Molecular dynamics studies of the thermodynamics of HDPE/butene-based LLDPE blends

Hildebrand solubility parameters (delta) at elevated temperatures were comp uted for models of high-density polyethylene (HDPE) and a series of butene- based linear low-density polyethylene (b-LLDPE) with different branch conte nts using molecular dynamics simulation. And the delta values were then use d to calculate the corresponding Flory-Huggins interaction parameter (chi) between HDPE and various b-LLDPE models. The results indicate that the leve l of branch content of b-LLDPE that is required to phase separate the blend s in the liquid state is about 40 branches/1000 backbone carbons, regardles s of temperature. This is consistent with the recent small angle neutron sc attering (SANS) findings of Alamo et al. [Macromolecules 1997;30.561-566]. (C) 2000 Elsevier Science Ltd. All rights reserved.