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.