Effect of Oxygen Concentration on Aging of Rubber Vulcanizates - Effect of Partial Pressure of Oxygen on Changes in Physical Properties Accompanying Oxidation

1953 ◽  
Vol 45 (2) ◽  
pp. 397-401
Author(s):  
William L. Cox
Keyword(s):  
Physical Properties ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Partial Pressure Of Oxygen ◽  
Effect Of Oxygen

Effect of Oxygen Concentration on Aging of Rubber Vulcanizates. II. Effect of Partial Pressure of Oxygen on Changes in Physical Properties Accompanying Oxidation

1953 ◽  
Vol 26 (3) ◽  
pp. 643-654 ◽  
Author(s):  
J. Reid Shelton ◽  
William L. Cox
Keyword(s):  
Physical Properties ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Chain Scission ◽  
Cross Linking ◽  
Partial Pressure Of Oxygen ◽  
Aging Behavior ◽  
Storage Temperatures ◽  
Normal Storage ◽  
Oxygen Concentrations

Abstract The over-all rate of deterioration of physical properties increases with the oxygen concentration, as would be expected from the increased rate of oxygen absorption: The nature of the deterioration resulting from a given amount of oxygen absorbed is influenced also by changes in the partial pressure of oxygen in the aging atmosphere. It appears that chain scission is favored at higher oxygen concentrations, while cross-linking becomes of greater relative importance at lower oxygen concentrations. These data suggest that R⋅ radicals are more effective than RO2⋅ radicals in reacting with double bonds to form crosslinks. Heat aging in the absence of oxygen, as observed by heating a vulcanizate in lamp-grade nitrogen, results in considerable stiffening, particularly in the case of a GR-S black stock. This effect is observed primarily in the first few hours of heating, and may account for some of the erratic behavior observed in the early stages of aging when changes in physical properties are compared on the basis of amount of oxygen absorbed. Higher oxygen concentration brings about a more rapid oxidation, and also results in a higher proportion of chain scission compared to cross-linking for a given amount of oxygen absorbed. As tensile decay is the most evident sign of deterioration of Hevea stocks, it follows that the aging behavior of natural rubber in air at normal storage temperatures will be better than that predicted by high temperature testing in oxygen. In the case of GR-S stocks, on the other hand, oxidative hardening is the most serious result of aging, and consequently, the aging behavior of GR-S stocks in air at normal storage temperatures is poorer than would be expected on the basis of comparative tests in oxygen at higher temperatures.

Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems

2008 ◽  
Author(s):  
Julian K. Benz ◽  
J. H. Kim ◽  
Ronald G. Ballinger
Keyword(s):  
Growth Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Crack Growth ◽  
Oxygen Concentration ◽  
Crack Path ◽  
Fatigue Loading ◽  
Effect Of Oxygen ◽  
Static Conditions

The effect of oxygen partial pressure on fatigue and SCC growth rates in alloy 617 has been studied using both static and fatigue loading @ 650°C over the oxygen partial pressure range 10−19–10−2 atm. Tests were conducted at either constant stress intensity factor, K, for static conditions or constant ΔK in fatigue. Oxygen concentration was measured on both the inlet and outlet as well as in-situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular and exhibited an increasing crack growth rate with decreasing oxygen concentration.

Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Julian K. Benz ◽  
Ji Hyun Kim ◽  
Ronald G. Ballinger
Keyword(s):  
Growth Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Crack Growth ◽  
Oxygen Concentration ◽  
Crack Path ◽  
Fatigue Loading ◽  
Effect Of Oxygen ◽  
Static Conditions

The effect of oxygen partial pressure on crack growth rates in Alloy 617 has been studied using both static and fatigue loadings at 650°C over the oxygen partial pressure range 10−19−10−3 atm. Tests were conducted at either the constant stress intensity factor K for static conditions or the constant ΔK in fatigue. Oxygen concentration was measured on both the inlet and outlet of the test retort as well as in situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular at the same Kmax (fatigue) and exhibited what appears to be an increasing crack growth rate with decreasing oxygen concentration.

A high temperature, pressure study of the comparative rates of enolization and oxidation of acetone in aqueous solution

1986 ◽  
Vol 64 (11) ◽  
pp. 2235-2237 ◽  
Author(s):  
John W. Thomas ◽  
Jay E. Taylor
Keyword(s):  
Aqueous Solution ◽  
High Temperature ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Total Pressure ◽  
Room Temperature ◽  
Isotopic Exchange ◽  
Partial Pressure Of Oxygen

The rate of enolization and acetone has been determined as 6.6 × 10−4 s−1 at 193.5 °C under nitrogen at 136 atm total pressure via isotopic exchange. The rate of oxidation was determined to be 8.8 × 10−6 s−1 at 193.5 °C in 123 atm partial pressure of oxygen (136 atm total pressure). In a previous study it was shown that the rates of oxidation of several ketones correlated with the extents of enolization at room temperature. This prompted the suggestion that the enol is an intermediate in the oxidation. Since the rate of enolization exceeded the rate of oxidation by a factor of 75, this suggestion is further supported. A dependence of the rate of oxidation of acetone on oxygen concentration was also demonstrated.

ARTIFICIAL HYPOBIOSIS AS A METHOD TO MITIGATE THE NEGATIVE EFFECT OF OXYGEN AT AN ELEVATED PARTIAL PRESSURE

2021 ◽  
Vol 55 (5) ◽  
pp. 64-68
Author(s):  
A.F. Makarov ◽  
◽  
M.A. Kotsky ◽  
А.А. Ton'shin ◽  
I.V. Bukhtiyarov ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Gas Pressure ◽  
Pressure Reduction ◽  
Partial Pressure Of Oxygen ◽  
High Partial Pressure ◽  
Artificial Hypobiosis ◽  
Negative Effect ◽  
Effect Of Oxygen

To assess how hypobiosis modifies the negative effect of a high partial pressure of oxygen, goldhamsters were put into artificial hypobiosis followed by a simulated O2 poisoning at absolute gas pressure of 7 kgf/cm2. The experiment showed an increase in 1.4 times (p = 0.0579) of the period preceding convulsions; reduction in 3.7 times (p = 0.0009) of the period of stabilization on return to normal O2 pressure, reduction of the total convulsions period in 2.3 times (p = 0.0003).

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