Oxidation of Vulcanized Rubber Effect of Temperature, State of Cure, and Thickness

1939 ◽  
Vol 31 (12) ◽  
pp. 1472-1478 ◽  
Author(s):  
A. R. Kemp ◽  
J. H. Ingmanson ◽  
G. S. Mueller
Keyword(s):  
Effect Of Temperature ◽  
Vulcanized Rubber ◽  
Temperature State

Oxidation of Vulcanized Rubber. Effect of Temperature, State of Cure, and Thickness

1940 ◽  
Vol 13 (2) ◽  
pp. 375-388
Author(s):  
A. R. Kemp ◽  
J. H. Ingmanson ◽  
G. S. Mueller
Keyword(s):  
Tensile Strength ◽  
Effect Of Temperature ◽  
Oxygen Requirement ◽  
Tetramethylthiuram Disulfide ◽  
Strength Deterioration ◽  
Vulcanized Rubber ◽  
Hydrocarbon Content ◽  
Straight Line ◽  
Temperature State ◽  
Thickness Variations

Abstract 1. A previous investigation of the rate of oxidation of rubber over the temperature range of 60° to 80° C. has been extended to 90°, 100° and 110° C. 2. The rate of oxidation over the range which accounts for substantial deterioration of tensile strength appears to be a straight-line function of the time of aging from 60° up to an including 90° C. The rate of oxidation at 100° C. appears to diverge somewhat from a straight-line function of time decreasing as oxidation proceeds. 3. The rate of oxidation increases with increased temperature. Over the range of 60° to 110° C, the rate is doubled for each 7.5° increase in temperature, corresponding to a temperature coefficient of oxidation of 2.5. 4. Tensile strength decreases as a straight-line function of the time of aging and of the quantity of oxygen absorbed. 5. The quantity of absorbed oxygen, determined by weight gain corresponding to a 50 per cent decrease in tensile strength, varies with the temperature of oxidation. At 60° C. the oxygen requirement for 50 per cent deterioration is about 1.30 per cent, and at 110° C. about 0.65 per cent on the rubber hydrocarbon content. 6. Tensile strength increases, probably due to a mild curing effect, when specimens of the compound are heated in an atmosphere where the oxygen is replaced with carbon dioxide for the same periods of time at 80° and 110° C, were required to cause a 50 per cent deterioration in tensile strength in an oxygen atmosphere. 7. With increased time of vulcanization, the rate of oxidation increases. Oxidation appears to be autocatalytic in the case of overvulcanized rubber. 8. As time of vulcanization increases, there is a decrease in the quantity of oxygen required to cause a given decrease in tensile strength. 9. Thickness variations of 0.43 to 1.90 mm. in test-specimens of a compound containing an antioxidant do not affect quantity of oxygen absorbed or degree of tensile strength deterioration when aging is conducted at 80° C. and 3.5 kg. per sq. cm. oxygen pressure. 10. When tetramethylthiuram disulfide is used for vulcanization in place of sulfur, there appears to be no change in the mechanism of oxidation, but the rate of oxidation is reduced.

Soft Vulcanized Rubber. Effect of Temperature and Oxygen Pressure on Aging Rate

1937 ◽  
Vol 10 (2) ◽  
pp. 336-345
Author(s):  
J. H. Ingmanson ◽  
A. R. Kemp
Keyword(s):  
Oxygen Pressure ◽  
Mechanical Strain ◽  
Accelerated Aging ◽  
Effect Of Temperature ◽  
Aging Rate ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Cause Of Failure ◽  
Service Conditions ◽  
Oxidation Effect

Abstract IMPORTANT to the manufacturer and consumer of rubber goods are suitable accelerated aging tests for predicting readily the life of rubber articles under the variable storage and service conditions encountered. Since service conditions may involve the exposure of rubber to wide variations of temperature, light, and atmosphere under various types of mechanical strain, there is obviously need for a variety of tests, each designed to emphasize factors which are most important in any given set of service conditions. Since the primary cause of failure of soft vulcanized rubber in service is oxidation, emphasis has been placed on tests which accelerate the oxidation effect. The most widely adopted and generally satisfactory procedure of this type is the Bierer and Davis oxygen bomb method which involves heating the rubber under oxygen pressure. In Bierer and Davis' original publication (2), results were shown on the effect of increasing oxygen pressure in increments of 28.1 kg. up to 112.5 kg. per cm. on the aging of two different rubber compounds at the three temperatures, 50°, 60°, and 70° C. Their results showed that in some cases there was a uniform increase in aging rate with increased pressure and in other cases the rate increased rapidly up to a pressure of 28.7 kg. per sq. cm. but more slowly with further increases in pressure. In a later investigation (3) the same authors employed a pressure of 21.1 kg. per sq. cm. and 60° C. throughout. For the past ten years most laboratories have used an oxygen pressure of 21.1 kg. per sq. cm. and a temperature of 70° C., which may therefore be considered as standard.

Effect of Temperature on Tensile Properties of Vulcanized Rubber

1934 ◽  
Vol 7 (2) ◽  
pp. 371-386
Author(s):  
A. A. Somerville ◽  
W. F. Russell
Keyword(s):  
High Temperature ◽  
Tensile Properties ◽  
Room Temperature ◽  
Point Of View ◽  
Effect Of Temperature ◽  
Curing Conditions ◽  
Vulcanized Rubber ◽  
Before And After ◽  
Temperature Test ◽  
Better Than

Abstract The tensile properties and tear resistance of a large number of commercial inner tubes, before and after aging by different methods, are studied at 0°, 25°, and 100° C. A number of uncured bus-truck tube stocks are also studied from the point of view of their capacity to withstand high temperatures. The effect of testing rubber at 100° C. as compared with room temperature is discussed; how some compounds collapse at 100° C., while others have tensile properties equal to, or better than those at 25°, is shown. The effect of testing artificially aged specimens at 100° C., as well as at 25° C., is discussed; the high-temperature test may reveal conditions of deterioration and overcure that are not noticeable in the 25° tests. The compounding and curing conditions that lead to high tensile properties at 100° C., as well as those which cause inferior quality, are discussed.

