Melt flow behavior in capillary extrusion of nanosized calcium carbonate-filled poly(L -lactic acid) biocomposites

摘要

Nanosized calcium carbonate (nano-CaCO 3)-filled poly-L-lactide (PLLA) biocomposites were compounded by using a twin-screw extruder. The melt flow behavior of the composites, including their entry pressure drop, melt shear flow curves, and melt shear viscosity were measured through a capillary rheometer operated at a temperature range of 170-200°C and shear rates of 50-10 3 s -1. The entry pressure drop showed a nonlinear increase with increasing shear stress and reached a minimum for the filler weight fraction of 2% owing to the "bearing effect" of the nanometer particles in the polymer matrix melt. The melt shear flow roughly followed the power law, while the effect of temperature on the melt shear viscosity was estimated by using the Arrhenius equation. Hence, adding a small amount of nano-CaCO 3 into the PLLA could improve the melt flow behavior of the composite. POLYM. ENG. SCI., 52:1839-1844, 2012.