The aging rate of glasses has traditionally been modeled as a function of temperature, T, and fictive temperature, while density, ρ, is not explicitly included as a parameter. However, this description does not naturally connect to the modern understanding of what governs the relaxation rate in equilibrium. In equilibrium, it is well known that the relaxation rate, γeq, depends on temperature and density. In addition, a large class of systems obeys density scaling, which means the rate specifically depends on the scaling parameter, Γ = e(ρ)/T, where e(ρ) is a system specific function. This paper presents a generalization of the fictive temperature concept in terms of a fictive scaling parameter, Γfic, and a density scaling conjecture for aging glasses in which the aging rate depends on Γ and Γfic.

1.
J.
Dyre
, “
Colloquium: The glass transition and elastic models of glass-forming liquids
,”
Rev. Mod. Phys.
78
,
953
972
(
2006
).
2.
M. D.
Ediger
and
P.
Harrowell
, “
Perspective: Supercooled liquids and glasses
,”
J. Chem. Phys.
137
(
8
),
080901
(
2012
).
3.
L.
Berthier
and
G.
Biroli
, “
Theoretical perspective on the glass transition and amorphous materials
,”
Rev. Mod. Phys.
83
,
587
645
(
2011
).
4.
K.
Niss
and
T.
Hecksher
, “
Perspective: Searching for simplicity rather than universality in glass-forming liquids
,”
J. Chem. Phys.
149
(
23
),
230901
(
2018
).
5.
C.
Bauer
,
R.
Böhmer
,
S.
Moreno-Flores
,
R.
Richert
,
H.
Sillescu
, and
D.
Neher
, “
Capacitive scanning dilatometry and frequency-dependent thermal expansion of polymer films
,”
Phys. Rev. E
61
,
1755
1764
(
2000
).
6.
K.
Niss
,
D.
Gundermann
,
T.
Christensen
, and
J. C.
Dyre
, “
Dynamic thermal expansivity of liquids near the glass transition
,”
Phys. Rev. E
85
,
041501
(
2012
).
7.
N. O.
Birge
and
S. R.
Nagel
, “
Specific-heat spectroscopy of the glass transition
,”
Phys. Rev. Lett.
54
,
2674
2677
(
1985
).
8.
L. A.
Roed
,
D.
Gundermann
,
J. C.
Dyre
, and
K.
Niss
, “
Communication: Two measures of isochronal superposition
,”
J. Chem. Phys.
139
,
101101
(
2013
).
9.
A. Q.
Tool
and
C. G.
Eicitlin
, “
Variations caused in the heating curves of glass by heat treatment
,”
J. Am. Ceram. Soc.
14
,
276
308
(
1931
).
10.
O. S.
Narayanaswamy
, “
A model of structural relaxation in glass
,”
J. Am. Ceram. Soc.
54
,
491
(
1971
).
11.
G. W.
Schere
,
Relaxation in Glass and Composites
(
Wiley, New York
,
1986
).
12.
C. T.
Moynihan
,
A. J.
Easteal
,
M. A.
DeBolt
, and
J.
Tucker
, “
Dependence of the fictive temperature of glass on cooling rate
,”
J. Am. Ceram. Soc.
59
,
12
16
(
1976
).
13.
G. B.
McKenna
, “
Looking at the glass transition: Challenges of extreme time scales and other interesting problems
,”
Rubber Chem. Technol.
93
,
79
(
2020
).
14.
T.
Hecksher
,
N. B.
Olsen
, and
J. C.
Dyre
, “
Communication: Direct tests of single-parameter aging
,”
J. Chem. Phys.
142
,
241103
(
2015
).
15.
K.
Niss
, “
Mapping isobaric aging onto the equilibrium phase diagram
,”
Phys. Rev. Lett.
119
,
115703
(
2017
).
16.
B.
Riechers
,
L. A.
Roed
,
S.
Mehri
,
T. S.
Ingebrigtsen
,
T.
Hechsker
,
J. C.
Dyre
, and
K.
Niss
, “
Predicting nonlinear physical aging of glasses from equilibrium relaxation via the material time
,”
Sci. Adv.
8
,
eabl9809
(
2022
).
17.
D.
Cangialosi
,
V. M.
Boucher
,
A.
Alegría
, and
J.
