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.

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.

Apparatus for the Direct Determination of the Dynamic Bulk Modulus

1957 ◽  
Vol 30 (2) ◽  
pp. 449-459
Author(s):  
J. E. McKinney ◽  
S. Edelman ◽  
R. S. Marvin
Keyword(s):  
Natural Rubber ◽  
Bulk Modulus ◽  
Direct Measurement ◽  
Static Pressure ◽  
Direct Determination ◽  
Preliminary Evaluation ◽  
Air Bubbles ◽  
Frequency Range ◽  
Piezoelectric Crystals

Abstract An apparatus has been developed for the direct measurement of the real and imaginary parts of the dynamic bulk modulus of solid and liquid materials over the frequency range of 50 to 10,000 cps. Piezoelectric crystals serving as driver and detector, together with the sample and a confining liquid, are contained in a cavity small compared with the wavelength of sound at these frequencies. Static pressure is superposed to eliminate the effect of small air bubbles. The complex compliances of the sample, confining liquid, and the cavity, are additive in this region, where the compliance is pure dilatation. The dynamic compliances of several natural rubber-sulfur mixtures were obtained in a preliminary evaluation of the behavior of the apparatus.

scholarly journals On the temperature variation of the specific heats of hydrogen and nitrogen

1930 ◽  
Vol 126 (801) ◽  
pp. 204-212 ◽  
Keyword(s):  
Kinetic Theory ◽  
Temperature Variation ◽  
Characteristic Equation ◽  
Constant Pressure ◽  
Ideal Gas ◽  
Constant Volume ◽  
Specific Heats

The energy of a gram molecule of an ideal gas can be calculated from the kinetic theory. From this, by the application of the Maxwell-Boltzmann hypothesis, the molecular specific heats at constant volume, S v , of ideal monatomic and diatomic gases are deduced to be 3R /2 and 5R/2 respectively at all temperatures. R is the gas constant per gram molecule = 1⋅985 gm. cal./° C. The corresponding molecular specific heats at constant pressure, S p , can be obtained by the addition of R. In the case of real gases, which obey some form of characteristic equation other than P. V = R. T, it can be shown from thermodynamical considera­tions that the value of S p depends upon the pressure, but as the term involving the pressure also includes the temperature, S p is not independent of the tempera­ture but it increases in value as the temperature is reduced. Assuming the characteristic equation proposed by Callendar, i. e. , v - b ­­= RT/ p - c (where b is the co-volume, c is the coaggregation volume which is a function of the temperature of the form c = c 0 (T 0 /T) n , n being dependent on the nature of the gas), it is easy to show from the relation (∂S p /∂ р ) T = -T(∂ 2 ν /∂Τ 2 ) р , hat S p = S p 0 + n (n + 1) cp /T; and, by combining this with S p – S v = T(∂ p /∂Τ) v (∂ v /∂Τ) p = R(1 + ncp /RT) 2 , the corresponding values of S v can be obtained.

scholarly journals Thermodynamics and dynamics of a monoatomic glass former. Constant pressure and constant volume behavior

2008 ◽  
Vol 128 (14) ◽  
pp. 144505 ◽  
Author(s):  
Vitaliy Kapko ◽  
Dmitry V. Matyushov ◽  
C. Austen Angell
Keyword(s):  
Constant Pressure ◽  
Constant Volume ◽  
Thermodynamics And Dynamics

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.

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