Rheology and processability of polyamide66 filled with different‐sized and size‐distributed calcium carbonate

Two‐sized calcium carbonates (CaCO₃) were blended and filled into polyamide66 (PA66). The shear viscosity of PA66/CaCO₃ composites was measured with a capillary extrusion rheometer. The results showed that the shear viscosity of the efficient size distribution samples (PA66 was filled with 600/2500 mesh CaCO₃ blending) obviously decreased compared with that of the single‐size distribution samples (PA66 was filled with 600 or 2500 mesh CaCO₃). The shear viscosity of PA66/CaCO₃ composites at different temperatures was also studied. The results showed that the flow activation energy and flow activation entropy of the efficient size distribution samples obviously increased compared with those of the single‐size distribution samples. The change in flow activation entropy was used to explain the experimental results of shear viscosity. The processability of PA66/CaCO₃ composites was evaluated with a HAAKE torque rheometer. The results showed that the processability of the efficient size distribution samples was obviously improved and the best efficiency of processability improvement appeared in the 30 wt% CaCO₃ content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers