Predictive relation for the α-relaxation time of a coarse-grained polymer melt under steady shear

Abstract

We examine the influence of steady shear on structural relaxation in a simulated coarse-grained unentangled polymer melt over a wide range of temperature and shear rates. Shear is found to progressively suppress the α-relaxation process observed in the intermediate scattering function, leading ultimately to a purely inertially dominated β-relaxation at high shear rates, a trend similar to increasing temperature. On the basis of a scaling argument emphasizing dynamic heterogeneity in cooled liquids and its alteration under material deformation, we deduce and validate a parameter-free scaling relation for both the structural relaxation time τα from the intermediate scattering function and the “stretching exponent” β quantifying the extent of dynamic heterogeneity over the entire range of temperatures and shear rates that we can simulate.

Rheological Behavior of Polymer Nanocomposites Filled with Spherical Nanoparticles: Insights from Molecular Dynamics Simulation

“…. 22 Here, q is the momentum transfer describing the spatial scale; N is the number of polymer beads; [rj(t)rj(0)] is the displacement of atom j within the time t. The q is chosen to be q0=6.9 which reflects the segmental relaxation approximately corresponding to the maximum peak of the static structure factor. Figure S6 .…”

“…Figure S6 . 22 A and τf are the additional fitting parameters represent a fast  -relaxation; the βf and β are the stretching exponent;   is the  -relaxation time. The  -relaxation process is nearly unaffected by the γ̇.…”

“…[13][14][15][16][17] The complex rheological behavior is reported to be related the structure change of polymer chains 14,17,20,48 and the heterogeneous dynamics under the shear flow. [21][22][23] In this work, we focused on the rheological property of PNCs by mainly analyzing the evolution process of both the NP network and the polymer-NP network in details, which is the main difference with these works. At last, the relaxation time   of chains is calculated Fig.…”

“…Furthermore, the  -relaxation process is progressively suppressed by the shear flow. 22 Meanwhile, the scaling laws are established for the motion of polymer molecules.…”

Development of Coarse-Grained Models for Poly(4-vinylphenol) and Poly(2-vinylpyridine): Polymer Chemistries with Hydrogen Bonding

“…CG polymer models reduce the degrees of freedom by representing a polymer as a string of CG beads, where each CG bead represents either groups of atoms within a monomer, a whole monomer, or groups of monomers (or Kuhn segments). CG simulations have been used extensively to predict universal properties of polymers [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] or properties/behavior exhibited by specific polymer chemistries, enabling direct comparison to experiments [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ].…”