The Chemistry of Soft Rubber Vulcanization. III. Comparison of Vulcanized Rubber with Unmilled Crude Rubber Reclaims, and Unvulcanized Stocks Containing Stiffeners or Gas Black

1934 ◽  
Vol 7 (3) ◽  
pp. 538-545
Author(s):  
B. S. Garvey
Keyword(s):  
Standard Method ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Soft Rubber

Abstract IN PART I (1) of this series it was pointed out that the measurement of vulcanization is complicated by the use of unmilled rubber (e. g., latex stocks), stiffeners, gas black, and reclaims. Therefore limitations in compounding were accepted and a standard method of processing was adopted. These limitations were accepted in recognition of the fact that compounds containing these materials show some properties akin to those of vulcanized rubber. For example, some crude rubbers have stress-strain characteristics almost identical with those of certain types of vulcanizate. Uncured gas black stocks likewise show some of the characteristics of vulcanized rubber, and the reënforcing action of gas black is sometimes spoken of as a sort of vulcanization (2). Such limitations are desirable only if it can be shown that the phenomena excluded are different from those being studied. The experiments reported in this paper show how the tough, hard, crude rubbers can be differentiated from vulcanized rubber and how the effect of gas black and stiffeners can be differentiated from that of vulcanization. The generally accepted view that reclaims are distinct in character from either vulcanized or unvulcanized rubber is supported by this investigation. The. experiments also show why it is desirable, for the present, to exclude these materials from the compounds used to study vulcanization.

The Influence of the Test-Specimen on the Results Obtained In Tensile Tests of Soft Vulcanized Rubber Mixtures

1953 ◽  
Vol 26 (2) ◽  
pp. 465-480
Author(s):  
R. Herzog ◽  
R. H. Burton
Keyword(s):  
Natural Rubber ◽  
Tensile Properties ◽  
Test Specimen ◽  
Tensile Tests ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Different Types ◽  
Small Test ◽  
Soft Rubber

Abstract The small test-specimen of the VSM-1 type should not be used for measuring the tensile properties of pure-gum vulcanizates; instead, the VSM-1a type of test-specimen should be used for such vulcanizates. Results obtained with the different types of test-specimen differ greatly; hence, in reporting the results of any tests of this kind, the type of test-specimen used should be stated, and only results obtained with one particular type of test-specimen should be compared. For example, substitution of the VSM-2 type of test-specimen by the KTA-II type of test-specimen, which is of approxmately the same size, unfortunately does not result in any better agreement. Based on these differences, which in the case of natural rubber have been found to vary from one type of vulcanizate to another, it is natural to expect corresponding unpredictable differences with various synthetic elastomers. The determination of stress-strain properties of soft rubber vulcanizates is, therefore, fundamentally a problem of agreement on methods of testing, i.e., of standardization.

The Oil Resistance of Rubber. I Study of the Swelling of Vulcanized Rubber

1936 ◽  
Vol 9 (1) ◽  
pp. 70-73
Author(s):  
Yoshio Tanaka ◽  
Shû Kambara ◽  
Jirô Noto
Keyword(s):  
Molecular Structure ◽  
Elastic Properties ◽  
Mixed Solvents ◽  
Experimental Results ◽  
Stress Strain ◽  
Oil Resistance ◽  
Effect Of Solvents ◽  
Vulcanized Rubber

Abstract To study the effect of solvents on the elastic properties of vulcanized rubber, the following three points were investigated. 1. The swelling maximum obtained by various mixed solvents. 2. The stress-strain curves of rubber swollen to different degrees. 3. Time-swelling and time-deswelling curves. The spiral theory of molecular structure of rubber proposed by Fikentscher and Mark is utilized to explain the experimental results.

The Behavior of Raw Rubber When Stretched Isothermally

1938 ◽  
Vol 11 (4) ◽  
pp. 647-652 ◽  
Author(s):  
H. Hintenberger ◽  
W. Neumann
Keyword(s):  
Room Temperature ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Steep Ascent ◽  
Flow Effect ◽  
Vulcanized Rubber ◽  
Flow Phenomena ◽  
Entropy Effect ◽  
The Subject

Abstract The S-shaped form of the stress-strain curve of rubber is today explained in a quite satisfactory way. In the first part of the curve, i. e., the gradual ascent, work must be expended because of the van der Waals forces of attraction of the molecules; in the second part, i. e., the steep ascent, the elasticity is chiefly an entropy effect, which is finally exceeded by crystallization phenomena. The phenomenon of crystallization itself has been the subject of extensive investigations, but in most cases vulcanized rubber has been employed, and because of the various accelerators and fillers which the rubber has contained, the products have been rather ill-defined. It is evident that the phenomena involved in crystallization would be much more clearly defined if the substance under investigation were to be in a higher state of purity. If experiments are carried out with raw rubber, a flow effect is added to the various other phenomena. As a result of this flow effect, Rosbaud and Schmidt, and Hauser and Rosbaud as well, found that the stress-strain curve depends on the rate of elongation at very low extensions, with a greater stiffness at high rates of elongation. As found recently by Kirsch, there is no evidence of any flow phenomena in vulcanized rubber at room temperature. Most investigations have been so carried out that the stress has been measured at a definite elongation. It was therefore of interest to determine the elongation at constant stress, and the changes in this relation with time and with temperature, of various types of raw rubber.

