Mathematical modeling of 1,3-butadiene polymerization over a neodymium-based catalyst in a batch reactor with account taken of the multisite nature of the catalyst and chain transfer to the polymer

Kinetic heterogeneity of neodymium catalyst systems modified with methylaluminoxane

“…And other mecha nisms that limit the growing chain (including the chain transfer to polymer, which does not change the average MW of the polymer) are possible. The observed decrease in the reduced velocity of the poly merization reaction is likely due to the deactivation or interconversion of AC [5].…”

Calculating and analyzing the molecular weight distribution of a polymer synthesized over a multisite catalyst in a cascade of stirred reactors

“…The kinetic scheme of polymerization includes ini tiation (instantaneous); chain propagation on two types of ASs (AS I, AS II); chain transfer to the monomer, polymer, and organoaluminum compound; and the conversion of AS I to AS II ( ) [5]. It is assumed that there is no AS deactivation (or the termination of a kinetic chain) in the system under investigation.…”

“…Equation (5) describes the variation of R k (i, j, l) as a result of the supply of the appropriate macromole cules to the kth reactor with the inlet stream; the with drawal from the reactor with the outlet stream; the chain propagation on two types of ASs; the chain transfer to the monomer, organoaluminum com pound, and polymer; the conversion of AS I to AS II; and the reinitiation. Equation (5) is written in the approximation of long chains, which is used for high molecular polymers.…”

“…The moments of polymer MWD are generally determined as follows. The generating function [5,6] is introduced, and an equation for this function is derived by multiplying each of the terms in Eq. (5) by s i q j e -p , summing over i and j, and integrating with respect to l. Then, formulas for calculating the statisti cal moments of MWD are obtained by differentiating the equation for the function F the necessary number of times with respect to s, q and p. If we introduce the designation from the definition of MWD moments, we have ; in particular, is the number of polymer chains per unit volume of the kth reactor, is the quantity of the produced polymer per unit volume of the kth reactor, and The current Mathematica package for symbolic computing makes it possible to directly solve the sys tem of equations (1)-(5) and construct the distribu tions of macromolecules in the number of ASs and the degree of polymerization at the outlet of the kth reac tor of the cascade for a two centered catalyst under conditions of chain transfer to the polymer and arbi trary temperature distribution along the reactors of the cascade.…”

Modeling of 1,3‐Butadiene Solution Polymerizations Catalyzed by Neodymium Versatate

“…Manuiko et al developed a model for 1,3‐butadiene solution polymerizations that takes into account the presence of two types of active sites in the system and the presence of hexachloro‐p‐xylene as a chlorinating agent. Particularly, their model was able to calculate average molecular weights and branching frequencies.…”