Viscosity and Steady-State Compliance of Multi-Branched Star Polystyrenes

Ohta, Yasuhiko; Masuda, Toshiro; Onogi, Shigeharu

doi:10.1295/polymj.18.337

Cited by 6 publications

(4 citation statements)

References 47 publications

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“…Although the measurements include data taken over a wide range of temperatures, they are reduced to a common reference temperature of 25 °C using time-temperature superposition.43 From this procedure it was determined that the temperature dependence of polyisoprene stars is identical to that of linear polyisoprene, a result that agrees with earlier findings of This similarity is in contrast to that found for stars of hydrogenated polybutadiene and polyisoprene that have a temperature dependence different from linear species and more like that of polyethylene containing long branches. Further with , = 9.5 X 104 and 0 = 1.8 X 108.…”

Section: Resultsmentioning

confidence: 99%

Rheological behavior of star-shaped polymers

Fetters¹,

Kiss²,

Pearson³

et al. 1993

Macromolecules

358

331

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The rheological properties of star-shaped polyisoprenes having a wide range of arm numbers and arm molecular weights are reported. In contrast to linear polymers, stars have a broad relaxation spectrum and a viscosity that increases exponentially with arm molecular weight. A comparison of eight pairs of samples having 3 and 4 arms and identical arm molecular weights showed that the viscosity of 3-arm stars is approximately 20% lower. For higher degrees of functionality, 4 < f < 33, the effect of functionality saturates and the viscosity is determined by arm molecular weight only. The nonlinear properties of one sample were studied using step-strain tests and found to be essentially identical to those of linear polymers. The predictions of a molecular theory for star polymers based on an extension of the reptation model are reviewed and shown to be in good agreement with the experimental data.

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Section: Resultsmentioning

confidence: 99%

Rheological behavior of star-shaped polymers

Fetters¹,

Kiss²,

Pearson³

et al. 1993

Macromolecules

358

331

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show abstract

“…The method to evaluate the true values of gs 2 for multi-branched star polymers will be proposed in the succeeding paper. 32…”

Section: Characterization Of Star-shaped Polystyrenesmentioning

confidence: 99%

Characterization and Rheological Properties of Multi-Branched Star Polystyrenes

Masuda

Ohta

Yamauchi

et al. 1984

Polym J

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The star polymer samples were prepared by coupling narrow-distribution polystyryl anions with divinylbenzene and were characterized in terms of molecular weight, molecular weight distribution and coupling ratio. Dynamic viscoelastic properties of star-shaped polystyrenes having different molecular weights (M, = 1.3 20 x 10") and numbers (P= 7 39) of branches have been measured. The zero-shear viscosity '1o depends strongly upon the molecular weight at constant P, while it depends much less at constant M,. Molecular weight dependence of the steady-state compliance Je o are quite complicated. Je o increases with increasing molecular weight at constant P. When M, is constant, Je o is independent of molecular weight at P 7 and increases at P?. 7. Values of Je o are higher than those for the corresponding linear polymers. Relaxation spectra for star-shaped polystyrenes having many (P?. 15) branches exhibit a two-step change on the long-time side. These two sets of relaxation times are attributed to the relaxation mechanism associated with ordinary intermolecular entanglements and to that peculiar to branched polymers. The difference in the entanglement compliance for branched and linear polymers is smaller than that in Je o.

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“…been examined more extensively regarding synthetic polymers such as polystyrene and polyisoprene [13][14][15][16][17][18][19][20][21] . At the present time various types of branching -star, dendrimer, and comb -can be obtained at controlled degrees of branching and molecular weights.…”

Section: Effects Of Branching On the Rheological Properties Havementioning

confidence: 99%

Rheological Properties of Concentrated Solutions of a Branched Polysaccharide Dextran in an Ionic Liquid

Horinaka

Yamanaka

Takigawa

2019

J. Soc. Rheol., Jpn

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Rheological properties of dextran solutions in 1-butyl-3-methylimidazolium acetate were examined up to the concentration (c) of 4.1 × 10 2 kgm −3. A high molecular weight (≈ 2 × 10 6) dextran with a degree of divergence of 4 % was used. The zero-shear viscosity estimated from the flow behavior indicated that dextran chains in the solutions entangle each other at c ≥ 1.7 × 10 2 kgm −3. In fact the plateau modulus (G 0 N) was obtained from the G′ and G″ curves for c ≥ 2.6 × 10 2 kgm −3. However, the anomalous results were obtained regarding entanglement of dextran chains: The molecular weight between entanglements was constant against c at 2.3 × 10 4 , so that a large number of entanglements per chain was expected in spite of the subtle rubbery plateau that was actually observed. It was proposed that the dextran has the main structure of long branches and each branch is densely sub-branched.

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Viscosity and Steady-State Compliance of Multi-Branched Star Polystyrenes

Cited by 6 publications

References 47 publications

Rheological behavior of star-shaped polymers

Rheological behavior of star-shaped polymers

Characterization and Rheological Properties of Multi-Branched Star Polystyrenes

Rheological Properties of Concentrated Solutions of a Branched Polysaccharide Dextran in an Ionic Liquid

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