Some simulations on crystallinity in a typical linear low-density polyethylene

Crystallinity in ethylene/1-hexene copolymers, a type of linear low-density polyethylene, was investigated by Monte Carlo simulations. The comonomer distributions generated in the simulated chains and the melting temperatures of real chains were used to estimate the minimum crystallite thickness, which is the critical quantity for simulating crystallization in any type of polymer. Simulated values of this thickness were in good agreement with values calculated from Raman longitudinal acoustic mode (LAM) spectroscopy, except for very low 1-hexene mole fractions, where there were presumably complications from high melt viscosities and chain entanglements. The use of this information in estimating properties of these copolymers is illustrated by some preliminary results on the effects of varying amounts of this comonomer on the sizes and numbers of the polyethylene crystallites.