Role of intramolecular energy on polyolefin miscibility: Isotactic polypropylene/polyethylene blends

Self-consistent polymer reference interaction site model (PRISM) and molecular dynamic (MD) calculations on a blend of isotactic polypropylene and polyethylene for several compositions and chain lengths were performed. It was observed that slight conformational changes occur in the chains upon entering the blend. These changes result in a significant intramolecular contribution to the mixing energy primarily thorough torsional and van der Waals potentials. According to this, it was found that it was necessary to consider both intra- and inter-molecular energies in order to obtain quantitative estimates of thermodynamic properties of polyolefin blends.