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

Abstract The influence of alumina (Al 2 O 3 ) content and diameter on the viscosity characteristics of the alumina/linear low-density polyethylene (Al 2 O 3 /LLDPE) composites was discussed. The composites were fabricated by melt mixing with the two-rotor continuous mixer. The equivalent surface average particle diameter ( d ¯ A {\bar{d}}_{\text{A}} ) of Al 2 O 3 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 η 0 , time constant λ , and power law index n 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 ( η 0 , λ , and n ) were linearly proportional to the filling content of Al 2 O 3 particles for nano-Al 2 O 3 /LLDPE composites. However, these parameters were, respectively, related to d ¯ A {\bar{d}}_{\text{A}} , d ¯ A 2 {\bar{d}}_{\text{A}}^{2} , and d ¯ A 3 {\bar{d}}_{\text{A}}^{3} for micron-Al 2 O 3 /LLDPE composites.