Solubility of Polyethylene in n-Hexane and Cyclohexane: Experimental Determination and Comparison with Solid–Liquid Equilibria-Based Predictions

In polyethylene (PE) production, the slurry process, in which the polymer is suspended as a slurry in a diluent, is particularly relevant. In the slurry state, partial solubilization of the polymer may occur. This may ultimately lead to wax formation, reactor fouling and polymer agglomeration. These issues may be alleviated by empirically adapting polymerization conditions, but a rational approach to that necessitates detailed information about polymer solubility. This information can be obtained through quantification of solid–liquid equilibria (SLE), which, in turn, necessitate input from experimental data. With an experimental setup for cloud point temperature determinations, the necessary data input was obtained to estimate the SLE of different PE (high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE)) in typical slurry process diluents. The cloud point temperatures predicted by the developed models were checked against experimental results. It was established that the behavior of solvent mixtures can be predicted based on that of their components.