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arXiv · 2608.07330

Segmental Dynamics in the Strain-hardening Regime for Poly(methyl methacrylate) Glasses with and without Melt-stretching

Enran Xing·Trevor Bennin·Masoud Razavi·M. D. Ediger
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Abstract

Strain-hardening is a feature of polymer glasses during large deformation, which helps to stabilize the glasses against breakage. Experimentally, little is known about the segmental dynamics during strain-hardening, and such data is important for building a molecular-level theory of polymer glasses deformed in this regime. Here, using a photobleaching technique, we measured the segmental dynamics of lightly-crosslinked poly(methyl methacrylate) (PMMA) glasses with and without melt-stretching, which were deformed into the strain-hardening regime with local engineering strain rates from 10^-4.6 s^-1 to 10^-4 s^-1 at Tg-23K and Tg-33K. We find that melt-stretched PMMA glasses show a more prominent strain-hardening feature and faster segmental dynamics by a factor of about 15% compared to PMMA without melt-stretching. At a given true strain rate, the segmental dynamics of PMMA without melt-stretching are accelerated in the deep strain-hardening regime from the value just beyond yield, by up to 40% at 0.8 true strain. Our observations are in agreement with previously published simulation results.

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Enran Xing, Trevor Bennin, Masoud Razavi, M. D. Ediger. 2026-08-07. Segmental Dynamics in the Strain-hardening Regime for Poly(methyl methacrylate) Glasses with and without Melt-stretching. https://doi.org/10.1021/acs.macromol.2c01442

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