Shear and elongational rheology of polyethylenes with different molecular characteristics. II. Elongational rheology |
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| Authors: | X Wei J R Collier S Petrovan |
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| Affiliation: | 1. Unilever, 40 Merritt Boulevard, Trumbull, Connecticut 06611;2. Chemical and Biomedical Engineering, Florida Agricultural and Mechanical University/Florida State University, Tallahassee, Florida 32320;3. Chemical Engineering Department, University of Tennessee, Knoxville, Tennessee 37996‐2200 |
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| Abstract: | The elongational viscosities of polyethylenes with different molecular characteristics were measured at different Hencky strains and temperatures with a capillary rheometer by the replacement of the capillary cylindrical die with a hyperbolic converging die. The hyperbolic shape of the die established a purely elongational flow field at a constant elongational strain rate throughout the die. The effects of molecular characteristics such as the molecular weight, molecular weight distribution, and long‐chain branching and processing conditions such as the temperature and Hencky strain on the elongational rheology of the polyethylene samples were studied. Good master curves were generated for temperature and Hencky strain shifting and simultaneous shifting with respect to both the temperature and Hencky strain. Both the molecular weight distribution and long‐chain branching seemed to promote strain rate thinning and reduce the elongational viscosity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1184–1194, 2007 |
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| Keywords: | molecular weight distribution/molar mass distribution polyethylene (PE) elongational processing rheology long‐chain branching (LCB) viscosity |
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