Oxygen Absorption of Vulcanizates. A Means of Evaluating Aging Resistance

1950 ◽  
Vol 23 (2) ◽  
pp. 425-439
Author(s):  
Louis R. Pollack ◽  
Robert E. McElwain ◽  
Paul T. Wagner
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Absorption Measurement ◽  
Oxygen Absorption ◽  
Oxygen Bomb ◽  
Ultimate Elongation ◽  
Synthetic Rubber ◽  
Standard Procedures ◽  
Aging Resistance

Abstract The rates of oxygen absorption of two natural and six synthetic-rubber stocks have been measured. In addition, the course of aging in the oxygen bomb and air oven was followed by means of changes in tensile strength and in ultimate elongation of the same eight stocks. Correlation between rates of oxygen absorption and deterioration of physical properties is close enough to justify substitution of a rapid oxygen absorption measurement for longer standard procedures in evaluating the aging characteristics of rubber stocks.

Volumetric Oxygen-Absorption Test for Rubber Aging

1951 ◽  
Vol 24 (4) ◽  
pp. 981-998
Author(s):  
J. Reid Shelton ◽  
William L. Cox
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Chain Scission ◽  
Rate Of Change ◽  
Oxygen Absorption ◽  
Absorption Test ◽  
Absorption Data ◽  
Direct Function ◽  
Oxygen Bomb ◽  
Early Stages

Abstract A volumetric oxygen-absorption test for aging of rubber has been investigated from the point of view of the effect of cure and the effect of mercapto-benzimidazole on the aging behavior. The test has also been evaluated by comparison with conventional air oven and oxygen bomb aging. A compounded but uncured Hevea black stock is more resistant to oxidation than the vulcanized material, but after a reasonable cure is obtained, further heating produces only a small change in the rate of oxygen absorption. The change in physical properties corresponding to a given amount of oxygen absorbed varies somewhat with time of cure in the initial stages, but after the absorption of 4 or 5 cc. of oxygen per gram of rubber, the changes in most physical properties are a direct function of the amount of oxygen absorbed. Neither time of cure nor the presence or absence of inhibitor has any significant effect on the subsequent rate of change in such properties as tensile strength and ultimate elongation for a given amount of oxygen absorbed. Oven aging data on identical time cures confirm the reported superiority of a combination of mercaptobenzimidazole with a conventional type of anti-oxidant. Oxygen absorption data reveal, however, that mercaptobenzimidazole causes a significant decrease in the rate of oxidation of a Hevea black stock, and thus it clearly functions at least in part as an antioxidant in the usually accepted sense. The deterioration of properties is, in general, proportional to the oxygen absorbed, except in the early stages of oxidation where the mercaptobenzimidazole stocks change somewhat less than the controls for a given amount of oxygen absorbed. When the cures are selected to give comparable initial properties, however, the change in tensile strength of the mercaptobenzimidazole stocks with amount of oxygen absorbed is essentially the same as for the controls, even in the initial stages. These data suggest that the observed protection imparted by mercaptobenzimidazole results from a combination of two factors: (1) the normal antioxidant activity of mercaptobenzimidazole, which reduces the amount of oxygen absorbed; and (2) an effect on the nature of the cure attained when mercaptobenzimidazole is present, such that the absorption of a given amount of oxygen in the early stages is not accompanied by as great a change in properties. Thus, it appears that the deactivating effect may be the result of the effect of this material on the vulcanization process rather than a direct effect on the oxidation process. A comparison of the effect of oxygen absorption, air oven, and oxygen bomb aging methods on changes in physical properties of Hevea black stocks shows that the results obtained by oxygen absorption and air oven methods (both at 100° C) are similar, but that the higher oxygen concentration of the oxygen bomb test (70° C and 300 pounds per square inch) apparently results in a higher proportion of chain scission when compared to cross-linking of the polymer chains.

