The Contribution of Internal Energy to the Elastic Force of Natural Rubber

1963 ◽  
Vol 36 (2) ◽  
pp. 351-364
Author(s):  
R.-J. Roe ◽  
W. R. Krigbaum
Keyword(s):  
Natural Rubber ◽  
Internal Energy ◽  
Elastic Force

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.

Thermoelastic Properties of Noncrystallizing Rubber

1951 ◽  
Vol 24 (2) ◽  
pp. 328-335
Author(s):  
G. M. Bartenev
Keyword(s):  
Experimental Data ◽  
Internal Energy ◽  
Elastic Deformation ◽  
Elastic Force ◽  
Equilibrium Isotherms ◽  
Thermoelastic Properties ◽  
A Value ◽  
Comparison Of The Results ◽  
Thermodynamic Equations ◽  
Butadiene Styrene

Abstract 1. A method of measuring and obtaining the equilibrium isotherms of strain for vulcanized butadiene-styrene rubber is described. 2. It is shown that the component of the elastic force of the rubber which depends on the internal energy has a value of several per cent. 3. Calculation shows that the change in the volume of uncrystallizable rubber, at 300 per cent strain, has a value less than 0.1 per cent. 4. A comparison of the results obtained with the thermodynamic equations shows that the deformation of the rubber investigated can be considered strictly high elastic and entropic. 5. A comparison of the experimental data with the theory of high elastic deformation confirms the accuracy of the conclusions from the theory.

Thermoelastic Behavior of Natural Rubber

1969 ◽  
Vol 42 (3) ◽  
pp. 835-849
Author(s):  
Mitchel C. Shen ◽  
Donald A. McQuarrie ◽  
Julius L. Jackson
Keyword(s):  
Statistical Theory ◽  
Natural Rubber ◽  
Temperature Coefficient ◽  
Internal Energy ◽  
Controlled Environment ◽  
Energy Contribution ◽  
Elongation Ratio ◽  
Chemical Effects ◽  
Nonequilibrium Conditions ◽  
Exact Derivation

Abstract Stress—temperature measurements of natural rubber were carried out up to the elongation ratio, α, of 2.0. An automatic stress relaxometer was constructed for this purpose which can be completely enclosed in a controlled environment. Experiments were so conducted as to minimnze possible chemical effects and nonequilibrium conditions. Relative internal energy contribution to stress, fe/f, is calculated as a function of α in terms of statistical and thermodynamic theories. Both of these yield similar results. It is shown that in the region of low strains (1.0<α<1.5),fe/f decreases rapidly with increasing α, but appears to remain constant at 1.5<α<2.0. This observation is not in agreement with the prediction of the current statistical theory of rubber elasticity, which stipulates that the energy effects are intramolecular and independent of deformation. Implications of these findings are discussed. It is suggested that perhaps at low strains the intermolecular interactions are large in comparison with intramolecular energies, but become relatively insignificant at higher elongation ratios. The temperature coefficient of unperturbed chain dimensions is also calculated from thermoelastic data. It is constant only in the region 1.5<α<2.0. Finally, a new, more exact derivation of the Elliott—Lippmann anisotropy factor in terms of the statistical theory is given in the Appendix.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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