Macromolecules, Vol.44, No.13, 5401-5413, 2011
Correlations between the Characteristic Rheological Quantities and Molecular Structure of Long-Chain Branched Metallocene Catalyzed Polyethylenes
Different rheological quantities, such as the zero shear-rate viscosity eta(0) and the linear steady-state elastic compliance L of long-chain branched metallocene-catalyzed ethene homopolymers and ethene-/alpha-olefin copolymers with a polydispersity M(w)/M(n) approximate to 2, were correlated with the molar mass A, and degree of long-chain branching lambda. A linear reference for the delta(vertical bar G*vertical bar) plot was used to show the effect of long-chain branches on this rheological property. The linear steady-state elastic compliance L correlated with the zero shear-rate viscosity increase factor eta(0)/eta(lin)(0) and the characteristic phase angle delta(c). However, the latter only works when compensating for the influence of the molar mass on J(e)(0) by the relationship between J(e)(0) and M(w) established elsewhere (Stadler and MUnstedt, JoR, 2008). The characteristic phase angle 6, and zero shear-rate viscosity enhancement factor eta(0)/eta(lin)(0) are linked to each other by the linear dependencies for the type I and type II viscosity functions.