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.

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.

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.

Oxidation of Two Isomeric Elastomers: Poly(Propylene Oxide) and Poly(Vinyl Methyl Ether)

1966 ◽  
Vol 39 (2) ◽  
pp. 278-286 ◽  
Author(s):  
Parry M. Norling ◽  
Arthur V. Tobolsky
Keyword(s):  
Methyl Ether ◽  
Propylene Oxide ◽  
Solid Phase ◽  
Chain Scission ◽  
Oxygen Absorption ◽  
Vinyl Methyl ◽  
Absorption Data ◽  
Vinyl Methyl Ether ◽  
Poly Propylene ◽  
Reaction Chain

Abstract Rates of oxygen absorption and chain scission have been measured for benzoyl peroxide initiated oxidation of the two isomeric hydrocarbons, poly(propylene oxide) and poly (vinyl methyl ether) in the temperature range 80–100° C and in the solid phase. Oxygen absorption data show that poly(propylene oxide) forms hydroperoxides 3.5 times as fast as poly (vinyl methyl ether). This may be attributed to steric hindrance in the propagation reaction. Chain scission, measured by stress relaxation of crosslinked samples, demonstrates that each initiating radical produces one scission in the poly(propylene oxide). The process appears to be less efficient in the poly(vinyl methyl ether). Two possible reactions are proposed to explain this observation.

Relationships between Chemical Structures of Crosslink Sites and Physical Properties of Vulcanized Rubbers. Part VI. Oxidative Degradation of EPDM Vulcanizates

1970 ◽  
Vol 43 (2) ◽  
pp. 431-444 ◽  
Author(s):  
M. Imoto ◽  
Y. Minoura ◽  
K. Goto ◽  
H. Harada ◽  
K. Nishihira ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Physical Properties ◽  
Oxidative Degradation ◽  
Oxygen Absorption ◽  
Chemical Structures ◽  
Early Stages ◽  
Absorption Measurements

Abstract Relationship between the chemical structures of crosslinks and the degree of oxidative degradation of EPDM vulcanizates was studied by stress relaxation and oxygen absorption measurements. It was found that the vulcanizates having C—Sx—C crosslink showed slower stress relaxation than the vulcanizate having other crosslink structures, i.e., C—S—C, C—C, and C—R—C. It was thought that C—Sx—C bond would reduce the scission of the network in oxidative degradation, since some polysulfide compounds had the same effect of protecting scission as antioxidant. The similar results were obtained in oxygen absorption measurements. In the case of heat aging, the vulcanizate having C—Sx—C linkage increased in crosslinks during aging and the rate of crosslinking was equal to the rate of scission of the network in the early stages, but the vulcanizates having other types of crosslinks did not show such behavior.

Aging of GR-S Vulcanizates in Air, Oxygen, and Nitrogen

1945 ◽  
Vol 18 (1) ◽  
pp. 116-121
Author(s):  
J. Reid Shelton ◽  
Hugh Winn
Keyword(s):  
Tensile Strength ◽  
Chain Scission ◽  
Oxygen Bomb ◽  
Cross Linkage

Abstract The results of aging GR-S vulcanizates in air, oxygen, and nitrogen show: 1. The decrease in tensile strength observed in both bomb and oven aging is caused by the action of oxygen. 2. The modulus increase obtained in the oxygen bomb at 80° C is not caused by oxygen in the aging atmosphere. 3. At 100° C in air, more than half of the hardening, measured by the modulus increase obtained after five days, may be attributed to the action of oxygen. It therefore appears that oxygen acts on GR-S vulcanizates in two distinctly different ways: 1. A reaction leading to tensile breakdown, which no doubt involves chain scission. This reaction takes place at both 80° and 100° C, and is effectively retarded by the antioxidant, phenyl-β-naphthylamine. 2. A reaction producing a stiffening of the GR-S, as shown by the modulus increase. This stiffening suggests the formation of polymeric products—for example, by cross-linkage. This reaction was not observed at 80° C, but was a major factor in the aging at 100°, and was little affected by the antioxidant employed.

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.

