Lavergne François A, Sollich Peter, Trappe Véronique
Department of Physics, University of Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland.
Institute for Theoretical Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
J Chem Phys. 2022 Apr 21;156(15):154901. doi: 10.1063/5.0085773.
We show that the slow viscoelastic response of a foam is that of a power-law fluid with a terminal relaxation. Investigations of the foam mechanics in creep and recovery tests reveal that the power-law contribution is fully reversible, indicative of a delayed elastic response. We demonstrate how this contribution fully accounts for the non-Maxwellian features observed in all tests, probing the linear mechanical response function. The associated power-law spectrum is consistent with soft glassy rheology of systems with mechanical noise temperatures just above the glass transition [Fielding et al., J. Rheol. 44, 323 (2000)] and originates from a combination of superdiffusive bubble dynamics and stress diffusion, as recently evidenced in simulations of coarsening foam [Hwang et al., Nat. Mater. 15, 1031 (2016)].
我们表明，泡沫的缓慢粘弹性响应是具有终端松弛的幂律流体的响应。在蠕变和恢复测试中对泡沫力学的研究表明，幂律贡献是完全可逆的，这表明存在延迟弹性响应。我们展示了这种贡献如何完全解释在所有测试中观察到的非麦克斯韦特征，这些测试探测了线性机械响应函数。相关的幂律谱与机械噪声温度略高于玻璃化转变温度的系统的软玻璃态流变学一致[菲尔丁等人，《流变学杂志》44，323（2000）]，并且源于超扩散气泡动力学和应力扩散的组合，这一点最近在粗化泡沫的模拟中得到了证实[黄等人，《自然材料》15，1031（2016）]。