Characteristic Properties of Rubber at Low Temperatures. A Discussion of the Stress-Strain Curves of Vulcanized Rubber at Low Temperatures

1934 ◽  
Vol 7 (4) ◽  
pp. 610-617 ◽  
Author(s):  
Takeo Fujiwara ◽  
Toramatsu Tanaka
Keyword(s):  
Physical Properties ◽  
Low Temperatures ◽  
External Heat ◽  
Point Of View ◽  
Special Importance ◽  
Stress Strain ◽  
Experimental Proof ◽  
Vulcanized Rubber ◽  
The Subject ◽  
Two Phases

Abstract The hardening of rubber at low temperatures is one of the well-known physical characteristics of rubber. The loss of elasticity of raw rubber by hardening at 0° to 10° C., its turning to the consistency of glass, and its fragility at −19° C. when cooled with liquid air, and its fibering when stretched to 60–70 per cent previous to breaking, give an experimental proof of the theory of the structure of rubber molecules. Vulcanization makes raw rubber physically less sensitive to heat and to low temperatures, and is of great significance, because it enables vulcanized rubber to be used around −30° C. without losing its elasticity. The effect of external heat on the physical properties, especially on the stress-strain relations, of vulcanized rubber has been discussed mainly for temperatures from −10° to +100° C., and only two papers deal with temperatures from −30° to −60° or −70° C. (cf. Le Blanc and Kröger, Kolloid Z., 37, 205 (1925); Tener, Kingsbury and Holt, Bureau of Standards Technologic Papers Vol. 22, No. 364). Of special importance are a means of recognizing changes m the physical properties (phenomenon of freezing-hard ness) of vulcanized rubber at −30° to −60° or −70° C., and the practical value of such information. Though there is a contradiction in the fundamental meaning of the “cold resistant theory” of rubber, investigations of the two phases of the subject may throw some light on practical problems and widen the scientific point of view.

Reinforcement of Butyl with Carbon Black. II. Thermally vs. Chemically Oxidized Blacks

1964 ◽  
Vol 37 (4) ◽  
pp. 1034-1048 ◽  
Author(s):  
A. M. Gessler
Keyword(s):  
Carbon Black ◽  
Chemical Reactivity ◽  
Preceding Paper ◽  
Strain Curve ◽  
Convincing Evidence ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Carbon Particles ◽  
Vulcanized Rubber ◽  
Oxygen Functionality

Abstract The effect of oxidized blacks on the stress-strain properties and bound-rubber content of butyl and SBR was discussed in the preceding paper. Oxidized blacks, when compared with similar untreated blacks, were shown to have a greatly increased reinforcing capacity in butyl. Oxygen functionality on carbon black, it was therefore concluded, is essential in butyl to produce the chemical reactivity which is required between polymer and black if high-order reinforcement is to be obtained. Oxygen functionality on carbon black, it was also demonstrated, is not only not required for enhanced reinforcement in SBR, but it is in fact a deterrent, because it exerts severe restraining effects on the cure of the resulting vulcanizates as well. These interesting results were proposed to provide qualitative but convincing evidence that carbon-polymer bonding, which we believe is requisite to reinforcement, is achieved by different mechanisms in butyl and SBR. In butyl, the unique sensitivity of the stress-strain curve to reinforcing effects was used to speculate on the disposition of carbon blacks in “filled” and reinforced vulcanizates, respectively. With oxidized blacks, reinforcement effects were pictured as stiffening effects which, starting with the gum vulcanizates, caused the stress-strain curve to be shifted without intrinsic changes in its shape. The resulting “reinforced gum,” it was suggested, derived its physical characteristics from the fact that carbon black was included in the vulcanized rubber network. With untreated blacks, in “filled” systems, carbon black was pictured as being enmeshed or entangled in an independently formed vulcanized rubber network. The stiffening effects in this case were attributed to viscous contributions arising from steric restrictions which the occluded carbon particles were thought to impose on both initial movements and the subsequent orientation of network chains when the sample was extended.

Stress-Strain Data for Vulcanized Rubber under Various Types of Deformation

1944 ◽  
Vol 17 (4) ◽  
pp. 813-825 ◽  
Author(s):  
L. R. G. Treloar
Keyword(s):  
Mechanical Properties ◽  
Network Model ◽  
Large Deformations ◽  
Pure Shear ◽  
Molecular Network ◽  
Satisfactory Explanation ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Strain Data ◽  
Good For

Abstract Stress-strain data are given for two types of vulcanized rubber: (1) an 8% S rubber, and (2) a latex rubber. The types of deformation studied were simple elongation, 2-dimensional extension (or compression), pure shear, and combined elongation and shear. Comparison with the theoretical relations based on the molecular-network model shows the agreement to be good for the 2-dimensional extension, but less good for simple elongation and shear. The effect of combined elongation and shear is satisfactorily accounted for. It is concluded that the theory provides a satisfactory explanation of rubberlike elasticity, and forms a useful basis for the description of the mechanical properties of rubber subjected to large deformations of any type.