Colmenero
, “
Physical aging in polymers and polymer nanocomposites: Recent results and open questions
,”
Soft Matter
9
,
8619
8630
(
2013
).
18.
X.
Monnier
,
D.
Cangialosi
,
B.
Ruta
,
R.
Busch
, and
I.
Gallino
, “
Vitrification decoupling from α-relaxation in a metallic glass
,”
Sci. Adv.
6
(
17
),
eaay1454
(
2020
).
19.
X.
Monnier
,
S.
Marina
,
X.
Lopez de Pariza
,
H.
Sardón
,
J.
Martin
, and
D.
Cangialosi
, “
Physical aging behavior of a glassy polyether
,”
Polymers
13
(
6
),
954
(
2021
).
20.
S. F.
Swallen
,
K. L.
Kearns
,
M. K.
Mapes
,
Y. S.
Kim
,
R. J.
McMahon
,
M. D.
Ediger
,
T.
Wu
,
L.
Yu
, and
S.
Satija
, “
Organic glasses with exceptional thermodynamic and kinetic stability
,”
Science
315
,
353
356
(
2007
).
21.
M. D.
Ediger
, “
Perspective: Highly stable vapor-deposited glasses
,”
J. Chem. Phys.
147
(
21
),
210901
(
2017
).
22.
C. M.
Roland
,
R.
Casalini
, and
M.
Paluch
, “
Isochronal temperature–pressure superpositioning of the α-relaxation in type-A glass formers
,”
Chem. Phys. Lett.
367
(
3
),
259
264
(
2003
).
23.
S.
Hensel-Bielowka
,
S.
Pawlus
,
C. M.
Roland
,
J.
Zioło
, and
M.
Paluch
, “
Effect of large hydrostatic pressure on the dielectric loss spectrum of type-A glass formers
,”
Phys. Rev. E
69
,
050501
(
2004
).
24.
K. L.
Ngai
,
R.
Casalini
,
S.
Capaccioli
,
M.
Paluch
, and
C. M.
Roland
, “
Do theories of the glass transition, in which the structural relaxation time does not define the dispersion of the structural relaxation, need revision?
,”
J. Phys. Chem. B
109
,
17356
17360
(
2005
).
25.
K.
Grzybowska
,
S.
Pawlus
,
M.
Mierzwa
,
M.
Paluch
, and
K. L.
Ngai
, “
Changes of relaxation dynamics of a hydrogen-bonded glass former after removal of the hydrogen bonds
,”
J. Chem. Phys.
125
,
144507
(
2006
).
26.
K.
Niss
,
C.
Dalle-Ferrier
,
G.
Tarjus
, and
C.
Alba-Simionesco
, “
On the correlation between fragility and stretching in glass-forming liquids
,”
J. Phys.: Condens. Matter
19
,
076102
(
2007
).
27.
A. I.
Nielsen
,
S.
Pawlus
,
M.
Paluch
, and
J. C.
Dyre
, “
Pressure dependence of the dielectric loss minimum slope for ten molecular liquids
,”
Philos. Mag.
88
(
33–35
),
4101
4108
(
2008
).
28.
K.
Adrjanowicz
,
J.
Pionteck
, and
M.
Paluch
, “
Isochronal superposition and density scaling of the intermolecular dynamics in glass-forming liquids with varying hydrogen bonding propensity
,”
RSC Adv.
6
,
49370
49375
(
2016
).
29.
H. W.
Hansen
,
A.
Sanz
,
K.
Adrjanowicz
,
B.
Frick
, and
K.
Niss
, “
Evidence of a one-dimensional thermodynamic phase diagram for simple glass-formers
,”
Nat. Commun.
9
,
518
(
2018
).
30.
C.
Alba-Simionesco
,
D.
Kivelson
, and
G.
Tarjus
, “
Temperature, density, and pressure dependence of relaxation times in supercooled liquids
,”
J. Chem. Phys.
116
,
5033
5038
(
2002
).
31.
C. M.
Roland
,
S.
Hensel-Bielowka
,
M.
Paluch
, and
R.
Casalini
, “
Supercooled dynamics of glass-forming liquids and polymers under hydrostatic pressure
,”
Rep. Prog. Phys.
68
,
1405
1478
(
2005
).
32.
