Application of TMA for Rapid Evaluation of Low-Temperature Properties of Elastomer Vulcanizates

1979 ◽  
Vol 52 (4) ◽  
pp. 735-747
Author(s):  
D. W. Brazier ◽  
G. H. Nickel
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Low Temperature ◽  
Linear Thermal Expansion ◽  
Dimensional Change ◽  
Rate Of Change ◽  
Transition Range ◽  
Free Expansion ◽  
Wide Range ◽  
Scan Rate

Abstract Static thermomechanical analysis has been investigated as a method for determining the low-temperature properties of vulcanizates. Dimensional changes of a sample in free expansion, indentation, or tension are monitored as the sample is heated at a known and reproducible rate. The first derivative of the dimensional change is simultaneously recorded. TMA/DTMA data obtained in free expansion gives the linear thermal expansion coefficient at any temperature during the experiment. The glass transition is observed as a change in slope as in dilatometric determinations. In the indentation mode, the thermogram is the result of competition between thermal expansion and indentation. For tension measurements, the thermogram records the additive sum of thermal expansion and tensional strain development. For indentation and tension, the glass transition is obtained by a standard extrapolation method. A maximum in the DTMA thermogram is also observed which represents the maximum rate of change as the sample is heated through the glass transition range. The temperature of this maximum, Tgd, is characteristic of a vulcanizate. Variation in scan rate between 2 and 20°C/min has little effect on Tgo and no effect on Tgd. At 50°C/min, thermal gradient effects predominate. For a wide range of vulcanizates in tension or indentation, Tgo or Tgd versus the Gehman rigidity modulus gives a linear relationship. Exact temperature agreement is not observed because of differences in the experimental techniques. In blends, several Tgd values are observed. Plasticizer effects can either be observed by a shift in the Tgo or by a change in the thermogram profile, the extent of indentation and temperature range over which it occurs. The extent of indentation correlates with vulcanizate hardness as expected. The indentation of a rubber sample by a flat probe has been treated mathematically in the literature, and the determination of Young's modulus by TMA/DTMA is now being investigated. In conclusion, the ease of sample preparation and the rapidity of TMA/DTMA measurements offers a quick approach to assessing the low-temperature properties of vulcanizates. At 20°C/min scan rate, runs can be completed in as little as four minutes (80°C total scan) if the sample has a single transition.

Investigation of CaSO4-KPO3-Na2B4O7 System as a Basis for Synthesis of Low-Melting Glasses Used as a Glass-Solder Material

2020 ◽  
Vol 989 ◽  
pp. 265-269 ◽  
Author(s):  
Alexey V. Stolbovsky ◽  
Svetlana Murzinova ◽  
Vita Vyatchina
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Softening Temperature ◽  
Glass Formation Region ◽  
Formation Region ◽  
Solder Material ◽  
Concentration Dependences

The possibility of using the compositions of CaSO4-KPO3-Na2B4O7 system as a glass-solder material is shown. A glass formation region has been established in ternary system. The concentration dependences of linear thermal expansion coefficient, the softening temperature and the glass transition temperature are determined and discussed.

scholarly journals Thermophysical and anion diffusion properties of (U x ,Th 1− x )O 2

2014 ◽  
Vol 470 (2171) ◽  
pp. 20140427 ◽  
Author(s):  
Michael W. D. Cooper ◽  
Samuel T. Murphy ◽  
Paul C. M. Fossati ◽  
Michael J. D. Rushton ◽  
Robin W. Grimes
Keyword(s):  
Thermal Expansion ◽  
Specific Heat ◽  
Solid Solutions ◽  
Defect Formation ◽  
Linear Thermal Expansion ◽  
Lattice Parameter ◽  
Thermal Dependence ◽  
Vegard’S Law ◽  
Wide Range ◽  
Superionic Transition

