Modelling of the butadiene and isoprene polymerization processes with a binary neodymium-based catalyst

Abstract In the present work we study the mechanism of the polymerization processes of isoprene and butadiene with the NdCl 3 ·3TBP–TIBA catalyst system (TBP=tributylphosphate, TIBA=triisobutylaluminium) using two mathematical models: one which takes into account a monomolecular termination and the other which considers that no termination reactions occur during the polymerization process. Both for isoprene and butadiene, by comparing with the experimental data, the best results were achieved from the equations derived in the frame of the polymerization model considering the absence of the termination reactions. The product between the rate constant of the propagation reaction and the active centres concentration depends mainly on the [Al]/[Nd] molar ratio used which is an argument for the participation of TIBA in the formation of the active centres.