Ultrasonic Oscillations Effect on Extrusion Processing, Structure, and Properties of Blends of Propylene Based Plastomer and Ethylene/1-Octene Copolymer

The effects of ultrasonic oscillations on extrusion processing, phase morphology, and compatibility as well as mechanical properties for blends of propylene based plastomer (DP) and ethylene/ 1-octene copolymer (EOC) were examined. The results show that introduction of ultrasonic oscillations into polymer melts in extrusion can in situ improve their processability, including the reduction of die pressure and shear viscosity under a constant shear rate (flow rate) and the increase of throughput under the same shear stress (die pressure). Scanning electron microscopy observation reveals that with ultrasonic oscillations, morphology of reduced disperse phase (EOC) size and good interfacial adhesion between EOC and DP matrix are formed in DP/EOC blends. The interfacial tension between DP and EOC melts obtained from the Palierne emulsion model decreases with applying ultrasonic oscillations. FTIR and GPC analysis indicate that in situ copolymer formation between DP and EOC happens with ultrasonic oscillations and copolymer consequently acts as compatibilizer for the blends. Accordingly, it leads to an elevation of stress at break and elongation at break of the blends.