Thermodynamic Properties of Natural Rubber and Isoprene

1966 ◽  
Vol 39 (1) ◽  
pp. 143-148 ◽  
Author(s):  
R. W. Warfield ◽  
M. C. Petree
Keyword(s):  
Free Energy ◽  
Glass Transition ◽  
Thermodynamic Properties ◽  
Natural Rubber ◽  
Specific Heat ◽  
Gibbs Free Energy ◽  
Kcal Mole ◽  
Specific Heat Data ◽  
Temperature Range ◽  
Heat Data

Abstract Using published specific heat data, the entropy, enthalpy, and Gibbs free energy of natural rubber (NR) have been calculated over the temperature range 0 to 320° K. The thermodynamic function Cp/T as a function of T calculated for NR exhibits a maximum at 50° K and another maximum at 210° K, which is associated with the glass transition. The number of classically vibrating units per repeating unit of NR is 6.61 at 300° K. These functions have also been calculated for isoprene over the temperature range 0 to 300° K. At 298.16° K the entropy of polymerization was found to be 24.00 cal mole−1deg−1 and the free energy of polymerization − 10.7 kcal/mole.

scholarly journals Thermal Expansion of Fe2MnSi

1988 ◽  
Vol 41 (6) ◽  
pp. 781 ◽  
Author(s):  
JR Miles ◽  
TF Smith ◽  
TR Finlayson
Keyword(s):  
Thermal Expansion ◽  
Curie Temperature ◽  
Specific Heat ◽  
Grüneisen Parameter ◽  
Specific Heat Data ◽  
Thermal Expansion Data ◽  
Narrow Peak ◽  
Temperature Range ◽  
Weak Anomaly ◽  
Heat Data

Measurements of the thermal expansion of FezMnSi in the temperature range 200-300 K are reported. A large, relatively narrow peak is found at the magnetic re-ordering temperature in contrast to a broad, weak anomaly at the Curie temperature. Values for the magnetic Gruneisen parameter 'Y m are derived from the thermal expansion data and previously reported specific heat data following the subtraction of a non-magnetic background.

Formulations for the Thermodynamic Properties of Pure Substances

2005 ◽  
Vol 127 (1) ◽  
pp. 83-87 ◽  
Author(s):  
George A. Adebiyi
Keyword(s):  
Thermodynamic Properties ◽  
Specific Heat ◽  
Constant Pressure ◽  
Equations Of State ◽  
Virial Coefficients ◽  
Data Correlation ◽  
Specific Heat Data ◽  
Pvt Data ◽  
Pure Substances ◽  
Heat Data

This article presents a procedure for formulation for the thermodynamic properties of pure substances using two primary sets of data, namely, the pvT data and the specific heat data, such as the constant-pressure specific heat cp as a function of pressure and temperature. The method makes use of a linkage, on the basis of the laws of thermodynamics, between the virial coefficients for the pvT data correlation and those for the corresponding specific heat data correlation for the substance. The resulting equations of state take on remarkably simple analytic forms that give accurate predictions over the range of input data employed.

Formulations for the Thermodynamic Properties of Pure Substances

2003 ◽  
Author(s):  
George A. Adebiyi
Keyword(s):  
Thermodynamic Properties ◽  
Specific Heat ◽  
Constant Pressure ◽  
Equations Of State ◽  
Property Values ◽  
Complete Analysis ◽  
Specific Heat Data ◽  
Pvt Data ◽  
Pure Substances ◽  
Heat Data

Complete analysis of thermodynamic systems generally requires knowledge of the property values of substances at different states. Performing such analysis on the computer is facilitated if the equations of state for the substances are available in relatively simple analytic forms. This article presents a procedure for formulation for the thermodynamic properties of pure substances using two primary sets of data, namely the pvT data and the specific heat data such as the constant-pressure specific heat, cp, as a function of pressure and temperature. By developing a correlation of the pvT data in the virial form of equation of state, an appropriate corresponding correlation can be determined for the specific heat of the substance on the basis of the laws of thermodynamics. The resulting equations of state take on remarkably simple analytic forms that give accurate predictions over the range of input data employed.

scholarly journals First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1404
Author(s):  
Yunfei Yang ◽  
Changhao Wang ◽  
Junhao Sun ◽  
Shilei Li ◽  
Wei Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Vibrational Entropy ◽  
Functional Theory ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Ductile Behavior ◽  
Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

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.

Specific heat data of high-Tc superconductors: Lattice and electronic contributions

1989 ◽  
Vol 69 (6) ◽  
pp. 625-629 ◽  
Author(s):  
J.E. Gordon ◽  
M.L. Tan ◽  
R.A. Fisher ◽  
N.E. Phillips
Keyword(s):  
Specific Heat ◽  
High Tc Superconductors ◽  
Specific Heat Data ◽  
High Tc ◽  
Heat Data

THE COMBINED ANALYSIS OF SPECIFIC HEAT AND THERMAL EXPANSION OF Nd1−xLuxMn2 COMPOUNDS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 810-813
Author(s):  
N.H. KIM-NGAN ◽  
P.E. BROMMER ◽  
J.J.M. FRANSE
Keyword(s):  
Magnetic Properties ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Crystal Field ◽  
Spin Fluctuation ◽  
Spin Reorientation ◽  
Antiferromagnetic Order ◽  
Combined Analysis ◽  
Temperature Range

Specific heat and thermal expansion measurements have been performed on Nd1−xLUxMn2 in the temperature range between 1.5K and 300K. Below 10K, anomalies are observed which are ascribed to a spin reorientation of the Nd sublattice. These anomalies are only slightly affected by the substitution of Nd by Lu. Large effects, however, are observed on the magnetic properties of the Mn sublattice. The antiferromagnetic order disappears for x exceeding 0.30. The data are analysed in terms of Grüneisen parameters. In the paramagnetic compound LuMn2, a spin-fluctuation contribution to the thermodynamic properties is observed. In the Nd-containing compounds, distinct contributions from the crystal field acting on the Nd ions can be distinguished. The variation of the magnetic properties of the Mn sublattice with the concentration of Lu is discussed.

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