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

Area of Science:

• Polymer Physics
• Materials Science
• Computational Soft Matter

Background:

• Understanding structural relaxation is crucial for polymer melt behavior.
• Dynamic heterogeneity significantly impacts the relaxation processes in cooled liquids.
• Deformation can alter the complex dynamics of polymer systems.

Purpose of the Study:

• To investigate the effect of steady shear on structural relaxation in polymer melts.
• To explore the relationship between temperature, shear rate, and relaxation dynamics.
• To develop a predictive scaling relation for polymer dynamics under shear.

Main Methods:

• Simulated coarse-grained unentangled polymer melt.
• Analysis of the intermediate scattering function.
• Application of scaling arguments based on dynamic heterogeneity.

Main Results:

• Steady shear progressively suppresses the alpha-relaxation process.
• High shear rates lead to inertially dominated beta-relaxation, mirroring high-temperature effects.
• A parameter-free scaling relation accurately predicts structural relaxation time (τ_α) and stretching exponent (β).

Conclusions:

• Shear flow significantly modifies polymer melt dynamics, akin to thermal effects.
• The developed scaling relation provides a universal description of polymer relaxation under deformation.
• This work offers insights into the fundamental physics of soft materials under flow.