Morphology and Rheological Behaviors of Polycarbonate/High Density Polyethylene in situ Microfibrillar Blends

Summary: Polycarbonate (PC)/high density polyethylene (HDPE) in situ microfibrillar blends were fabricated by a slit die extrusion, hot stretching, and quenching process. Despite PC and HDPE having a high viscosity ratio, which is usually disadvantageous to fibrillation, the morphological observation indicated that the blends had well‐defined PC microfibrils. The size and amount of the PC fibrils were nonuniform through the thickness of the extrudate, and were also affected by the PC concentration and hot stretch ratio. There were coarse and dense fibrils in the core zone, while these fibrils became finer and reduced in number toward the surface. The melt flow rate (MFR) of the PC/HDPE microfibrillar blend decreased with the increase of PC concentration, but increased with the larger hot stretching rate (or hot stretching ratio, HSR). Besides, it was found that the fibrillar blend had better flowability than the common blend with spherical particles at the same PC concentration. Temperature was also an important factor influencing the MFR due to the temperature dependence of PC and HDPE viscosity, and the PC phase morphology. The PC microfibrils could not be preserved beyond 230 °C and transformed into spherical particles. The rheological behaviors at various shear rates were studied by capillary rheometer. The orientation of PC fibrils and HDPE molecules with higher shear rate led to a decrease in the viscosity of microfibrillar blend. The data obtained in this study can help construct the technical foundation for recycling and utilization of PC and HDPE waste by manufacture of microfibrillar blends in future work. SEM micrograph of the PC/HDPE microfibrillar blend. image SEM micrograph of the PC/HDPE microfibrillar blend.