2026/03/31 by Takahiro Murashima, Katsumi Hagita, Toshihiro Kawakatsu
Chemical Engineering · Materials Science · Physics and Astronomy · #Material Dynamics and Properties #Polymer crystallization and properties #Rheology and Fluid Dynamics Studies #cond-mat.soft
paper · pdf · doi:10.1021/acs.macromol.6c00881
published as Macromolecules (2026) vol. 59, pp. 8304-8320 · 45 pages, 11 figures, 2 tables
arxiv created 2026/07/13 · openalex publication_date 2026/07/13 · openalex created_date 2026/07/14 · arxiv updated 2026/07/30 · openalex updated_date 2026/07/30
The rheological behavior of ring-linear polymer blends under uniaxial elongational flow has remained a subject of intense debate, particularly regarding the emergence of stress overshoot. Herein, we employ coarse-grained molecular dynamics simulations to investigate the chain-length dependence of elongational viscosity in 1:1 ring-linear blends of flexible chains with the equal molecular weight. Our results reveal a distinct threshold in the degree of threading, quantified by the number of entanglements Z = N /Ne (where N is the number of beads per chain and Ne is the entanglement chain length), for the appearance of stress overshoot: while blends with shorter chains (Z ≤ 2) exhibit monotonic stress growth, a clear stress overshoot emerges when the chain length reaches a threshold value (Z ≈ 4). Consistent with previous reports, this overshoot originates from a thread-to-unthread transition. At the threshold chain length, multiple linear chains penetrate a single ring, providing sufficient topological constraints to significantly stretch the ring under elongational flow. We predict that this transition can be experimentally validated via 2D small-angle neutron scattering patterns in the plane of the stretching and perpendicular directions, offering a direct structural signature of the ring recoil process for future experimental verification.