What does this research mean for the field?

In entangled polydisperse polyethylene melts under elongational flow, the coil-stretch transition is not sharp but distributed across the molecular ensemble due to chain-length-dependent disentanglement and decoupled chain dynamics. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To determine how realistic molecular-weight polydispersity affects the coil–stretch transition, structural segregation, and rheological properties of entangled polyethylene melts during planar elongational flow.

August 30, 2026Journal of Rheology

The coil–stretch transition and chain segregation in elongational flow of an entangled polydisperse polyethylene melt

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Authors

ETElyar TouraniUniversity of Tennessee at Knoxville MSMohammad Hadi Nafar SefiddashtiUniversity of Tennessee at Knoxville BEBrian J. EdwardsUniversity of Tennessee at Knoxville

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Implication

Simulation study demonstrates a distributed coil–stretch transition in polydisperse polyethylene melts, indicating chain length-dependent disentanglement governs flow behavior.

Key Points

To determine how realistic molecular-weight polydispersity affects the coil–stretch transition, structural segregation, and rheological properties of entangled polyethylene melts during planar elongational flow.
Conducted atomistic nonequilibrium molecular dynamics (NEMD) simulations of entangled polydisperse polyethylene melts with a realistic log-normal molecular-weight distribution under planar elongational flow.
Quantified steady-state chain conformational statistics, intermolecular interaction energies, elongational viscosity, and flow-induced birefringence across multiple deformation rates.
Polydispersity fundamentally replaces the sharp, monodisperse coil–stretch transition with a distributed transition where long chains unravel and disentangle at lower flow rates, while short chains remain partially coiled and entangled.
Macroscopic elongational viscosity displays a nonmonotonic dependence on the deformation rate, featuring an upward shift near Deborah number ≈ 1 driven by the combined stress contributions of heterogeneous chain lengths.
Intermolecular interactions become increasingly favorable during sequential stretching, with birefringence measurements confirming the divergence of conformational dynamics across the molecular ensemble.

Cite This Study

Tourani et al. (2026) studied this question.

synapsesocial.com/papers/6a93f07a6c1a8fb52e79cb3e https://doi.org/10.1122/8.0001253

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Implication

Simulation study demonstrates a distributed coil–stretch transition in polydisperse polyethylene melts, indicating chain length-dependent disentanglement governs flow behavior.

The coil–stretch transition and chain segregation in elongational flow of an entangled polydisperse polyethylene melt

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Implication

Key Points

Cite This Study

The coil–stretch transition and chain segregation in elongational flow of an entangled polydisperse polyethylene melt

Discussion

Member takes

Implication

Key Points

Cite This Study

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