scholarly journals Hydration enthalpies of amorphous sucrose, trehalose and maltodextrins and their relations to heat capacities

2021 ◽  
Author(s):  
Ekaterina Bogdanova ◽  
Anna Millqvist Fureby ◽  
Vitaly Kocherbitov
Keyword(s):  
Glass Transition ◽  
Heat Capacities ◽  
Glassy Matrix ◽  
Small Solute

The mechanisms of the glass transition and the behavior of small solute molecules in the glassy matrix is one of most important topics of modern thermodynamics. Water plays an important...

The influence of crystalline texture on the tensile properties of natural rubber. I

1974 ◽  
Vol 338 (1615) ◽  
pp. 459-478 ◽  
Keyword(s):  
Glass Transition ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Amorphous Phase ◽  
Crystalline Phase ◽  
Full Range ◽  
Glassy Matrix ◽  
Tensile Behaviour ◽  
Crystalline Morphology ◽  
Temperature Range

The crystalline morphologies that are attainable in samples of natural rubber (n. r.), by extending the samples prior to crystallization, are reviewed. Specimens covering the full range of crystalline morphologies possible have been prepared and tensile tested between – 120 and – 26 °C. The tensile behaviour of crystalline samples is compared and contrasted with that of oriented, but non-crystalline, identical natural rubber in the same temperature range. It is found that the tensile behaviour of semi-crystalline n. r. is dominated by the amorphous phase throughout the temperature range – 120 to – 26 °C. At temperatures above the glass transition temperature ( T g ) of the amorphous phase, the crystalline phase acts mainly as a diluent of the amorphous phase. At temperatures below T g , where the crystalline phase is set in a glassy matrix, it is found that the crystalline morphology does significantly affect the tensile behaviour. Attempts are made to differentiate the effects of crystallinity, crystalline morphology and orientation of the amorphous phase on the tensile properties of natural rubber.

The heat capacities of solid Ni-Zr alloys and their relationship to the glass transition

1991 ◽  
Vol 12 (5) ◽  
pp. 538-545 ◽  
Author(s):  
J.F Smith ◽  
Q Jiang ◽  
R Lück ◽  
B Predel
Keyword(s):  
Glass Transition ◽  
Heat Capacities ◽  
Zr Alloys

Luminescence différée d'une solution organique vitreuse photoactivée et transition vitreuse

1977 ◽  
Vol 55 (13) ◽  
pp. 2517-2522 ◽  
Author(s):  
D. Ceccaldi
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Kinetic Theory ◽  
Rise Time ◽  
Time Dependent ◽  
Glassy Matrix ◽  
Temperature Dependent

A general kinetic theory is used to explain the shapes of photoionized sample luminescence curves perturbed by thermal jumps (Δ ∼ 1 K, rise time ∼ 1 s). The samples studied are photoactivated organic vitreous solutions of TMPD/MCH 10−3 M and TMPD/3-MP 10−3 M. The experiments are performed within a temperature range (63–91 K) which includes the glass transition temperature Tg. It is shown that there is a slow diffusion of the trapped electrons towards the cation and competition between thermal detrapping and tunneling. The tunneling/thermal detrapping ratio Y is not time dependent during an isothermal luminescence and is only slowly temperature dependent if T ≤ Ty. Ty is very close to Tg. For T > Ty, Y decreases rapidly with T. The activation energy for thermal detrapping shows a maximum when the temperature reaches [Formula: see text] The glass transition temperature Tg may therefore be defined empirically as:[Formula: see text]Finally we obtain a glassy matrix relaxation time, τ, which decreases with T.

Heat Capacities of Isomeric 2-Butoxyethanols from 13 to 300 K: Fusion and Glass Transition

2000 ◽  
Vol 73 (9) ◽  
pp. 1987-1991 ◽  
Author(s):  
Tooru Atake ◽  
Hitoshi Kawaji ◽  
Takeo Tojo ◽  
Koji Kawasaki ◽  
Yasushiro Ootsuka ◽  
...  
Keyword(s):  
Glass Transition ◽  
Heat Capacities

scholarly journals Modeling of atmospheric freeze-drying for sliced fruit

2018 ◽  
Author(s):  
Kyuya Nakagawa ◽  
Akane Horie ◽  
Takashi Kobayashi
Keyword(s):  
Mathematical Model ◽  
Glass Transition ◽  
Vapor Pressure ◽  
Heat Balance ◽  
Freeze Drying ◽  
Glassy State ◽  
Glassy Matrix ◽  
Reasonable Accuracy ◽  
Balance Equations ◽  
Apple Slices

A mathematical model that simulates atmospheric freeze-drying for apple slices was developed based on the classical mass and heat balance equations. When operated above the glass transition temperature, product shrinkage and micro-collapse due to the glass-rubber transition occurred. So, instead of assuming formation of dried and frozen zones, a glassy matrix with particular vapor pressure was assumed. Apparent vapor pressure of apple slices in the glassy state was experimentally measured and summarized in a diagram, and the values in this diagram were employed for the simulation. This approach well predicted drying kinetics with reasonable accuracy with simplified equations. Keywords: atmospheric freeze-drying; food; mathematical model; glassy state 

GLASS FORMING ABILITY OF HARD MAGNETIC Nd55Al20Fe25 BULK GLASSY ALLOY WITH DISTINCT GLASS TRANSITION

2005 ◽  
Vol 19 (22) ◽  
pp. 3493-3500 ◽  
Author(s):  
L. XIA ◽  
C. L. JO ◽  
Y. D. DONG
Keyword(s):  
Glass Transition ◽  
Glassy Alloy ◽  
Bulk Sample ◽  
Glass Forming Ability ◽  
Glassy Matrix ◽  
Section Thickness ◽  
Xrd Pattern ◽  
Glass Forming ◽  
Bulk Glassy Alloy ◽  
Hard Magnetic Properties

Nd 55 Al 20 Fe 25 bulk sample was prepared in the shape of rods 3 mm in diameter by suction casting. The sample exhibits typical amorphous characters in XRD pattern, distinct glass transition in DSC traces and hard magnetic properties. The distinct glass transition, which is invisible in DSC traces of previously reported Nd — Al — Fe ternary BMGs, allows us to investigate the glass forming ability (GFA) of Nd 55 Al 20 Fe 25 alloy using the reduced glass transition temperature Trg and the recently defined parameter γ. However, it is found that the obtained diameter of the Nd 55 Al 20 Fe 25 glassy rod is much larger than the critical section thickness of the BMG predicted by either Trg or γ. The microstructure of Nd 55 Al 20 Fe 25 as-cast rod was studied and the apparent GFA of the alloy was supposed to be enhanced by the metastable nano-precipitates dispersed within the glassy matrix.

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