Web Release Date: August 12,
Miscible Polymer Blend Dynamics: Double Reptation Predictions of Linear Viscoelasticity in Model Blends of Polyisoprene and Poly(vinyl ethylene)
and
Chemical Engineering Department and Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802
Received February 24, 2004
Revised Manuscript Received June 25, 2004
Abstract:
Predictions of the linear viscoelastic complex shear modulus in model miscible blends of
polyisoprene (PI) and poly(vinyl ethylene) (PVE) are compared with literature data. Using ideas of chain
connectivity, the effective monomer relaxation times of PI and PVE in the blend were calculated using
PI self-composition 
PI,s = 0.40 and PVE self-composition PVE,s = 0.80, determined in our earlier analysis
of segmental dynamics in PI/PVE blends. The reptation times of PI and PVE were then determined from
their effective monomer relaxation times in the blend, assuming a common tube for both components
(thus specifying the blend plateau modulus). The component reptation times and effective terminal
dispersion widths from fits to the pure component polymers were input along with the blend plateau
modulus to the des Cloizeaux "double reptation" model of polymer dynamics to make predictions of blend
linear viscoelasticity with no adjustable parameters. The calculated frequency dependence of the complex
modulus of PI/PVE blends was found to be in near quantitative agreement with experimental data,
including the experimentally observed thermorheological complexity.
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