The optimization of Carreau model and rheological behavior of alumina/linear low-density polyethylene composites with different alumina content and diameter

The influence of alumina (Al ) content and diameter on the viscosity characteristics of the alumina/linear low-density polyethylene (Al /LLDPE) composites was discussed. The composites were fabricated by melt mixing with the two-rotor continuous mixer. The equivalent surface average particle diameter ( ) of Al was calculated by the scanning electron microscopic (SEM) images of samples. The steady-state and dynamic rheological measurements were used to study the evolution of viscosity parameters. With the Carreau model fitting to the steady-rate rheological data, zero-shear viscosity , time constant , and power law index of composites were obtained. On this basis, an optimized Carreau model was established by studying the changes of these parameter values. The rheological result presented that the parameter values ( , , and ) were linearly proportional to the filling content of Al particles for nano-Al /LLDPE composites. However, these parameters were, respectively, related to , , and for micron-Al /LLDPE composites.