Using molecular dynamics, the thermophysical properties of the (U x ,Th 1− x )O 2 system have been investigated between 300 and 3600 K. The thermal dependence of lattice parameter, linear thermal expansion coefficient, enthalpy and specific heat at constant pressure is explained in terms of defect formation and diffusivity on the oxygen sublattice. Vegard's law is approximately observed for solid solution thermal expansion below 2000 K. Different deviations from Vegard's law above this temperature occur owing to the different temperatures at which the solid solutions undergo the superionic transition (2500–3300 K). Similarly, a spike in the specific heat, associated with the superionic transition, occurs at lower temperatures in solid solutions that have a high U content. Correspondingly, oxygen diffusivity is higher in pure UO 2 than in pure ThO 2 . Furthermore, at temperatures below the superionic transition, oxygen mobility is notably higher in solid solutions than in the end members. Enhanced diffusivity is promoted by lower oxygen-defect enthalpies in (U x ,Th 1− x )O 2 solid solutions. Unlike in UO 2 and ThO 2 , there is considerable variety of oxygen vacancy and oxygen interstitial sites in solid solutions generating a wide range of property values. Trends in the defect enthalpies are discussed in terms of composition and the lattice parameter of (U x ,Th 1− x )O 2 .

scholarly journals Calculation of thermal expansion, glass transition temperature and glass density in the system RO–Al2O3–B2O3–SiO2 (where RO=BaO, SrO, CaO, MgO, ZnO)

2020 ◽  
pp. 69-74
Author(s):  
E.V. Karasik ◽  
◽  
Yu.S. Hordieiev ◽  
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mathematical Models ◽  
Temperature Coefficient ◽  
Linear Expansion ◽  
Experimental Sample ◽  
Wide Range ◽  
Coefficient Of Linear Expansion

Glasses of the system RO–Al2O3–B2O3–SiO2 are used as a base for the fabrication of heat-resistant nonmetallic materials and general-purpose products. The purpose of this work is to develop mathematical models for calculating the temperature coefficient of linear expansion, glass transition temperature and density as a function of the composition of glass in the oxide system RO–Al2O3–B2O3–SiO2 where RO=BaO, SrO, CaO, MgO, ZnO. The disadvantage of the known models is that the range of their application is limited by the quantitative content of components in the glass. At the same time, an increase in the sample size of experimental compositions made it possible to obtain more accurate mathematical models for calculating these properties. The glasses included in the experimental sample are distinguished by a wide range of temperature coefficient of linear expansion (from 30 to 10510–7 К–1). The glass transition temperature of these glasses is within the range of 580–7100C, which allows a reasonable approach to the choice of temperature regime for the formation of the structure vitreous and glass-ceramic materials for different functional purposes. The mathematical models were developed with the use of the experimental and statistical method. The obtained mathematical models are adequate to the experimental data and allow calculating the thermal expansion, glass transition temperature and density of glasses; the mean-square deviations of temperature coefficient of linear expansion, glass transition temperature and density being 1.910–7 К–1, 16.00C and 0.06 g cm–3, respectively. Their accuracy is sufficient for the development of basic glass compositions for various functional purposes.

Thermal expansion of bulk amorphous Zr41.2Ti13.8Cu12.5Ni10Be22.5 alloy

1996 ◽  
Vol 11 (7) ◽  
pp. 1836-1841 ◽  
Author(s):  
Y. He ◽  
R. B. Schwarz ◽  
D. G. Mandrus
Keyword(s):  
Heat Capacity ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Amorphous Alloy ◽  
Crystallization Temperature ◽  
Linear Thermal Expansion ◽  
Undercooled Liquid ◽  
Small Viscosity

The linear thermal expansion of the bulk amorphous Zr4.12Ti13.8Cu12 5Ni10Be22.5 (atomic percent) alloy has been measured from 80 K to 773 K. The data for T, Tg were fitted by a model based on the Grüneisen relation and a Debye expression for the heat capacity. From the fit, we deduced the Grüneisen parameter, g = 1.25, and the Debye temperature, QD = 400 K. Annealing the amorphous alloy at 663 K, which is between the glass transition temperature Tg = 623 K and the crystallization temperature Tx = 693 K, causes viscous flow in the sample. This is due to the small viscosity in the undercooled liquid.

