Melt flow behavior in capillary extrusion of nanometer calcium carbonate filled PCL bio-composites

摘要

Nanosized calcium carbonate (nano-CaCO _3) filled polycaprolactone (PCL) bio-composites were prepared by using a twin-screw extruder. The melt flow behavior of the composites, including the entry pressure drop, melt shear flow curves and melt shear viscosity, were measured through a capillary rheometer operated in a temperature range of 170～200 °C and shear rates varying from 50 to 10 ~3 s ~(-1). The entry pressure drop showed a non-linear increase with increasing shear stress when the filler weight fraction was less than 3%, while it decreased slightly with an increase of shear stress at a filler weight fraction of 4%. The melt shear flow roughly followed a power law, while the effect of temperature on the melt shear viscosity was estimated by using the Arrhenius equation. Moreover, the influence of the nano-CaCO _3 on the melt shear viscosity of the PCL composite was not significant at low filler levels.