High-Pressure Polymerization of Ethylene in Tubular Reactors: Prediction of the Bivariate Distributions of Molecular Weight-Branches with a Rigorous Reactor Model

DIETRICH, MAIRA L.; SARMORIA, CLAUDIA; BRANDOLIN, ADRIANA; ASTEASUAIN, MARIANO

San Diego, California

Congreso; 13th International Symposium on Process Systems Engineering ? PSE 2018; 2018

PSE

Low-density polyethylene (LDPE) is a branched polymer whose processing and end-useproperties are mainly determined by the molecular weight distribution (MWD), the longchain branching distribution (LCBD) and short chain branching distribution (SCBD). Ingeneral, a suitable characterization of LDPE needs a simultaneous knowledge of thesethree distributions. This work presents a rigorous model of the high-pressure ethylenepolymerization in tubular reactors, capable of predicting the joint bivariate distributionsMWD-LCBD and MWD-SCBD, as well as monomer conversion and average molecularproperties. The bivariate distributions are modeled using the 2D probability-generatingfunction (2D pgf) technique. This deterministic technique allows a simple and efficientcalculation of the distributions, in spite of the complex mathematical description of theprocess. The reactor model is used to analyze the effect of different process and designvariables on the above mentioned joint distributions and on other properties of theproduct.