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

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