Specific Heat of Natural Rubber

1951 ◽  
Vol 24 (2) ◽  
pp. 285-289 ◽  
Author(s):  
Hiroshi Ichimura
Keyword(s):  
Low Temperature ◽  
Natural Rubber ◽  
Specific Heat ◽  
Constant Pressure ◽  
Constant Volume ◽  
Theoretical Considerations

Abstract The constant volume specific heat of natural rubber is calculated from the constant pressure specific heat, which is measured experimentally, and it is shown that the low temperature part is expressed by a combination of the Debye and Einstein formulas. Some theoretical considerations on the transition phenomena at 200° K are included.

FALSIFICATIONS OF POISSON ADIABATE, HUGONIO ADIABATE, LAPLACE SOUND SPEEDS. MODERNIZATION OF FOUNDATIONS OF THERMODYNAMICS

2020 ◽  
Vol 5 (333) ◽  
pp. 58-67
Author(s):  
K.B. Jakupov ◽  
Keyword(s):  
Shock Wave ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Speed Of Sound ◽  
Constant Pressure ◽  
Energy Balance Equation ◽  
Ideal Gas ◽  
Constant Volume ◽  
Capacity Coefficient

The inequality of the universal gas constant of the difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume is proved. The falsifications of using the heat capacity of a gas at constant pressure, false enthalpy, Poisson adiabat, Laplace sound speed, Hugoniot adiabat, based on the use of the false equality of the universal gas constant difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume, have been established. The dependence of pressure on temperature in an adiabatic gas with heat capacity at constant volume has been established. On the basis of the heat capacity of a gas at a constant volume, new formulas are derived: the adiabats of an ideal gas, the speed of sound, and the adiabats on a shock wave. The variability of pressure in the field of gravity is proved and it is indicated that the use of the specific coefficient of ideal gas at constant pressure in gas-dynamic formulas is pointless. It is shown that the false “basic formula of thermodynamics” implies the falseness of the equation with the specific heat capacity at constant pressure. New formulas are given for the adiabat of an ideal gas, adiabat on a shock wave, and the speed of sound, which, in principle, do not contain the coefficient of the specific heat capacity of a gas at constant pressure. It is shown that the well-known equation of heat conductivity with the gas heat capacity coefficient at constant pressure contradicts the basic energy balance equation with the gas heat capacity coefficient at constant volume.

Thermodynamics of Elasticity of Natural Rubber

1964 ◽  
Vol 37 (3) ◽  
pp. 606-616
Author(s):  
Geoffrey Allen ◽  
Umberto Bianchi ◽  
Colin Price
Keyword(s):  
Natural Rubber ◽  
Direct Measurement ◽  
Constant Pressure ◽  
Elastic Force ◽  
Constant Volume

Abstract The thermoelasticity of a natural rubber strip held in simple elongation at constant volume has been studied experimentally. From the direct measurement of (∂f/∂T)L,V the energetic and entropic contributions to the total elastic force have been evaluated. The results agree with indirect estimates based on data obtained at constant pressure, the energetic contribution to the elastic force being some 20%. The dilation coefficient for natural rubber has also been obtained in a subsidiary experiment.

scholarly journals Note on the monatomicity of neon, krypton, and xenon

1912 ◽  
Vol 86 (584) ◽  
pp. 100-101 ◽  
Keyword(s):  
Specific Heat ◽  
Constant Pressure ◽  
Constant Volume ◽  
Insufficient Evidence ◽  
Polyatomic Gas ◽  
Considerable Portion

The monatomicity of neon, krypton, and xenon has been taken for granted on somewhat insufficient evidence. When the memoir on Argon and its companions was written it was stated that no experiments with the pure gases had been carried out on the ratio between the specific heat at constant volume and constant pressure, but that measurements made with impure samples indicated the ratio 1.67; and it was remarked that such a ratio could not have been found had any considerable portion of the mixture consisted of a polyatomic gas. Having now at my disposal relatively large quantities of pure neon, which had served Mr. Watson, and of pure krypton and pure xenon, which had served Prof. Moore, for determining the densities of these gases, it appeared advisable to fill the gaps in our knowledge of their specific heat ratios.

