Aging dynamics

Figure 4.121. Polyimides examples of creep modulus (GPa) versus time (h) at 100°C and 300°C 4.26.5 Ageing Dynamic fatigue...

In the next sections I briefly discuss some of the theoretical concepts important to understanding the glass state and nonequilibrium aging dynamics. 

P. Mayer, S. Leonard, L. Berthier, J. P. Garrahan, and P. Sollich, Activated aging dynamics and negative fluctuation-dissipation ratios. Phys. Rev. Lett. 96, 030602 (2006). 

A. Crisanti and F. Ritort, Equilibrium and ageing dynamics of simple models for glasses. J. Phys. (Condensed Matter) 12, 6413-6422 (2000). 

Fig. 22 Steady state incoherent intermediate scattering functions (z) measured in the vorticity direction as functions of accumulated strain jf for various shear rates y data from molecular dynamics simulations of a supercooled binary Lenard-Jones mixture below the glass transition ate taken from [91]. These collapse onto a yield scaling function at long times. The wavevector is q = 3.55/R (at the peak of Sq). The quiescent curve, shifted to agree with that at the highest y, shows ageing dynamics at longer times outside the plotted window. The apparent yielding master function from simulation is compared to those calculated in ISHSM for glassy states at or close to the transition (separation parameters s as labeled) and at nearby wave vectors (as labeled). ISHSM curves were chosen to match the plateau value fq, while strain parameters yc = 0.083 at = 0 solid line) and y, = 0.116 at e = 10 dashed line) were used from [45]...

Heterogeneous and Aging Dynamics in Single and Stacked Thin Polymer Films... 

Keywords Aging dynamics Glass transition Heterogeneous dynamics Interfacial interaction Memory and rejuvenation effects Stacked thin polymer films... 

Measurements of Aging Dynamics in Thin Polymer Films. 75... 

Remarks on Anomaly Observed in Aging Dynamics in Ultrathin P2CS Films 101... 

Here, we would like to show our recent results on the glass transition dynamics of stacked thin polymer films and the aging dynamics of ultrathin polymer films, as investigated by DSC and DRS. For both cases, heterogeneous dynamics such as the... 

Dielectric measurements were carried out in the same experimental setup described in Sect. 2.2 for the ultrathin films of P2CS with thickness d of 3.7,5.4,9.0,9.5, and 22 nm, in order to investigate the aging dynamics below Tg. The complex dielectric constant (= e — is") was evaluated as a function of temperature T, aging time fw, and the frequency of applied electric field/. The value of was obtained from the value of the complex electrical capacitance of the sample condenser C (= C — iC ), on the assumption that C = Cq is valid, where Cq is the geometrical capacitance of the sample condenser. 

For investigation of the aging dynamics, the following two temperature protocols were employed ... 

As discussed, the aging dynamics of ultrathin P2CS films are quite different from those of thicker films, and have an anomalous dependence on the thickness and temperature. Here, the microscopic origin for such an anomaly is discussed on the basis of segmental dynamics measurements using DRS. 

Here, we return to the aging dynamics observed for isothermal aging at Ta. For a given frequency/, we could observe the change in T ) from c"f(= a"... 

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