Effect of Temperature on Rate of Oxidation of Rubber. Nature of Resultant Deterioration

1954 ◽  
Vol 27 (1) ◽  
pp. 120-133 ◽  
Author(s):  
J. Reid Shelton ◽  
Fred J. Wherley ◽  
William L. Cox
Keyword(s):  
Quantitative Measure ◽  
Chain Scission ◽  
Absolute Temperature ◽  
Rate Of Change ◽  
Effect Of Temperature ◽  
Oxygen Absorption ◽  
Short Term ◽  
Degradation Reactions ◽  
Lower Temperature ◽  
Time Required

Abstract The same reaction appears to be rate-controlling in the oxidation of natural rubber and GR-S stocks at all temperatures in the range studied, 50° to 110° C. This is apparent from the linear relationship established between rate of oxygen absorption and the reciprocal of the absolute temperature. Presumably this would also be true for a reasonable extrapolation to lower or higher temperatures. Thus it is possible to determine the probable rate of oxygen absorption at room temperature on the basis of data obtained in short-term tests at higher temperatures, provided data are available at several temperatures. The effect on properties which accompanies the absorption of a given amount of oxygen varies with the temperature. For example, aging at higher temperatures produces a softer stock with lower modulus and higher elongation than is obtained by the absorption of the same amount of oxygen at a lower temperature. Thus chain scission predominates at higher temperatures, while cross-linking becomes of greater relative importance at lower temperatures. These facts, together with the observation that the same reaction is rate-controlling at all temperatures studied, indicate that the degradation reactions must be secondary reactions which are not rate-controlling. One cannot predict the aging characteristics of a stock by the use of an accelerated test at only one temperature. It is possible, however, to establish a quantitative measure of the rate of change in a given property (per unit amount of oxygen absorbed) as a function of temperature by means of tests at more than one temperature. Thus it is now possible to utilize short-term oxygen-absorption measurements at, say, three temperatures to establish the relationships, and then to extrapolate the data to lower temperatures and predict the time required to absorb a given amount of oxygen and the degradation of properties to be expected under comparable conditions at the lower temperature. If a change from oxygen to air is also involved, the effect of the changes in oxygen concentration must also be taken into account.

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.

Oxidation of GR-S and Other Elastomers

1947 ◽  
Vol 20 (3) ◽  
pp. 747-759
Author(s):  
John O. Cole ◽  
James E. Field
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Physical Properties ◽  
Experimental Methods ◽  
Chain Scission ◽  
Cross Linking ◽  
Antioxidant Action ◽  
Mechanism Of Oxidation ◽  
Natural Rubber Vulcanizates

Abstract The effect of heat aging on the physical properties of an elastomer is generally considered the result of oxidation, which produces both chain scission and cross-linking in the polymer. Early in the development of GR-S, a marked difference in the aging of GR-S and natural rubber vulcanizates was observed. From the effect of aging on hardness, tensile strength, modulus, and elongation it appeared that cross-linking occurred more rapidly than chain scission with GR-S, but the reverse was true with natural rubber. The work reported here was undertaken to provide a better understanding of the differences in aging of GR-S and natural rubber and to introduce new experimental methods for studying the mechanism of oxidation and antioxidant action in elastomers.

scholarly journals MECHANICAL AND PHYSICAL PROPERTIES OF THERMOPLASTIC CORN STARCH

2021 ◽  
Vol 83 (5) ◽  
pp. 119-127
Author(s):  
Nazri Huzaimi Zakaria ◽  
Ridhwan Jumaidin ◽  
Mohd Adrinata Shaharuzaman ◽  
Mohd Rody Mohamad Zin ◽  
Fudhail Abdul Munir
Keyword(s):  
Tensile Strength ◽  
Moisture Content ◽  
Physical Properties ◽  
Water Absorption ◽  
Corn Starch ◽  
Absorption Test ◽  
Physical Test ◽  
Biodegradable Composite ◽  
Mechanical And Physical Properties ◽  
Water Absorption Test

The awareness to produce biodegradable composite has increased rapidly because of non-toxic and reachable. However, fully biodegradable composite production still low due to the matrix used in the composite is not biodegradable. Thus, this paper presents the study on mechanical and physical properties for the mixtures of corn starch (CS) with different weight percentages of glycerol as thermoplastics corn starch (TPCS) matrix. The selected glycerol contents were at 30, 35 and 40 wt%. The mixtures of CS and different weight percentages of glycerol were made using hot compression moulding at 165°C for 15 minutes to produce the TPCS samples. The mechanical and physical properties were done: the tensile test, hardness test, water absorption test, moisture content test and microstructure analysis under the Scanning Electron Microscopes (SEM). Incorporating 30 wt% loadings of glycerol has increased the tensile strength and hardness. The results show that the addition of higher than 30 wt% loadings of glycerol has decreased the tensile strength and hardness of the TPCS. The physical test results for 30 wt% loadings of glycerol for water absorption test and moisture content show the lowest value than other TPCS samples. However, the density value for all wt% loadings of glycerol does not offer much difference. It reveals that 30 wt% loadings of glycerol in the mixture of CS have shown a good interaction in the TPCS mechanical properties. Based on this finding, the TPCS has huge potential to be used as a matrix to develop a fully biodegradable composite.

Sign in / Sign up

Export Citation Format

Share Document