Rheology, Morphology, and Mechanical and Thermal Properties of Blends of Propylene Based Plastomer and Ethylene/1-Octene Copolymer

Abstract

Blends of propylene based plastomer (DP) and ethylene/1-octene copolymer (EOC) of various concentrations are prepared by a melt-blending process at 160°C, using a corotating twin-screw extruder. The rheology, phase morphology, and mechanical and thermal properties of DP/EOC blends are investigated. The results show that addition of DP in EOC can lead to significant improvement of mechanical properties, including yield strength, strength at break, and Young's modulus, concomitant with the reduction of melt viscosity. The experimental data for melt viscosity and elongation at break respectively display a positive deviation from additivity, indicating the enhancement of the component interaction and superior interface properties between DP and EOC phases. The transition from plastic to elastomeric properties coincides with phase inversion. At this 85/15 DP/EOC composition, the decrease in the viscosity of DP matrix enhances EOC dispersed phase size, due to the increase in their viscosity mismatch. DSC analysis shows that the melting temperature of DP and EOC phases in blends remains constant irrespective of the composition, respectively. The nucleation effect of EOC on DP tends to increase the crystallization temperature of DP phase. It is also verified that the EOC phase can be prevented from crystallizing with increasing DP content in the blends.