Elongational Viscosity

Determined via the Cogswell convergent flow model. Elongational viscosity, or the resistance to elongation is known to be sensitive to material structure (MWD and chain branching). Dissimilar MWD can often be resolved in radioactive and peroxide cross-linked LLDPEs that other techniques (shear viscosity and MFI) are blind to. Branching differences, such as those seen in HDPE and LDPE, can also be differentiated as can changes due to catalyst type using this measurement.