Dependence of the glass transition temperature on heating and cooling rate

1974 ◽  
Vol 78 (26) ◽  
pp. 2673-2677 ◽  
Author(s):  
Cornelius T. Moynihan ◽  
Allan J. Easteal ◽  
James Wilder ◽  
Joseph Tucker
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Heating And Cooling

Development of Young's modulus of natural illitic clay during the heating and cooling stages of firing

Clay Minerals ◽  
2019 ◽  
Vol 54 (3) ◽  
pp. 229-233 ◽  
Author(s):  
Tomáš Húlan ◽  
Igor Štubňa ◽  
Andrei Shishkin ◽  
Jurijs Ozolins ◽  
Štefan Csáki ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Bound Water ◽  
Thermomechanical Analysis ◽  
X Ray Diffraction ◽  
Heating And Cooling ◽  
Thermal Expansion Coefficients

AbstractIllitic clay from the locality of Liepa, Latvia, was investigated using dynamic thermomechanical analysis during the heating and cooling stages of firing. Differential thermal analysis, thermogravimetry, thermodilatometry, X-ray diffraction and porosimetry were also performed to shed light on the processes influencing the elastic properties of clay. The increase in the Young's modulus (YM) at low temperatures was linked to the release of physically bound water. Above 850°C, the bulk density and YM both increased as a consequence of sintering. The YM was more sensitive to the progress of sintering compared to dimension changes. The YM values continued to increase during cooling until the glass-transition temperature was reached. At this temperature, the first microcracks caused by the differences in thermal expansion coefficients of the present phases were expected to appear. The YM showed a sharp V-shaped minimum at the β → α transition of quartz, which was a result of alternation of the mechanical radial stresses around the quartz grains. When the transition of quartz was completed, the YM continued to decrease because microcracks were still being created at the boundaries between the different phases. The decrease of the YM during cooling from the glass-transition temperature down to room temperature was ~50% for all of the firing temperatures and isothermal periods applied.

scholarly journals Oбобщенный кинетический критерий перехода жидкость--стекло

2020 ◽  
Vol 62 (10) ◽  
pp. 1706
Author(s):  
Д.С. Сандитов ◽  
В.В. Мантатов ◽  
С.Ш. Сангадиев
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Glassy State ◽  
Fluctuation Volume ◽  
Dimensionless Constant ◽  
Transition Criterion

Using the model of delocalized atoms, a substantiation and generalization of the Schmelzer glass transition criterion is proposed. In contrast to the Bartenev and Volkenstein - Ptitsyn approaches, in the generalized kinetic glass transition criterion, along with the relaxation time and the cooling rate of the melt, the glass transition temperature and an almost universal dimensionless constant appear, which is determined by the fraction of the fluctuation volume frozen at the glass transition temperature. The idea is developed that the liquid goes into a glassy state when its cooling rate q reaches a certain fraction of C_g of the characteristic cooling rate q_g=(T_g/taug), which is closely related to the relaxation time of the structure tau_g at the glass transition temperature T_g.

scholarly journals Fractographic analysis of lithium silicate crown failures during sintering

2019 ◽  
Vol 7 ◽  
pp. 2050313X1983896
Author(s):  
Ulrich Lohbauer ◽  
Michael Wendler ◽  
Doreen Rapp ◽  
Renan Belli
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Computer Aided Design ◽  
Thermal Stresses ◽  
Point Contact ◽  
Lithium Silicate ◽  
Contact Points ◽  
Computer Aided

The two-step production process of glass-ceramic dental restorations involves a computer-aided design/computer-aided machining step followed by a crystallization firing for the final material properties to be achieved. Certain firing parameters are believed to trigger spontaneous fracture of crowns during the cooling process. In this study, cooling fractures have been reproducibly observed and investigated using fractography combined with material (glass transition temperature) and process (cooling rate) characterization. Stress distribution was visualized using birefringence measurements. Fractographic observations revealed fracture starting at the intaglio side of the crowns specifically at contact points with the support firing pins. Further analysis showed that a fast cooling rate was applied during the glass transition region. Thermal stresses were concentrated around the firing pin supports and released the fracture. To prevent such fractures, a slow cooling protocol below the glass transition temperature is our recommendation to dental technicians. Furthermore, the use of planar firing pad or paste supports is advised over the use of point contact supports.

