Rheological Behaviors and Molecular Weight Distribution Characteristics of Bimodal High-Density Polyethylene

A series of bimodal high density polyethylene (PE) with different molecular weight distributions (MWDs) were prepared by melt blending, and the fitting multipeaks on Gaussian were used to analyze the MWD curves, and the ratio of the areas under unimodal curves was as a tool to characterize the MWD; the phase behaviors and rheological behaviors were studied by dynamic rheological. The results showed that homogeneous bimodal high density PEs could be successfully prepared via melt blending, and the bimodal characteristic could be adjusted as expected. For samples with the MWD peak positions unvaried, the storage modulus, complex viscosity, and zeroshear viscosity decreased rapidly with the value of A(L/U) increasing. Especially in the low frequency region, the loss modulus surpassed the storage modulus (G '' > G') when A(L/U) > 10.17 and the dynamic cross-point Gx appeared and increased with increasing A(L/U), with an increasing extent much larger than that due to the width of MWD. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1543-1549, 2011