Molecular weight distribution modeling of LDPE in a continuous stirred-tank reactor using coupled deterministic and stochastic approach

A hybrid approach that combines the method of moments and Monte Carlo simulation to predict the molecular weight distribution of low-density polyethylene for a continuous stirred tank reactor system is proposed. A 'Block', which is repeating reaction group, is introduced for the calculation cost-effective simulation. This model called the 'block Kinetic Monte Carlo' is similar to 10 to 32 times faster than Neuhaus's model. The model can be applied to any steady state system and provide a calculation cost reduction effect, where one reaction is much faster than others, for example, the propagation reaction. Furthermore, we performed a case study on the effects of the system temperature and initiator concentration on the MWD and reaction rate ratio. Based on the simulation results of 180 case studies, we determined a quantitative guideline for the appearance of shoulder, which is a function of the rate ratio of reactions to the propagation reaction.