Rheological properties of anionic polystyrenes. 7. Viscoelastic properties of six-branched star polystyrenes and their concentrated solutions

Abstract

The viscoelastic properties of six-branched star polystyrenes and their 50 wt % (0.641 g/mL) solutions were measured and compared with those of linear polystyrene. The dependence of zero-shear viscosity t/o and steady-state compliance J°u pon molecular weight was obtained. t?0 for six-branched polystyrene is lower than that for linear polystyrene of the same molecular weight. The values of J°for undiluted six-branched polystyrenes and their 50 wt % solutions depend on molecular weight even in the entanglement region. The J°values also follow the Rouse-Ham relation in the wide ranges of molecular weights; J°for star polymers exceeds that for linear ones at higher molecular weights. The entanglement compliance </eN°o f branched polystyrenes is the same as that of linear ones, suggesting no effect of branching on the entanglement spacing.

Viscoelastic properties of rubber-modified polymeric materials at elevated temperatures

“…On the other hand, it is also important that the rheological properties of only well characterized polymer-rubber particles systems are investigated so that general conclusions can be drawn on the viscoelastic properties of dispersed systems in molten states. To perform this kind of work, it is necessary to know the effects of molecular characteristics, such as molecular weight (24), molecular weight distribution (25,26), and branching (27)(28)(29) on the homogeneous polymer melts. With this information the universal effects of the mixing of the particles into the polymeric systems can be determined by measuring the rheological or viscoelastic properties of the well characterized rubber-modified polymer systems.…”

Temporal scaling analysis: Viscoelastic properties of star polymers

“…͑1͒-͑4͒. The agreement between each of the 11 examined 50 wt % solutions of six-arm star polystyrenes in Kaneclor 500, a partially chlorinated biphenyl, and determined GЈ() and GЉ() for polymers having 1.9ϫ10 5 рM w р1.02ϫ10 6 and 1.18рM w р1.32. These measurements covered six to seven orders of magnitude in frequency and four to five orders of magnitude in the moduli.…”

“…͑1͒-͑6͒ are tested against published experiments on solutions of star polymers and their linear homologs, including the results of Kajiura et al 8 and of Isono and Nagasawa 9 on poly-␣-methylstyrene three-arm stars and linear chains, those of Raju et al 10 on four-arm polybutadiene stars and other polymers, those of Masuda et al 11 on six-arm polystyrene stars, and those of Graessley et al 12 on linear and four-and six-arm polyisoprenes. Comparison is made with data 13-16 on linear polystyrenes and polybutadienes that have already 5,6 been successfully tested against the above equations.…”

Relationship between molecular characteristics and physical properties of linear low density polyethylenes

“…The zero-shear viscosities flo of branched polymer melts and the linear counterparts have been found to be successfully expressed (ref. 6,7,[9][10][11][12] by a unique line when those are plotted against the molecular dimension and/or intrinsic viscosity.…”