Regensburg 2025 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Modeling and Simulation of Soft Matter II

CPP 21.6: Vortrag

Dienstag, 18. März 2025, 15:15–15:30, H34

Load-induced shear band formation in microscale epoxy materials — •Julian Konrad, Janina Mittelhaus, Bodo Fiedler, and Robert Meißner — Hamburg University of Technology

Thin epoxy films (≈ 30 µm) exhibit unexpected ductile behavior under mechanical load, challenging the conventional view of thermoset materials as inherently brittle. This behavior is characterized by the formation of shear bands, as revealed by mechanical testing and infrared spectroscopy. Analysis of vibrational spectra shows redshifts in para-phenylene stretching vibrations due to bond elongation, and blueshifts in out-of-plane hydrogen vibrations, resulting from polarization effects in the aromatic backbone. Molecular dynamics simulations support these findings, revealing a cascade of molecular realignments driven by deformation. Notably, these structural changes are reversible upon heating, suggesting a form of frozen entropy elasticity rather than plasticity. To further investigate, we employed a novel method using the MACE neural network potential to compute vibrational spectra with ab initio accuracy. This approach captures strain-dependent spectral shifts, accounts for interface and size effects, and highlights key implications for the design of composite materials.

Keywords: Epoxy films; Ductility; Shear bands; Molecular Dynamics; Infrared Spectroscopy