The impact of viscoelastic behavior and viscosity ratio on the phase behavior and morphology of polypropylene/polybutene-1 blends

In this study, the influence of the viscosity ratio on the rheology, morphology, and interfacial interaction of polypropylene and polybutene-1 (PB-1) resins with various melt flow behaviors in the blend are investigated. A droplet-matrix morphology is observed in the scanning electron microscope images for all formulations and the size of particles increased proportionally by increasing the viscosity ratio. Viscoelastic parameters of blends at various viscosity ratios and compositions are measured by small-amplitude oscillation rheometry in the linear viscoelastic region. The Cole-Cole plots showed a nearly semicircular arc for all compositions. This semicircular arc is observed while the viscosity ratio is lower than 1, and the Cole-Cole plots deviated from the semicircular shape at PB-1 content higher than 10 wt%. It is emphasized that, in addition to compatibility, the semi-circularity of Cole-Cole plots affects the size of the dispersed particles, which is under the influence of the viscosity ratio. It is found that the interfacial tensions of polypropylene and PB-1 are not significantly different when changing the viscosity ratio and coarsening the morphology. The form relaxation times in the blends with lower viscosity ratios are shorter than the form relaxation times of the blends with higher viscosity ratios. J. VINYL ADDIT. TECHNOL. 21:94-101, 2015. (c) 2014 Society of Plastics Engineers