Bound Rubber as a Transferable Structural Descriptor: Connecting MD-Derived Interfacial Scaling to Continuum...

Area of Science:

• Polymer Science
• Materials Science
• Computational Chemistry

Background:

• Filled elastomers show a low-frequency power-law storage modulus (G-prime).
• Quantitative links between molecular interfacial structure and macroscopic reinforcement are not well understood.
• Existing models struggle to predict macroscopic properties from molecular details.

Purpose of the Study:

• To establish quantitative links between molecular interfacial structure and macroscopic reinforcement in filled elastomers.
• To develop a hierarchical multiscale framework integrating molecular dynamics (MD) and dynamic mechanical analysis (DMA).
• To improve the prediction of elastomer mechanical properties from molecular-level information.

Main Methods:

• Utilized a hierarchical multiscale framework combining coarse-grained molecular dynamics (MD) and dynamic mechanical analysis (DMA).
• MD simulations generated structural descriptors, including bound-layer scaling relations.
• Employed single-phase fractional Maxwell and dual-phase models for analyzing EPDM and PC/ABS data, respectively.
• Developed a regime-partitioned bridge model for cross-scale predictions, incorporating MD-derived baselines.

Main Results:

• MD simulations provided transferable structural descriptors, not direct rheology predictions.
• The dual-phase model was favored for larger datasets (PC/ABS, n=952).
• The regime-partitioned bridge model significantly reduced prediction error (7.3%) by incorporating MD structural priors and resolving uncaptured relaxation physics.
• Linear-viscoelastic constraints improved nonlinear predictions, reducing die-swell error by 87%.

Conclusions:

• The developed multiscale framework successfully links molecular interfacial structure to macroscopic elastomer reinforcement.
• This approach enhances the accuracy of predicting material properties and behavior.
• The findings offer a pathway for designing elastomers with tailored macroscopic properties based on molecular architecture.