The Direct Determination of Oxygen in Rubber. The Adaptation of the Ter Meulen Method to Rubber and Its Application to the Study of Aging

1939 ◽  
Vol 12 (2) ◽  
pp. 269-282 ◽  
Author(s):  
H. I. Cramer ◽  
I. J. Sjothun ◽  
L. E. Oneacre
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Direct Determination ◽  
Sulfur Poisoning ◽  
Oxidation Products ◽  
Oxygen Bomb ◽  
Vulcanized Rubber ◽  
Relationship Of ◽  
The Relationship

Abstract The ter Meulen method for the direct determination of oxygen has been adapted, with modifications, to the analysis of raw and vulcanized rubbers. Raney nickel has been found to be quite effective as the reducing catalyst and to be satisfactorily resistant to sulfur poisoning. The method has been applied to the study of the aging of vulcanized rubber in the Geer oven and oxygen bomb. From this study the following conclusions may be drawn: (1) The increase in combined oxygen is greater in the oxygen bomb than in the Geer oven. (2) Deterioration of rubber in the oxygen bomb involves oxidation primarily, whereas that occurring in the Geer oven involves not only oxidation but also thermal decomposition followed by volatilization of oxidation products. (3) The effectiveness of an antioxidant in retarding the absorption of oxygen in oxygen-bomb aging agrees well with its ability to maintain the physical properties of the stock in which it is present. (4) The deterioration in physical properties of a rubber stock in the oxygen bomb during the early stages of aging is a linear function of the increase in combined oxygen. For stocks containing antioxidants and diphenylguanidine as the accelerator, an increase in combined oxygen of approximately 1.2% corresponds to a decrease in tensile strength of 50%. (5) The relationship of increase in combined oxygen to decrease in tensile strength seems to be affected not only by antioxidants, but also by accelerators of vulcanization.

A Manometric Test for Oxygen Absorption by Vulcanized Rubber

1942 ◽  
Vol 15 (1) ◽  
pp. 83-90
Author(s):  
Robert H. Johnson
Keyword(s):  
Tensile Strength ◽  
Oxygen Absorption ◽  
Aging Behavior ◽  
Strength Deterioration ◽  
Oxygen Bomb ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Manometric Method ◽  
Set Up ◽  
Bomb Method

Abstract An apparatus can be set up in laboratory glassware that will confirm the results obtained by Dufraisse in his manometric test for oxygen absorption. It has been shown that different rubber compounds possess different tendencies to absorb oxygen. It has also been shown that the differences in the rate at which rubber compounds absorb oxygen are comparable with those differences found in the rate of tensile-strength deterioration of the same compounds aged in the oxygen bomb. This modified Dufraisse manometric method is convenient, efficient, accurate and, above all, a speedy method for measuring the relative aging behavior of vulcanized rubber compounds. Within two hours it is possible to have the results by this method, whereas it is necessary to wait from four days to two weeks for such information by the oxygen bomb method.

Aging of Mechanical Rubber Goods Stocks by Various Methods

1930 ◽  
Vol 3 (1) ◽  
pp. 157-163
Author(s):  
K. J. Soule
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Natural Aging ◽  
Percentage Increase ◽  
Oxygen Bomb ◽  
The Times

Abstract THIS paper records the aging of thirty typical mechanical rubber goods stocks, all of which are, or have been, in regular factory use over long periods of time. The times of aging used are 1 year of natural aging in the dark; 24 hours and 48 hours in the oxygen bomb at 60° C. and 300 pounds (21 kg. per sq. cm.) pressure; and 96 hours at 70° C. in the Geer oven. These stocks are arranged in three groups: (1) lightly compounded, three stocks; (2) medium compounded, twenty stocks; and (3) heavily compounded, seven stocks. The physical properties studied are tensile strength, elongation, tensile product, and modulus. The percentage increase or decrease in each of these properties after each type of aging is recorded. (Tables I to III) Figures 1 to 6, inclusive, show graphically the changes in the physical properties studied on each of the three lightly compounded stocks, using several different methods of presenting the data.

