Crossover of aging dynamics in polymer glass: from cumulative aging to non-cumulative aging

Structural relaxation, dynamical arrest and aging in soft-sphere liquids

We investigate the structural relaxation of a soft-sphere liquid quenched isochorically ($ϕ=0.7$) and instantaneously to different temperatures $T_f$ above and below the glass transition. For this, we combine extensive Brownian dynamics simulations and theoretical calculations based on the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory. The response of the liquid to a quench generally consists of a sub-linear increase of the $α$-relaxation time with system's age. Approaching the ideal glass-transition temperature from above ($T_f>T^a$) sub-aging appears as a tr…

通过化学无序老化调控多组分金属玻璃的脆性

Tuning brittleness in multi-component metallic glasses through chemical disorder aging

通过混合MC-MD模拟研究多组分金属玻璃老化对剪切弹性-塑性转变的影响，揭示老化诱导的二十面体有序化与剪切转变区协同形成的内在关联，并量化了老化时间依赖的塑性重排敏感性及空间关联长度的增长。

Phase separation and aging dynamics of binary liquid in porous media

We employ the state-of-the-art molecular dynamics simulations to study the kinetics of phase separation and aging phenomena of segregating binary fluid mixtures imbibed in porous materials. Different random porous structures are considered to understand the effect of pore morphology on coarsening dynamics. We find the effect of complex geometrical confinement resulting in the dramatic slowing down in the phase separation dynamics. The domain growth follows the power law with an exponent dependent on the porous host structure. After the transient period, a crossover to a slower domain growth is…

Spin-glass--like aging in colloidal and granular glasses

Motivated by the mean field prediction of a Gardner phase transition between a "normal glass" and a "marginally stable glass", we investigate the off-equilibrium dynamics of three-dimensional polydisperse hard spheres, used as a model for colloidal or granular glasses. Deep inside the glass phase, we find that a sharp crossover pressure $P_{\rm G}$ separates two distinct dynamical regimes. For pressure $P < P_{\rm G}$, the glass behaves as a normal solid, displaying fast dynamics that quickly equilibrates within the glass free energy basin. For $P>P_{\rm G}$, instead, the dynamics becomes stro…

Atomic-scale relaxation dynamics and aging in a metallic glass probed by X-ray photon correlation spectroscopy

We use X-Ray Photon Correlation Spectroscopy to investigate the structural relaxation process in a metallic glass on the atomic length scale. We report evidence for a dynamical crossover between the supercooled liquid phase and the metastable glassy state, suggesting different origins of the relaxation process across the transition. Furthermore, using different cooling rates we observe a complex hierarchy of dynamic processes characterized by distinct aging regimes. Strong analogies with the aging dynamics of soft glassy materials, such as gels and concentrated colloidal suspensions, point at …

自旋玻璃中老化与回春的相互作用

Interplay between aging and rejuvenation in spin glasses

本研究测量了Cu₀.₉₂Mn₀.₀₈单晶自旋玻璃的老化特性，对比淬火与有限冷却速率两种方案的老化曲线，揭示了老化与回春的相互作用对定量比较的影响，明确回春是两类生长速率差异的成因。

Two-step build-up of a thermoreversible polymer network: From early local to late collective dynamics

We probe the mechanisms at work in the build-up of thermoreversible gel networks, with the help of hybrid gelatin gels containing a controlled density of irreversible, covalent crosslinks (CL), which we quench below the physical gelation temperature. The detailed analysis of the dependence on covalent crosslink density of both the shear modulus and optical activity evolutions with time after quench enables us to identify two stages of the physical gelation process, separated by a temperature dependent crossover modulus: (i) an early nucleation regime during which rearrangements of the triple-h…

摩擦控制的颗粒材料中的重入老化与流化

Friction-controlled reentrant aging and fluidization in granular materials

本研究通过离散元模拟揭示摩擦在颗粒材料循环剪切压实中的双重作用，发现重入的非单调流化行为，并阐明其控制老化与流化的微观机制。

老化胶体粘土中玻璃-玻璃转变的流变学特征

Rheological signatures of a glass-glass transition in an aging colloidal clay

通过动态力学分析，发现老化胶体粘土在约三天时发生玻璃-玻璃转变，流变参数突变且与弛豫时间偏离一致，证实了该转变的存在。

Sound attenuation in finite-temperature stable glasses

The temperature dependence of the thermal conductivity of amorphous solids is markedly different from that of their crystalline counterparts, but exhibits universal behaviour. Sound attenuation is believed to be related to this universal behaviour. Recent computer simulations demonstrated that in the harmonic approximation sound attenuation $Γ$ obeys quartic, Rayleigh scattering scaling for small wavevectors $k$ and quadratic scaling for wavevectors above the Ioffe-Regel limit. However, simulations and experiments do not provide a clear picture of what to expect at finite temperatures where an…

Dynamics of a colloidal glass during stress-mediated structural arrest

We employ parallel superposition rheology to study the dynamics of an aging colloidal glass in the presence of a mean field stress. Over a range of intermediate stresses, the loss modulus exceeds the storage modulus at short times but develops a maximum concomitant with a crossover between the two as the system ages. This is attended by a narrowing of the loss peak on increasing stress. We show that this feature is characteristic of the structural arrest in these materials, which is made observable on reasonable timescales by the activating influence of the stress. The arrest time displays an …