Prediction of Molecular Weight Distribution and Long-Chain Branching Distribution of Low-Density Polyethylene from a Kinetic Model

The molecular weight distribution and the long-chain branching distribution of low-density polyethylene are predicted as a function of the synthesis conditions from a kinetic model for an autoclave reactor. The model includes initiations, propagation, termination by combination and disproportionation, and chain transfer to monomer, solvent, and polymer. Recursion formulas are developed to calculate the whole distribution density functions. A numerical method for solving the model equations is proposed. Several simulations have been performed to demonstrate the method, and predictions of long-chain branching distributions of an industrial autoclave reactor are compared with laboratory measuements.