Influence of Sulfur on Stability and Physical Properties of Peroxide Vulcanized Ethylene Propylene Copolymers

1968 ◽  
Vol 41 (2) ◽  
pp. 304-315 ◽  
Author(s):  
J. R. Dunn
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Sulfur Content ◽  
Antioxidant Effect ◽  
Reaction Products ◽  
Ethylene Propylene ◽  
Breaking Elongation ◽  
Ultimate Elongation ◽  
Ethylene Propylene Rubber ◽  
Second Peak

Abstract In cumyl peroxide sulfur vulcanizates of ethylene propylene copolymers crosslinked with 4 phr of peroxide, polysulfidic crosslinks are present only at sulfur levels in excess of 0.5 phr in gum vulcanizates and 0.3 phr in black filled vulcanizates. Modulus attains a peak in the presence of 0.5 phr of sulfur in gum vulcanizates and 0.3 phr of sulfur in black filled vulcanizates. Modulus decreases when polysulfides are present. Tensile strength in gum vulcanizates increases continually with increasing sulfur content up to 2.5 phr. The increase in tensile strength is related to a rapid increase in ultimate elongation, promoted by mechanically labile polysulfidic crosslinks. Tensile strength in black filled vulcanizates exhibits peaks at 0.3 and 0.75 phr of sulfur. The first peak represents the technological recipe for this type of vulcanizate and arises from a peak in modulus. The second peak arises from increased breaking elongation promoted by polysulfidic crosslinks. Sulfides present in the vulcanizate act as antioxidants at all sulfur levels. When the sulfides contain one or two sulfur atoms, the antioxidant effect is mild but long lived. The polysulfides yield potent long lived antioxidants. The rapid nonoxidative degradation of the polysulfidic crosslinks is not accelerated by dithiocarbamate and proceeds after the reaction products have been removed by extraction. Dithiocarbamates are potent antioxidants in peroxide vulcanized ethylene propylene rubber both in the presence and in the absence of sulfur.

DURIMPHY

Alloy Digest ◽  
2007 ◽  
Vol 56 (2) ◽  
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
Yield Strength ◽  
Physical Properties ◽  
Precipitation Hardening ◽  
Heat Treating ◽  
High Yield ◽  
High Yield Strength ◽  
Precision Alloys ◽  
Very High

Abstract Durimphy is a maraging steel with 1724 MPa (250 ksi) tensile strength and a very high yield strength due to precipitation hardening. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: FE-140. Producer or source: Metalimphy Precision Alloys.

CENTRI-CAST GRAY IRON 50

Alloy Digest ◽  
1981 ◽  
Vol 30 (8) ◽  
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Physical Properties ◽  
Machine Tools ◽  
Heat Treating ◽  
Gray Iron ◽  
Centrifugally Cast ◽  
Wide Range ◽  
Nominal Tensile Strength ◽  
Cast Gray Iron

Abstract CENTRI-CAST GRAY IRON 50 is a centrifugally cast gray iron with a nominal tensile strength of 50,000 psi. It is cast in the form of tubing which has a wide range of uses in applications where size and shape are of paramount importance and freedom from pattern cost is an important consideration. Among its many applications are farm machinery, seals, bushings, machine tools and general machinery uses. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, and surface treatment. Filing Code: CI-51. Producer or source: Federal Bronze Products Inc..

CENTRI-CAST GRAY IRON 55

Alloy Digest ◽  
1979 ◽  
Vol 28 (9) ◽  
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Physical Properties ◽  
Surface Treatment ◽  
Heat Treating ◽  
Gray Iron ◽  
Centrifugally Cast ◽  
Wide Range ◽  
Nominal Tensile Strength ◽  
Cast Gray Iron

Abstract CENTRI-CAST GRAY IRON 55 is a centrifugally cast gray iron with a nominal tensile strength of 55,000 psi. It is produced in the form of tubing which has a wide range of uses in applications where size and shape are of paramount importance and freedom from pattern cost is an important consideration. Typical applications are seals, bushings, farm machinery, casings and general machinery uses. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, and surface treatment. Filing Code: CI-48. Producer or source: Federal Bronze Products Inc..

WIELAND-FX9

Alloy Digest ◽  
2011 ◽  
Vol 60 (8) ◽  
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Cold Work ◽  
Heat Treating ◽  
High Manganese ◽  
Bronze Alloy ◽  
Good Strength

Abstract Wieland-FX9 is a high-manganese bronze alloy that has good strength and is available in numerous cold work tempers related to its minimum tensile strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Cu-801. Producer or source: Wieland Metals Inc..

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