Linear and nonlinear viscoelastic properties of bidisperse linear polymers: Mixing law and tube pressure effect
Predicted start-up extensional viscosities for the monodisperse linear polymer PS200 (see Table I), at strain rate of 0.001/s, with (—) and without (–) considering the Rouse correction.
Comparison between theoretical (—) and experimental storage and loss moduli of the monodisperse PS samples (from right to left) PS50, PS100, PS200, and PS390 (●) and the blends (from right to left) B1, B2 and B3 (◻).
Transient extensional viscosity at different strain rates. Comparison between theoretical (—) and experimental (○) results.
(a) Comparison between experimental (●) and theoretical (other symbols) steady elongational viscosity as a function of the strain rate for PS50K (◇), PS100K (x), PS200K (◼), and PS390K (○). All measurements performed at . The thin curves represent the predicted contribution from the orientation tensor S (i.e., imposing a value of 1 for ). The dotted lines represent the and for sample PS100. (b) Comparison between the prdicted maximum stretch (—) and the stretch value predicted in the steady regime (symbols) as a function of the strain rate, for the same samples.
Theoretical longest relaxation times (◼), stretch relaxation times , and tube diameter relaxation times (○) as a function of MW for samples PS50, PS100, PS200, and PS390.
Transient extensional viscosity of the blends B1 (a), B2 (b), and B3 (c) described in Table II, at different strain rates. Comparison between theoretical (—) and experimental (○) results. The dotted and dashed-dotted curves represent the contribution of the long and short components to the total viscosity, respectively. (d) Evolution of the stretch factor vs time, for the long (–) and the short (−) chains of sample B2, at different strain rates.
Steady elongation viscosity as a function of the strain rate: experimental (○) and theoretical (—) results. The predicted contributions of short (−) and long (—) chains are also shown, for (a) blends B1 and B2, and (b) blend B3.
(a) Steady extensional viscosity of blends B2 (black) and B3 (gray) as a function of the strain rate. Comparison between theoretical (thick continuous curves) and experimental results (B2:○; B3:◻). The dotted and the thin continuous curves represent, respectively, the contribution of the short and the long components to the total steady viscosity. (b) Transient extensional viscosity of the blends B2 (○, black curves) and B3 (x, gray curves) (see Table II), at a representative strain rate of 0.03/s. The thin continuous curves are the theoretical contributions of the long chains to the transient viscosity of the blends. The thick continuous curves represent the theoretical linear envelopes of the samples and are decomposed into the contribution from long (–) and short (…) chains.
Monodisperse PS samples: average molecular weight, polydispersity and main relaxation times.
Bidisperse PS samples: blend composition and tube diameter relaxation times of the short and long components.
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