Some comments on heterogeneity at the glass transition

Sillescu, H.

doi:10.1088/0953-8984/11/10a/024

Cited by 8 publications

(5 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…45,46 Although our experiment, based on its small contact size and experimentally applicable velocities, should be insensitive to such long-range density fluctuations, the ultraslow process can couple to the ␣ relaxation, leading to apparent nonergodic time-averaged correlations occurring on the time scale of the ␣ relaxation. 45 Finally, it should be noted that in many experiments, the structural relaxation time is comparable to the ␣-relaxation time ␣ for 1 msϽ ␣ Ͻ 100 ms. 47 This time regime is applicable to most of the data discussed in Fig. 4 except for the two divergent points at T = 377 and 380 K, with relaxation times of 3700 and 430 ms, respectively.…”

Section: Fig 3 Friction-peak Intensity F Fmaxmentioning

confidence: 91%

Molecular dissipation phenomena of nanoscopic friction in the heterogeneous relaxation regime of a glass former

Sills

Gray

Overney

2005

The Journal of Chemical Physics

View full text Add to dashboard Cite

Nanoscale sliding friction involving a polystyrene melt near its glass transition temperature Tg (373 K) exhibited dissipation phenomena that provide insight into the underlying molecular relaxation processes. A dissipative length scale that shows significant parallelism with the size of cooperatively rearranging regions (CRRs) could be experimentally deduced from friction-velocity isotherms, combined with dielectric loss analysis. Upon cooling to approximately 10 K above Tg, the dissipation length Xd grew from a segmental scale of approximately 3 A to 2.1 nm, following a power-law relationship with the reduced temperature Xd approximately TR-phi. The resulting phi=1.89+/-0.08 is consistent with growth predictions for the length scale of CRRs in the heterogeneous regime of fragile glass formers. Deviations from the power-law behavior closer to Tg suggest that long-range processes, e.g., the normal mode or ultraslow Fischer modes, may couple with the alpha relaxation, leading to energy dissipation in domains of tens of nanometers.

show abstract

Section: Fig 3 Friction-peak Intensity F Fmaxmentioning

confidence: 91%

Molecular dissipation phenomena of nanoscopic friction in the heterogeneous relaxation regime of a glass former

Sills

Gray

Overney

2005

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Different kinds of static and dynamic heterogeneity at the glass transition, in relation to recent experiments, were discussed by Sillescu. 212 He states that during the last few years a number of experimental methods have been developed whereby a dynamically distinguishable sub-ensemble can be selected in a supercooled liquid close to T g and its return to the full equilibrium ensemble can be subsequently monitored. These experiments provide a pragmatic way of quantifying heterogeneity via the selection procedure.…”

Section: Ln[ Ln ( )] Lnmentioning

confidence: 99%

4 Dispersive kinetics

Płonka¹

2001

Annu. Rep. Prog. Chem., Sect. C

View full text Add to dashboard Cite

“…Behavior of a many glass-forming substances at temperatures near T g gives evidence for regions of different molecular mobility, that is, for heterogeneity. − The dynamical properties of the regions can vary with time. In this case, the heterogeneity is said to be dynamical.…”

Section: Introductionmentioning

confidence: 99%

Dynamical Heterogeneity in Glassy o-Terphenyl: Manifestation of Environment Changes in Photoisomerization Kinetics of Probe Molecules

Grebenkin

Большаков

2007

J. Phys. Chem. B

View full text Add to dashboard Cite

A new method for the investigation of dynamical heterogeneity in glassy matrixes is presented and illustrated by the example of o-terphenyl (OTP). UV-vis absorption spectroscopy has been used to monitor the cis-trans isomerization kinetics of probe molecules in glassy OTP. The dependence of isomerization quantum yield on light intensity has been established. This dependence is shown to be due to the change in the local environment of the probe molecules. The simple model is suggested to estimate the time required for the environment to change, tauex. The tauex values from 2.6 x 10(2) to 1.9 x 10(5) s have been obtained for environments of molecules of 1-naphthylazomethoxybenzene (NAMB) in OTP over a temperature range from 244 to 204 K (Tg+1 to Tg-39 K). The temperature dependence of exchange time has a non-Arrhenius character. As the temperature decreases, an increase in exchange time slows down. The activation energy of the relaxation process is 54 kJ/mol over the range of 224-239 K.

show abstract

Some comments on heterogeneity at the glass transition

Cited by 8 publications

References 33 publications

Molecular dissipation phenomena of nanoscopic friction in the heterogeneous relaxation regime of a glass former

Molecular dissipation phenomena of nanoscopic friction in the heterogeneous relaxation regime of a glass former

4 Dispersive kinetics

Dynamical Heterogeneity in Glassy o-Terphenyl: Manifestation of Environment Changes in Photoisomerization Kinetics of Probe Molecules

Contact Info

Product

Resources

About