Crystallization of Unvulcanized Rubber at Different Temperatures

1946 ◽  
Vol 19 (4) ◽  
pp. 1145-1162 ◽  
Author(s):  
Lawrence A. Wood ◽  
Norman Bekkedahl
Keyword(s):  
Quantitative Data ◽  
Effect Of Temperature ◽  
X Ray Diffraction ◽  
General Study ◽  
Volume Changes ◽  
Experimental Conditions ◽  
X Ray ◽  
Vulcanized Rubber ◽  
Different Temperatures ◽  
Comprehensive Study

Abstract Crystals may be formed in natural rubber under varied experimental conditions. Different combinations of stretching and cooling have been used to induce crystallization in unvulcanized and in vulcanized rubber. The appearance and disappearance of crystals have been studied by observations of the volume, heat capacity, light absorption, birefringence, x-ray diffraction, hardness, and other mechanical properties. There has, however, been no comprehensive study of the effect of temperature on the crystallization. The present investigation was undertaken to explore this field. In the work reported here it has been the aim to study crystallization at different temperatures under the simplest possible conditions. The main features of the crystallization of vulcanized rubber have been shown to be similar to those of the crystallization of unvulcanized rubber, vulcanization decreasing the rate of crystallization. Consequently unvulcanized rubber was selected for study. Stretching obviously complicates the experimental conditions, and so was not employed. Of the different methods of measuring crystallization, it seems that change of volume is the simplest and best adapted to yielding quantitative data on the course of the crystallization or fusion. The present work is, therefore, concerned with a general study of the volume changes in unvulcanized rubber at different temperatures.

Chain Scission in the Oxidation of Hevea. III. Effect of Temperature

1956 ◽  
Vol 29 (4) ◽  
pp. 1274-1275
Author(s):  
E. M. Bevilacqua
Keyword(s):  
High Efficiency ◽  
Hydrocarbon Chain ◽  
Chain Scission ◽  
Solution Viscosity ◽  
Effect Of Temperature ◽  
Volatile Acid ◽  
Vulcanized Rubber ◽  
Complete Destruction ◽  
End Groups ◽  
Oxygen Requirements

Abstract When molecular oxygen reacts with raw Hevea rubber in latex at 90° C, two molecules of carbon dioxide and two molecules of “volatile acid” (one molecule of acetic acid and one molecule of formic acid) are produced for each apparent scission of the hydrocarbon chain, estimated from changes of solution viscosity. This corresponds to the complete destruction of one isoprene unit, and if the several hydrocarbon end groups are oxidized, requires a minimum of six molecules of oxygen per scission. Estimates of oxygen requirements for scission during the accelerated oxidation of vulcanized Hevea rubber much lower than this have been made. It has been suggested that the apparent high efficiency of scission in vulcanized rubber is the result of the predominance of scission at crosslinks over random cutting of the hydrocarbon chain. To investigate the less likely possibility that the mechanism of the reactions which leads to scission changes sharply with the rate of oxidation, the earlier estimates of yields of scissions and of volatile acids during the oxidation of Hevea latex at 90° C have been supplemented by measurements at 70° C and at 110° C.

The Effect of Temperature on the Stress-Strain Properties of Vulcanized Rubber

1929 ◽  
Vol 2 (1) ◽  
pp. 1-20
Author(s):  
A. A. Somerville ◽  
W. H. Cope
Keyword(s):  
Testing Machine ◽  
The State ◽  
Effect Of Temperature ◽  
Stress Strain ◽  
Lower Strength ◽  
Vulcanized Rubber ◽  
Different Temperatures ◽  
Strain Relationship ◽  
Commercial Testing

Abstract A method has been devised for testing rubber at various temperatures by putting a simple attachment onto a commercial testing machine. Wide variations have been found in the stress-strain curves on the same stock at different temperatures. The stress-strain properties at different temperatures vary for different rubbers. The state of cure causes a wide variation in tests at various temperatures. The amount of sulphur used is a factor in the stress-strain relationship at different temperatures. Successive stresses on the same piece of rubber show large decreases after the first or second stress. Stripping tests on frictions show much lower strength at 100° C. than at 0° C. Overcures are indicated prominently when stocks are tested at 100° C. Artificially aged rubber tested under these conditions shows a very marked deterioration which may be offset by anti-oxidants.

Effect of Temperature on Tensile Properties of Vulcanized Rubber

1933 ◽  
Vol 25 (10) ◽  
pp. 1096-1101 ◽  
Author(s):  
A. A. Somerville ◽  
W. F. Russell
Keyword(s):  
Tensile Properties ◽  
Effect Of Temperature ◽  
Vulcanized Rubber

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

The effect of temperature on high-resolution TEM image contrast

1995 ◽  
Vol 53 ◽  
pp. 640-641
Author(s):  
T. Geipel ◽  
W. Mader ◽  
P. Pirouz
Keyword(s):  
Form Factor ◽  
Inelastic Scattering ◽  
Accurate Method ◽  
Waller Factor ◽  
Effect Of Temperature ◽  
Specimen Thickness ◽  
Influence Of Temperature ◽  
Debye Waller Factor ◽  
Influence Of Temperature On ◽  
Atomic Form Factor

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).

Sign in / Sign up

Export Citation Format

Share Document