A New Monte Carlo Simulation of Low-Density-Polyethylene Polymerization for Prediction of its Microstructure as a Result of Various Process Conditions

Abstract

In the petrochemical industries, a variety of low density polyethylene (LDPE) grades are produced from a single reactor line with changes in process conditions and/or materials. Herein the microstructure parameters, for example, monomer conversion, average molecular weight (), long chain branches (LCB) and short chain branches (SCB), are calculated for various process conditions in the polymerization process such as chain transfer agent (CTA) type and concentration, CTA feed position, initiator feed position, temperature profile, and residence time in the reactor, all based on industry data. Our results showed the CTA with a high rate constant makes three times more LCB but decreases the SCB by 13% relative to the CTA with a low rate constant. Also, for the same CTA type, decreased if the CTA concentration was increased. Injection of initiators at the beginning of the process had no significant effect on the SCB but increased the LCB by 54%. The new equations presented here to predict the microstructure of LDPE produced in tubular reactors resulted in good agreement with reported experimental values. The equations advantage is that the industrial data of the LDPE polymerization can be analyzed with high accuracy and speed to obtain the LDPE microstructure.