IMMISCIBILITY OF POLY(ETHYLENE) AND POLY(PROPYLENE) - MOLECULAR-DYNAMICS STUDY

In this article, we report the results of molecular dynamics simulatio ns for models of poly(ethylene), isotactic poly(propylene), and mixtur es of the two to understand the possible origin of melt state incompat ibility. At temperatures well above the crystal melting points of the homopolymers, isolated poly(ethylene) and poly(propylene) chains forme d high-density collapsed states. The poly(ethylene) and poly(propylene ) chains were found to segregate into distinct domains even when the i nitial state was highly interpenetrating. The poly(ethylene) phase sho ws a significant amount of focal order at the simulation temperature. In the case of poly(propylene), some helical segments were found in th e collapsed structure. We speculate that the immiscibility of these tw o nonpolar polymers, in the melt state, may be due to the differences in local morphology that are present in the melt state.