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Mathematical Modeling of the Molecular Weight Distribution in Low Density Polyethylene. I. Steady‐State Operation of Multizone Autoclave Reactors
Author(s) -
LópezCarpy Bruno,
SaldívarGuerra Enrique,
ZapataGonzález Iván,
GarcíaFranco César
Publication year - 2018
Publication title -
macromolecular reaction engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 32
eISSN - 1862-8338
pISSN - 1862-832X
DOI - 10.1002/mren.201800013
Subject(s) - low density polyethylene , autoclave , molar mass distribution , dispersity , steady state (chemistry) , materials science , polyethylene , continuous stirred tank reactor , moment closure , constant (computer programming) , polymer , thermodynamics , chemistry , polymer chemistry , computer science , physics , organic chemistry , composite material , turbulence , programming language , metallurgy
A comprehensive mathematical model and an efficient strategy for its solution are presented to describe the complete molecular weight distribution (MWD) in the free‐radical polymerization for the production of low density polyethylene (LDPE) in continuous stirred tank reactors at steady state. The kinetic scheme includes all the relevant reactions that affect the MWD. The solution for the complete MWD is given as explicit algebraic expressions that are solved sequentially taking advantage of the algebraic structure of the equations; the strategy can simulate LDPE multizone autoclave reactors in a simple and straightforward manner. No approximation for the moment's closure is used. Model simulations reasonably match average molecular weight data from an industrial plant, as well as results from the POLYRED software. A parameter sensitivity study for key kinetic constants shows that the MWD polydispersity is predominantly affected by the transfer to polymer rate constant. The solution is applied to linear, topological and mechanical chain‐scission mechanisms.