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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Polymer and Molecular Dynamics, Friction and Rheology

CPP 8.1: Talk

Monday, March 18, 2024, 15:00–15:15, H 0107

Viscoelastic response of cross-linked epoxy using non-affine lattice dynamics: Bridging the timescale gap — •Vinay Vaibhav1, Timothy W. Sirk2, and Alessio Zaccone11Department of Physics "A. Pontremoli", University of Milan, Via Celoria 16, 20133 Milan, Italy — 2Polymers Branch, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005, USA

There is a vast timescale disparity, at least six orders of magnitude, at which mechanics can be probed in simulations compared to experiments. The theoretical approach, known as Non-affine Lattice Dynamics (NALD), developed by solving the equation of motion for the non-affine displacement in a disordered environment [1], has been promising in predicting the mechanics of amorphous solids at lower frequencies, making it possible to access the experimental timescales. We use large-scale computer simulations to model an epoxy system comprised of diglycidyl ether of bisphenol A (DGEBA) cross-linked by poly(oxypropylene) diamine [2], and calculate the viscoelastic response using NALD at different frequencies and also via molecular dynamics simulations for the oscillatory shear. The NALD calculations of modulus at ultra-low frequencies match with experimental data, thus, opening a new paradigm in the field of polymer viscoelasticity research to bridge the timescale gap between experiments and theory.

[1] R. M. Elder, A. Zaccone, T. W. Sirk, ACS Macro Letters, 8(9), 1160 (2019) [2] T. W. Sirk, K. S. Khare, M. Karim, J. L. Lenhart, J. W. Andzelm, G. B. McKenna, R. Khare, Polymer 54(26), 7048 (2013)

Keywords: Cross-linked Epoxy; Oscillatory shear; Non-affine lattice dynamics; Molecular dynamics simulation; Glass transition

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