SOFT VULCANIZED RUBBER EFFECT OF TEMPERATURE AND OXYGEN PRESSURE ON AGING RATE

1936 ◽  
Vol 28 (8) ◽  
pp. 889-892 ◽  
Author(s):  
J. H. Ingmanson ◽  
A. R. Kemp
Keyword(s):  
Oxygen Pressure ◽  
Effect Of Temperature ◽  
Aging Rate ◽  
Vulcanized Rubber

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 and Pressure on Oxygen Pressure Aging

1943 ◽  
Vol 16 (2) ◽  
pp. 453-465 ◽  
Author(s):  
A. M. Neal ◽  
H. G. Bimmerman ◽  
J. R. Vincent
Keyword(s):  
Temperature Coefficient ◽  
Oxygen Pressure ◽  
The State ◽  
Effect Of Temperature ◽  
Individual Study ◽  
Aging Rate ◽  
Temperature Coefficients ◽  
Pressure Test ◽  
Temperature And Pressure

Abstract An increase in the temperature of the oxygen pressure test from 70° to 80° C greatly increases the rate of aging of rubber vulcanizates. The temperature coefficients of aging rate for the six stocks tested vary between 1.63 and 3.48. The state of cure markedly affects the temperature coefficient of some stocks. It is obvious that no change in the specification from 70° to 80° C should be made without first determining the temperature coefficient of the stock involved. A decrease in the pressure of the oxygen pressure test decreases the rate of aging, but the rate is not proportional to pressure. The relative rates of aging between 0.5 and 300 pounds oxygen pressure for the stocks tested vary between 1.09 and 4.87 for the normal cures, and between 1.50 and 6.74 for the longer cures. The state of cure markedly affects the change in rate of aging with change in pressure. The data show that changes in the pressure of the oxygen pressure test must be accompanied by a revision of all aging specifications, which will involve an individual study of each stock and every cure of each stock, since no correlation between stocks seems to exist for the changes in rate of aging that occur with changes in pressure.

THE EFFECT OF TEMPERATURE ON THE CRITICAL OXYGEN PRESSURE FOR HEART-BEAT FREQUENCY IN EMBRYOS OF ATLANTIC SALMON AND SPECKLED TROUT

1942 ◽  
Vol 20d (1) ◽  
pp. 1-12 ◽  
Author(s):  
Kenneth C. Fisher
Keyword(s):  
Atlantic Salmon ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Critical Pressure ◽  
Beat Frequency ◽  
Heart Beat ◽  
Effect Of Temperature ◽  
Limiting Factor ◽  
Partial Pressure Of Oxygen ◽  
Critical Oxygen

Intact embryos of speckled trout and Atlantic salmon were exposed to solutions of oxygen and nitrogen in distilled water. It was observed that as the partial pressure of oxygen was reduced a pressure was found below which the frequency of the heart-beat was not maintained at the normal level characteristic of higher partial pressures of oxygen. A "critical" partial pressure of oxygen for heart-beat frequency can therefore be said to exist. Data have been obtained from which its value at five different temperatures can be determined. The critical pressures for the two organisms are similar, rising from approximately 3 to 5 mm. of mercury at 1.5 °C. to 40 to 50 mm. of mercury at 20 °C. Possible mechanisms leading to the establishment of a critical oxygen partial pressure are discussed. It seems likely that diffusion is not the limiting factor in these preparations so that the critical pressure, and its temperature coefficient, must be the property of the intracellular respiratory systems concerned. The finding that the logarithm of the critical partial pressure can be represented as a linear function of the reciprocal of the absolute temperature is consistent with this view. Temperature exercises a more pronounced effect on the critical oxygen pressure of the pacemaking process, than it does on the over-all velocity of that process as indicated by the normal frequency of the heart. It is concluded that the critical pressure is a characteristic of the chemical systems in the pace-making cells of the heart.

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.

Effect of Temperature and Oxygen Pressure on Preparation of Bi2Sr2CaCu2OxThin Films by Metalorganic Deposition

1991 ◽  
Vol 30 (Part 2, No. 3B) ◽  
pp. L471-L474 ◽  
Author(s):  
Seiji Yaegashi ◽  
Hirohiko Murakami ◽  
Junya Nishino ◽  
Yuh Shiohara ◽  
Shoji Tanaka
Keyword(s):  
Oxygen Pressure ◽  
Effect Of Temperature ◽  
Metalorganic Deposition

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.

Effect of Temperature and Pressure on Oxygen Pressure Aging

1942 ◽  
Vol 34 (11) ◽  
pp. 1352-1357 ◽  
Author(s):  
A. M. Neal ◽  
H. G. Bimmerman ◽  
J. R. Vincent
Keyword(s):  
Oxygen Pressure ◽  
Effect Of Temperature ◽  
Temperature And Pressure
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