scholarly journals The homogeneity of helium and of argon

1897 ◽  
Vol 60 (359-367) ◽  
pp. 206-216 ◽  
Keyword(s):  
Molecular Weight ◽  
Specific Heat ◽  
Constant Pressure ◽  
Atomic Weight ◽  
Constant Volume ◽  
Molecular Weights

It was pointed out by Lord Rayleigh and one of the authors that it is a legitimate conclusion to draw, from the found ratio between its specific heat at constant pressure and that at constant volume, that argon is a monatomic element (‘Phil. Trans.,’ 1895, A, p. 235). A similar deduction can be drawn regarding helium (‘Chem. Soc. Trans.,’ 1895, p. 699). And as the molecular weight of hydrogen is accepted as twice its atomic weight, and as the density of helium is approximately 2, and that of argon approximately 20, the molecular weights of these elements are approximately 4 and 40 respectively. If, however, the molecule is identical with the atom, then the atomic weights must also necessarily be 4 and 40.

The thermodynamic properties of fluid helium

1960 ◽  
Vol 252 (1013) ◽  
pp. 357-395 ◽  
Keyword(s):  
Thermodynamic Properties ◽  
Specific Heat ◽  
Internal Energy ◽  
Thermodynamic Functions ◽  
Single Phase ◽  
Constant Pressure ◽  
Pressure Coefficient ◽  
Differential Method ◽  
Constant Volume ◽  
Gibbs Function

Measurements have been made from which all the thermodynamic properties of fluid helium can be calculated in the temperature range from 3 to 20 °K and up to 100 atm pressure. The quantities measured were: (i) the specific heat at constant volume as a function of temperature and density, (ii) the pressure coefficient at constant volume ( also as a function of temperature and density, (iii) the pressure as a function of temperature at constant volume (isochores) for a range of densities. A particular feature of the experiments is that the important derivative ( )v, from which the changes of entropy and internal energy with volume at constant temperature are calculated, was measured directly by a differential method. Starting from the known entropy and internal energy of the liquid near its normal boiling point, these two quantities were calculated for all single phase states within the experimental range. From these, and using the equation of state data, the enthalpy, free energy, Gibbs function, and the specific heat at constant pressure have been deduced. The thermodynamic functions, together with some useful state properties, are tabulated as functions of temperature and either volume or pressure as relevant. The choice of the measured quantities was such that all the thermodynamic functions except the specific heat at constant pressure were obtained by integration of the experimental data; these functions therefore have the same accuracy as the measured quantities, about 1 %.

Isentropic Expansion and the Three Isentropic Exponents of R152a

1999 ◽  
Author(s):  
D. A. Kouremenos ◽  
X. K. Kakatsios ◽  
O. E. Floratos ◽  
G. Fountis
Keyword(s):  
Specific Heat ◽  
Vapor Phase ◽  
Constant Pressure ◽  
Initial Pressure ◽  
Ideal Gas ◽  
Constant Volume ◽  
State Equations ◽  
Real Gas ◽  
Isentropic Expansion ◽  
The Ideal

Abstract The isentropic change of an ideal gas is described by the well known relations pvk = const., Tv(k-1) = const. and p(1-k)Tk = const., where the exponent k is defined as the ratio of the constant pressure to the constant volume specific heat, k = Cp/Cv. The same relations can be used for real gases only if the differential isentropic changes under consideration are small. A better examination of the differential isentropic change shows that for p, v, T systems, there are three different isentropic exponents corresponding to each pair formed out of the variables p, v, T. These three exponents noted kT,p, kT,v, kp,v after the corresponding pair of variables used, are interconnected by one relation, and accordingly only two out of the three are independent. The analysis of the present paper shows the numerical values of these exponents as well as the isentropic expansion ratios for R152a in the vapor phase, presented in diagram form. It can be seen that the deviations of the three isentropic exponents relative to the conventional k = Cp/Cv values are considerable and depend upon the initial pressure and the stage of the expansion. Additionally, the effect of the three isentropic exponents on the ideal gas relations describing the isentropic expansion ratios is examined, in order to develop simple yet more accurate relations without having to resort to the complex real gas state equations.

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