Key Words:dispersion; rheology; sharkskin
Abstract:The correlation between the sharkskin formation of polymers and the flow-induced dispersion of fillers is discussed. The rheological behaviors of low-density polyethylene (LDPE) and LDPE/TiO2 composites were investigated and analyzed based on the temperature dependence of critical points of the sharkskin formation. This examination revealed the influence of shear thinning on sharkskin behavior. The analysis indicated that the sharkskin formation of LDPE was governed by the mechanism of molecular absorption and de-absorption at the flow boundary, or by wall-slip at the polymeric layer with low viscosity. Sharkskin formation of LDPE occurs at different ranges of shear rates, depending on the mechanism in effect. In a further study, the shear-induced de-aggregation and dispersion of the TiO2 in LDPE was found to occur at a shear-rate range that was close to the range for sharkskin formations that are controlled by the adsorption mechanism.
Volume:45
Issue:5
Translation or Not:no