T. B.
Schrøder
,
U. R.
Pedersen
,
N. P.
Bailey
,
S.
Toxvaerd
, and
J. C.
Dyre
, “
Hidden scale invariance in molecular van der Waals liquids: A simulation study
,”
Phys. Rev. E
80
,
041502
(
2009
).
33.
N.
Gnan
,
T. B.
Schrøder
,
U. R.
Pedersen
,
N. P.
Bailey
, and
J. C.
Dyre
, “
Pressure-energy correlations in liquids. IV. “Isomorphs” in liquid phase diagrams
,”
J. Chem. Phys.
131
(
23
),
234504
(
2009
).
34.
J. C.
Dyre
, “
Hidden scale invariance in condensed matter
,”
J. Phys. Chem. B
118
(
34
),
10007
10024
(
2014
).
35.
D.
Gundermann
,
U. R.
Pedersen
,
T.
Hecksher
,
N. P.
Bailey
,
B.
Jakobsen
,
T.
Christensen
,
N. B.
Olsen
,
T. B.
Schrøder
,
D.
Fragiadakis
,
R.
Casalini
,
C.
Michael Roland
,
J. C.
Dyre
, and
K.
Niss
, “
Predicting the density-scaling exponent of a glass-forming liquid from Prigogine–Defay ratio measurements
,”
Nat. Phys.
7
,
816
821
(
2011
).
36.
M.
Goldstein
, “
Viscous liquids and the glass transition: A potential energy barrier picture
,”
J. Chem. Phys.
51
,
3728
(
1969
).
37.
L. F.
Cugliandolo
,
J.
Kurchan
, and
L.
Peliti
, “
Energy flow, partial equilibration, and effective temperatures in systems with slow dynamics
,”
Phys. Rev. E
55
,
3898
3914
(
1997
).
38.
J.
Kurchan
, “
In and out of equilibrium
,”
Nature
433
(
7023
),
222
225
(
2005
).
39.
R.
Di Leonardo
,
L.
Angelani
,
G.
Parisi
, and
G.
Ruocco
, “
Off-equilibrium effective temperature in monatomic Lennard-Jones glass
,”
Phys. Rev. Lett.
84
,
6054
6057
(
2000
).
40.
N.
Gnan
,
C.
Maggi
,
T. B.
Schrøder
, and
J. C.
Dyre
, “
Predicting the effective temperature of a glass
,”
Phys. Rev. Lett.
104
,
125902
(
2010
).
41.
J. C.
Dyre
, “
Isomorph theory of physical aging
,”
J. Chem. Phys.
148
(
15
),
154502
(
2018
).
42.
J. C.
Dyre
, “
Isomorph theory beyond thermal equilibrium
,”
J. Chem. Phys.
153
(
13
),
134502
(
2020
).
43.
C. M.
Roland
,
S.
Bair
, and
R.
Casalini
, “
Thermodynamic scaling of the viscosity of van der Waals, H-bonded, and ionic liquids
,”
J. Chem. Phys.
125
(
12
),
124508
(
2006
).
44.
Z.
Wojnarowska
,
M.
Paluch
,
A.
Grzybowski
,
K.
Adrjanowicz
,
K.
Grzybowska
,
K.
Kaminski
,
P.
Wlodarczyk
, and
J.
Pionteck
, “
Study of molecular dynamics of pharmaceutically important protic ionic liquid-verapamil hydrochloride. I. Test of thermodynamic scaling
,”
J. Chem. Phys.
131
(
10
),
104505
(
2009
).
45.
H. W.
Hansen
,
B.
Frick
,
S.
Capaccioli
,
A.
Sanz
, and
K.
Niss
, “
Isochronal superposition and density scaling of the α-relaxation from pico- to millisecond
,”
J. Chem. Phys.
149
(
21
),
214503
(
2018
).
46.
H. W.
Hansen
,
F.
Lundin
,
K.
Adrjanowicz
,
B.
Frick
,
A.
Matic
, and
K.
Niss
, “
Density scaling of structure and dynamics of an ionic liquid
,”
Phys. Chem. Chem. Phys.
22
,
14169
(
2020
).
47.
Though e(ρ) is generally monotonically increasing exotic systems exist where this is not the case, for example, the Gaussian core model.
You do not currently have access to this content.