The low temperature hexagonal to orthorhombic transformation in Si3N4 reinforced BAS matrix composites

1995 ◽  
Vol 10 (5) ◽  
pp. 1256-1263 ◽  
Author(s):  
A. Bandyopadhyay ◽  
P.B. Aswath ◽  
W.D. Porter ◽  
O.B. Cavin
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Dimensional Change ◽  
Matrix Composites ◽  
Sintering Time

The amount of Si3N4 in a Si3N4-BaO · Al2O3 · 2SiO2 (BAS) composite and the time of sintering was examined in the context of the low temperature hexagonal to orthorhombic transformation in BAS. It was found that with increasing amounts of Si3N4 in the composite, the temperature of the hexagonal to orthorhombic transformation was decreased. As the sintering time was increased for a given composite composition, a drop in the temperature of the hexagonal to orthorhombic transformation was observed. which was linked to an increase in the β-Si3N4 content in the composite. In addition, as the Si3N4 content in the composite was increased, a resultant drop in the coefficient of thermal expansion of the composite occurred. The extent of the linear dimensional change of the composite during the BAS hexagonal to orthorhombic transformation is reported.

THERMAL EXPANSION, GRUENEISEN PARAMETER, AND TEMPERATURE DEPENDENCE OF LATTICE VIBRATION FREQUENCIES OF ALUMINUM OXIDE

1965 ◽  
Vol 43 (4) ◽  
pp. 523-531 ◽  
Author(s):  
Alois Schauer
Keyword(s):  
Thermal Expansion ◽  
Aluminum Oxide ◽  
Temperature Dependence ◽  
Lattice Vibration ◽  
Linear Thermal Expansion ◽  
Vibration Frequencies ◽  
Polycrystalline Aluminum ◽  
Interferometric Method ◽  
Temperature Range ◽  
Wide Range

The linear thermal expansion coefficient of polycrystalline aluminum oxide has been measured in the temperature range from 100 °K to 1 500 °K by an interferometric method. The interferometer used is capable of giving high accuracy over a wide range of temperatures, and is described in some detail. The Grueneisen parameter of aluminum oxide is calculated and found to be 1.35 ± 0.05 over the whole temperature range. There is no significant change, such as might be expected from theory, of the Grueneisen parameter around 0.2 × Debye temperature. Based on the formulae given in an earlier publication, the temperature dependence of lattice vibration frequencies of aluminum oxide is calculated.

The linear thermal expansion of bulk nanocrystalline Al and SS304 at low temperature

2011 ◽  
Vol 406 (14) ◽  
pp. 2758-2762 ◽  
Author(s):  
S.G. Wang ◽  
R.J. Huang ◽  
Y. Mei ◽  
K. Long ◽  
L.F. Li ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Linear Thermal Expansion ◽  
Bulk Nanocrystalline

scholarly journals RELaTED Project: New Developments on Ultra-Low Temperature District Heating Networks

Proceedings ◽  
2020 ◽  
Vol 65 (1) ◽  
pp. 25
Author(s):  
Antonio Garrido Marijuan ◽  
Roberto Garay ◽  
Mikel Lumbreras ◽  
Víctor Sánchez ◽  
Olga Macias ◽  
...  
Keyword(s):  
Low Temperature ◽  
High Performance ◽  
Waste Heat ◽  
District Heating ◽  
Hot Water ◽  
Thermal Systems ◽  
Heating Source ◽  
Wide Range ◽  
Thermal Sources ◽  
Heating Networks

District heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning district heating-connected reversible heat pump systems that allow to reach adequate thermal levels for domestic hot water as well as the use of the network for district cooling with high performance. These developments will be demonstrated in four locations: Estonia, Serbia, Denmark, and Spain.

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