher relative crosslinking reactivity is observed at 130 8C as compared to 90 8C, likely an effect of the chain mobility.

A kinetic model including the cyclic propagation (cyclization) is proposed for the nitroxidemediated radical copolymerization of styrene-divinylbenzene. The method involves a balance of sequences of units, which connect a radical center and a pendant double bond present in the same polymer chain. The rate constant for cyclization was considered a function of the sequence length. Good agreement between the model predictions and experimental data for solution and suspension controlled copolymerizations was found. The rate constant of cyclization for the smallest ring (3 monomeric units) was estimated to be 700 s À1 at 90 8C, and the activation energy was estimated to be 32 500 cal mol À1 .

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A kinetic model is developed for the free‐radical grafting of maleic anhydride MAH onto PP, taking into account that the reaction medium is heterogeneous due to the incomplete solubility of MAH in the polymer melt. Two different approaches are considered that derive from the limiting cases of very fast mass transfer (equilibrium) and no mass transfer between the two phases. The physical parameters considered in the model include the solubility of MAH in PP and the partition coefficient of the initiator between the two phases. The predictions of the models are in good agreement with experimental data taken from the literature for processes conducted under different conditions.magnified image

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