ABSTRACT:Creep experiments have been applied to probe the zero-shear viscosity, g 0 , of polyethylene chains directly and precisely in a constant-stress rheometer at 190 C. Such experiments, when combined with precise measurements of the weight-average molecular weight, M w , calibrated relative to linear chains of high-density polyethylene, are shown to provide a very sensitive approach to detect low levels (0.005 branches per 1000 carbons) of long-chain branching (LCB). This detection limit is shown to be insensitive to whether the molecular weight distribution (MWD) breadth, M w /M n , rises from about two to ten.
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