The Phase Morphology And Viscoelastic Properties Of Polypropylene/Ethylene-1-octene Copolymer Blends

The phase morphology development, viscoelastic rheological and thermodynamic properties of the blends of polypropylene (PP) and ethylene-1-octene copolymer (EOC) as an experiment part of polymer multi-scale seamless research were studied. Scanning Electron Microscopy (SEM), Back Small Angle Laser Scattering (BSALS), Differential scanning calorimetry (DSC), Rotational rheometer were used in the research of PP/EOC blends.The influences of blend composition and processing conditions (mixing time, rotor speed and mixing temperature) on phase morphology development of the blends were investigated by scanning electron microscopy (SEM) in internal mixer. Moreover, the effect of blend composition and screw rate on the phase morphology in the extruder and the phase morphology of the blends at different locations along the extruder length were investigated by SEM in detail. The experiment result showed the rule of phase morphology evolution of the blends, and the effect of viscoelastic rheological and thermodynamic properties on the rule are given.The solidification process of the blends in internal mixer is investigated by SEM and Back Small Angle Laser Scattering (BSALS). The result showed phase coalescence occurred in the normal cooling process.DSC was used to get the thermodynamic properties of PP/EOC blends. The effect of blend composition on melting, crystallization behaviors and the Tg curve of the blends is studied, The result showed that the two components are partial miscible.Rotational rheometer was used to study the viscoelastic rheological properties of PP/EOC blends. The effect of shear stress, temperature, dynamic frequency on the linear viscoelastic properties of the blends have been investigated in the molten state. The blends with 10-95 wt% PP exhibit phase-separated morphology at 190-250℃, Palierne emulsion model is used to relate the phase morphology and the viscoelastic rheological properties of PP/EOC blends, and the effect of phase morphology on the viscoelastic properties of blends is investigated. Moreover, the phase diagram of the blends system is studied by viscoelastic rheological properties, and the factors influenced the phase diagram is analyzed in the blends system.