scholarly journals 26. Invariance of the glass transition temperature of plant vitrification solutions with cooling rate

Cryobiology ◽  
2012 ◽  
Vol 65 (3) ◽  
pp. 347 ◽  
Author(s):  
Aline Schneider Teixeira ◽  
Miloš Faltus ◽  
Jiřı´ Zámečnı´k ◽  
Renata Kotková ◽  
Maria Elena González-Benito ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate

Influence of Cooling Rate on Glass Transition Temperature of Sucrose Solutions and Rice Starch Gel

2003 ◽  
Vol 68 (6) ◽  
pp. 1970-1975 ◽  
Author(s):  
C.-L. Hsu ◽  
D.R. Heldman ◽  
T.A. Taylor ◽  
H.L. Kramer
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Rice Starch ◽  
Sucrose Solutions ◽  
Starch Gel

A Rapid Heating and Cooling Rate Dilatometer for Measuring Thermal Expansion in Dental Porcelain

1989 ◽  
Vol 68 (9) ◽  
pp. 1316-1318 ◽  
Author(s):  
S.W. Twiggs ◽  
J.R. Searle ◽  
R.D. Ringle ◽  
C.W. Fairhurst
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Rapid Heating ◽  
Optical Pyrometer ◽  
Thermal Expansion Data ◽  
Dental Porcelain ◽  
Temperature Range ◽  
Heating And Cooling

Herein we describe a dilatometer that consists of a low-mass infrared furnace for rapid heating or cooling, an optical pyrometer, and a laser interferometer. The dilatometer facilitates observations of thermal expansion at rates comparable with those in dental laboratory practice over the temperature range necessary for comparison of thermal expansion of dental porcelain and alloy. Examples of thermal expansion data obtained at a 600°Clmin heating rate on NIST SRM 710 glass and dental porcelain are reported. To a limited extent, thermal expansion data above the glass-transition temperature range of dental porcelain were obtained. A shift of the glass-transition temperature range to higher temperatures was observed for both materials, compared with data obtained at 20°Clmin.

Cooling rate dependence of the glass transition temperature of polymer melts: Molecular dynamics study

2002 ◽  
Vol 117 (15) ◽  
pp. 7364-7372 ◽  
Author(s):  
Joachim Buchholz ◽  
Wolfgang Paul ◽  
Fathollah Varnik ◽  
Kurt Binder
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Polymer Melts ◽  
Rate Dependence

Glass-transition temperature and cooling rate of glass-forming melts

2016 ◽  
Vol 58 (10) ◽  
pp. 2078-2080 ◽  
Author(s):  
D. S. Sanditov ◽  
S. Sh. Sangadiev ◽  
M. V. Darmaev
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Glass Forming

Thermal Relaxations of Polymers Revealed by Reversing and Non-Reversing Coefficient of Thermal Expansion

2010 ◽  
Vol 123-125 ◽  
pp. 451-454
Author(s):  
Robert A. Shanks
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Expansion Coefficient ◽  
Structural Changes ◽  
Coefficient Of Thermal Expansion ◽  
Modulated Temperature ◽  
Heating And Cooling ◽  
Modulated Temperature Dsc

Reversible and irreversible events can be resolved) using modulated temperature DSC and TMA. Each technique has advantages, those for TMA include longer times and slower scan rates that allow greater approach to material equilibrium. The thermal expansion coefficient and glass transition temperature can be isolated from relaxations and structural changes. Modulated temperature thermomechanometry (mT-TM) is used to characterize amorphous thermoplastics including PS, PMMA, PC and PPO, and the results including annealing, heating and cooling.

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