Linear rheology of diluted linear, star and model long chain branched polymer melts

Daniels, D. R.; Mcleish, T. C. B.; Kant, Rama; Crosby, B.J.; Young, R. N.; Pryke, Andrew; Allgaier, Jürgen; Groves, D. J.; Hawkins, Rhoda J.

doi:10.1007/s003970100175

Cited by 45 publications

(40 citation statements)

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“…Viscoelastic studies on combs reported in literature have been mostly conducted on combs that contained a very low number of branches per backbone (6e8 [43], 5e31 [44], 5e 23 [11] and 30 branches [9]) whereas the combs considered here contained 46e136 branches per backbone chain. For example, in a polyBMA comb consisting of a backbone with M n ¼ 9:5 Â 10 4 and containing 20% branching with branch M n ¼ 2:5 Â 10 4 , the backbone only constitutes 2.8% of the molecular weight.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Thermal and viscoelastic structure–property relationships of model comb-like poly(n-butyl methacrylate)

Vosloo

Zyl

Nicholson

et al. 2007

Polymer

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Section: Mechanical Propertiesmentioning

confidence: 99%

Thermal and viscoelastic structure–property relationships of model comb-like poly(n-butyl methacrylate)

Vosloo

Zyl

Nicholson

et al. 2007

Polymer

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“…[4][5][6][7][8][9][10] However, more complex architectures have received greater attention only recently. [11][12][13][14][15] The difference in the mechanism for relaxation of branched molecules from that of linear ones was indicated by their profoundly different viscoelastic properties in early studies. 16 Contrary to linear chains, branched polymers impose significant constraints for molecular motions realized through the existence of a permanent (chemical) cross-link, the branch point.…”

Section: Introductionmentioning

confidence: 99%

Role of Architecture on the Conformation, Rheology, and Orientation Behavior of Linear, Star, and Hyperbranched Polymer Melts. 1. Synthesis and Molecular Characterization

Kharchenko¹,

Kannan²,

Cernohous³

et al. 2002

Macromolecules

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In the preceding publication, we showed that the hyperbranched polystyrenes (HBPS) synthesized as part of this study may be viewed as starlike molecules with a high branch density, which are either unentangled or weakly entangled. In this paper, the role of architecture, especially the branch density, on the rheological and orientation behavior is investigated using simultaneous, quantitative stress and flow birefringence measurements in the melt state. Linear PS and eight-arm symmetric PS stars follow the stress-optical rule (SOR) over a wide dynamic range, with the stress-optical coefficient (C) governed by the arm molecular weight. When the branch density is "moderate" (greater than ∼20 arms), there is only a hint of nonterminal behavior in the viscoelastic moduli, while the C drops by 30% compared to a star with eight arms of comparable length. When the branch density is "high" (∼50 arms), and the arms are unentangled, the nonterminal behavior in G* is clearly apparent, and there is a dramatic breakdown in the stress-optical rule in these homopolymer melts. The quantitative birefringence measurements suggest that the "excess" birefringence may be due to the "form" contributions from the core-shell structure. Such a structure may be formed by the preferential radial stretching of the chain segments near the core, as suggested by other studies on hyperstars. For comparable chain density, the core would be bigger than the shell when the arm length is smaller. Therefore, the 5K-HBPS exhibits a more severe breakdown compared to the 10K-HBPS.

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“…† itselfÐto reconstruct Figure 11. Comparison of G 0 and G 00 for monodisperse linear (broken lines) and star (continuous lines) polyisoprene melts [118]. The linear molecule and the span of the star molecule both comprise about 40 entanglements.…”

Section: T C B Mcleish 1402mentioning

confidence: 99%

Tube theory of entangled polymer dynamics

McLeish

2002

Advances in Physics

836

1,122

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The dynamics of entangled¯exible polymers is dominated by physics general to many chemical systems. It is an appealing interdisciplinary ®eld where experimental and theoretical physics can work closely with chemistry and chemical engineering. The role of topological interactions is particularly important, and has given rise to a successful theoretical framework: the`tube model'. Progress over the last 30 years is reviewed in the light of specially-synthesized model materials, an increasing palette of experimental techniques, simulation and both linear and nonlinear rheological response. Our current understanding of a series of processes in entangled dynamics:`reptation',`contour length¯uctuation' and`constraintrelease' are set in the context of remaining serious challenges. Especial attention is paid to the phenomena associated with polymers of complex topology or`long chain branching'.

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Linear rheology of diluted linear, star and model long chain branched polymer melts

Cited by 45 publications

References 0 publications

Thermal and viscoelastic structure–property relationships of model comb-like poly(n-butyl methacrylate)

Thermal and viscoelastic structure–property relationships of model comb-like poly(n-butyl methacrylate)

Role of Architecture on the Conformation, Rheology, and Orientation Behavior of Linear, Star, and Hyperbranched Polymer Melts. 1. Synthesis and Molecular Characterization

Tube theory of entangled polymer dynamics

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