Stress-Strain Properties of Natural Rubber under Biaxial Strain

1951 ◽  
Vol 24 (1) ◽  
pp. 70-82 ◽  
Author(s):  
B. B. S. T. Boonstra
Keyword(s):  
Natural Rubber ◽  
Biaxial Strain ◽  
Stress Strain ◽  
Relaxation Constant ◽  
Vulcanized Rubber ◽  
Stress Curve

Abstract (1) The stress-strain curves of vulcanized rubber held at definite tangential elongations during stretching differ more from the simple unidirectional-extension-stress curve than the theory predicts. The differences are larger at higher tangential elongations. (2) The relaxation constant determined at 600 per cent elongation is practically unaffected by tangential elongations up to 300 per cent.

Isothermal and Adiabatic Stress-Strain Curves of Vulcanized Rubber

1939 ◽  
Vol 12 (1) ◽  
pp. 64-70 ◽  
Author(s):  
V. Hauk ◽  
W. Neumann
Keyword(s):  
Chemical Nature ◽  
Absolute Temperature ◽  
Strain Diagram ◽  
Stress Strain ◽  
Isothermal Conditions ◽  
Adiabatic Conditions ◽  
Vulcanized Rubber ◽  
The Subject ◽  
The Difference ◽  
Thermodynamic Interpretation

Abstract The stress-strain diagram of rubber has been the subject of a large number of investigations, including those of Röntgen, Gough, and Joule in the nineteenth century, those on isothermal phenomena by Meyer and Ferri, and Wiegand and Snyder, and most recently those on adiabatic phenomena of Ornstein, Eymers, and Wouda. The investigations of Meyer and Ferri are concerned chiefly with the dependence of the stress-strain phenomena on the temperature, and they confirm experimentally the hypothesis that within a certain range of temperature and with highly vulcanized samples, the stress is proportional to the absolute temperature, i. e., S=aT+b. At lower states of vulcanization this proportionality does not hold true. The work of Ornstein and his collaborators, which is frequently cited in the literature, is concerned with the phenomena which take place when raw rubber and weakly vulcanized rubber are stretched adiabatically; that of Wiegand and Snyder is concerned chiefly with a thermodynamic interpretation of stress-strain curves obtained experimentally. Now in spite of the fact that stress-strain curves of rubber have been determined so frequently, particularly under isothermal conditions, these measurements are for the most part of limited value, since the chemical nature of the types of rubber employed is not described definitely. Then again in most cases little attention was paid to the difference between isothermal and adiabatic stretching. In view of these facts, it seemed desirable to throw further light on the problem by obtaining stress-strain curves of one particular well-defined material. The object of the present work was then: 1. To obtain true isothermal stress-strain curves as a function of the degree of vulcanization and as a function of the temperature, and thus to study stresses as a function of temperature. 2. To obtain data on the same vulcanizates under adiabatic conditions. 3. To compare the stress-strain results under isothermal conditions with those under adiabatic conditions.

Thermodynamics of Crystallization in High Polymers. VI. Incipient Crystallization in Stretched Vulcanized Rubber

1950 ◽  
Vol 23 (3) ◽  
pp. 576-580 ◽  
Author(s):  
Thomas G. Fox ◽  
Paul J. Flory ◽  
Robert E. Marshall
Keyword(s):  
Theoretical Prediction ◽  
Experimental Determination ◽  
Strain Curve ◽  
Steep Slope ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Hydrostatic Method ◽  
Vulcanized Rubber ◽  
High Polymers

Abstract Experimental determination of the elongation at which crystallization commences in vulcanized rubber has been attempted through measurement of density changes by a hydrostatic method. The critical elongation for incipient crystallization appears to depend on the temperature, in approximate accordance with theoretical prediction. Crystallization sets in at an elongation well below that at which the stress-strain curve assumes a steep slope.

The Stress-Strain Relation of Natural and Synthetic Rubbers

1944 ◽  
Vol 17 (4) ◽  
pp. 826-836
Author(s):  
A. J. Wildschut
Keyword(s):  
Carbon Black ◽  
General Formula ◽  
Stress Axis ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Axes Of Symmetry ◽  
Natural And Synthetic

Abstract It is shown that Hatschek's formula for the stress-elongation curve of rubber—better known as Ariano's formula—does not hold for normally vulcanized rubber. The observation has been made that the stress-elongation curves of natural and synthetic rubbers follow nonrectangular hyperbolae closely and practically up to the point of rupture. The axes of symmetry of these hyperbolae make angles of about 40° with the stress-axis in the case of pure-gum mixtures and about 30° for carbon black mixtures. A general formula has been derived which holds for all the rubbers investigated.

Sign in / Sign up

Export Citation Format

Share Document