Physical Aging, the Local Dynamics of Glass-Forming Polymers under Nanoscale Confinement

2014 ◽  
Vol 118 (30) ◽  
pp. 9096-9103 ◽  
Author(s):  
Amit Shavit ◽  
Robert A. Riggleman
Keyword(s):  
Physical Aging ◽  
Local Dynamics ◽  
Glass Forming

scholarly journals Physical Aging Behavior of a Glassy Polyether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 954
Author(s):  
Xavier Monnier ◽  
Sara Marina ◽  
Xabier Lopez de Pariza ◽  
Haritz Sardón ◽  
Jaime Martin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Glassy State ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Narrow Temperature Range ◽  
Glass Forming ◽  
Fast Scanning Calorimetry

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

scholarly journals Evolution of collective motion in a model glass-forming liquid during physical aging

2013 ◽  
Vol 138 (12) ◽  
pp. 12A528 ◽  
Author(s):  
Amit Shavit ◽  
Jack F. Douglas ◽  
Robert A. Riggleman
Keyword(s):  
Physical Aging ◽  
Collective Motion ◽  
Glass Forming ◽  
Model Glass

The Enthalpic Relaxation of Amorphous Poly(Aryl Ether Ketone)s

1997 ◽  
Vol 9 (1) ◽  
pp. 1-15 ◽  
Author(s):  
A A Goodwin ◽  
M M Browne
Keyword(s):  
Physical Aging ◽  
Aryl Ether ◽  
Forming Process ◽  
Scanning Calorimetry ◽  
Substitution Pattern ◽  
Glass Forming ◽  
Aryl Ether Ketone ◽  
Ether Ketone ◽  
Composite Curve ◽  
Kinetics Of

The development of physical aging in four amorphous poly(aryl ether ketone)s at temperatures below the glass transition temperature, Tg, was studied using differential scanning calorimetry (DSC). The change in enthalpy lost on aging, determined by scanning through Tg, was used to determine the kinetics of the aging process through fitting to the Cowie–Ferguson model. The kinetics of aging were found to depend on the ketone–ether ratio as well as the substitution pattern of the polymers. The maximum enthalpy lost at equilibrium, Δ H∞, was found to be a linear function of the change in heat capacity at Tg, Δ Cp(Tg), and the degree of supercooling, Δ T. A composite curve incorporating Tg values from physical aging and dynamic mechanical studies, covering 15 decades, could be fitted to the Volger–Fulcher equation and demonstrated that physical aging is an extension of the glass forming process.

scholarly journals Fast contribution to the activation energy of a glass-forming liquid

2019 ◽  
Vol 116 (34) ◽  
pp. 16736-16741 ◽  
Author(s):  
Tina Hecksher ◽  
Niels Boye Olsen ◽  
Jeppe C. Dyre
Keyword(s):  
Activation Energy ◽  
High Frequency ◽  
Physical Aging ◽  
Temperature Jump ◽  
Silicone Oil ◽  
Relative Magnitude ◽  
Glass Forming ◽  
Temperature Jumps ◽  
Fast Change ◽  
Time Formalism

This paper presents physical-aging data for the silicone oil tetramethyl-tetraphenyl trisiloxane. The density and the high-frequency plateau shear modulus G∞ were monitored following temperature jumps starting from fully equilibrated conditions. Both quantities exhibit a fast change immediately after a temperature jump. Adopting the material-time formalism of Narayanaswamy, we determine from the dielectric loss at 0.178 Hz the time evolution of the aging-rate activation energy. The relative magnitude of the fast change of the activation energy differs from that of the density, but is identical to that of G∞. In fact, the activation energy is proportional to G∞ throughout the aging process, with minor deviations at the shortest times. This shows that for the silicone oil in question the dynamics are determined by G∞ in—as well as out of—equilibrium.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

The effect of an aluminum heat-sink layer on the laser-induced amorphization of SiOx/TeGeSn/SiOx phase-change recording films

1989 ◽  
Vol 47 ◽  
pp. 574-575
Author(s):  
Matthew R. Libera ◽  
Martin Chen
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Heat Sink ◽  
Multilayer Film ◽  
Glassy Phase ◽  
Film Structure ◽  
Glass Forming ◽  
Active Storage ◽  
Dielectric Layers ◽  
Amorphous States

Phase-change erasable optical storage is based on the ability to switch a micron-sized region of a thin film between the crystalline and amorphous states using a diffraction-limited laser as a heat source. A bit of information can be represented as an amorphous spot on a crystalline background, and the two states can be optically identified by their different reflectivities. In a typical multilayer thin-film structure the active (storage) layer is sandwiched between one or more dielectric layers. The dielectric layers provide physical containment and act as a heat sink. A viable phase-change medium must be able to quench to the glassy phase after melting, and this requires proper tailoring of the thermal properties of the multilayer film. The present research studies one particular multilayer structure and shows the effect of an additional aluminum layer on the glass-forming ability.

Crystallization in Al 88 RE 8 Ni 4 glass-forming alloys

2002 ◽  
Vol 82 (12) ◽  
pp. 2483-2497 ◽  
Author(s):  
T. K. Croat ◽  
A. K. Gangopadhyay ◽  
K. F. K Elton
Keyword(s):  
Glass Forming
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