Oxygen Aging Process

Types of aging processes such as those described for the adsorption of oxygen and methanol on platinum are also characteristic of the adsorption of other substances and of adsorption on other electrodes. In some cases these changes manifest themselves as a change (mostly an increase) in the adsorption energy with time. In... 

For a ToF-SIMS investigation of the surface oxidative degradation of low-density polyethylene (LDPE), the polymer was exposed to 1802 rather than 1602 in order to be able to readily discriminate oxygen introduced by the ageing process from that in the polymer prior to ageing [102], Figure 36 shows an example series of ToF-SIMS spectra from this investigation, which shows the clear separation of the lsO species from the lsO species. In the study, close correlation was observed between the intensity of the lsO carbonyl species determined by mid-infrared spectroscopy with the ToF-SIMS 180- peak intensity as a function of 1802 exposure time. ToF-SIMS spectra obtained from microtomed cross-sections showed no... 

Because oxygen is used up in the ageing process it is important that an air flow is maintained and the test pieces are exposed to air on all sides. With either type of oven, there must be a steady flow of air through the oven. IEC 60216 [2] specifies between 5 and 20 complete changes per hour which means that some general purpose laboratory ovens would not be suitable. The air velocity will also affect the rate of ageing but this is said to be under consideration in IEC 60216-4 [7]. 

Alcohols, carboxylic acids, and esters are oxygen-containing molecules that play multiple roles in living organisms. Oxygen-centered radicals are thought to contribute to the aging process. 

Oxidation is another important factor for the wine-aging process. Major oxidation reactions taking place in wine following oxygen exposure actually involve other wine constituents that are primarily ethanol and, in the presence of metal ions, tartaric acid rather than flavonoids, although phenolic compounds have been shown to participate in oxidation of ethanol to acetaldehyde. ... 

The Arrhenius treatment has been applied to aging studies on rubber (13), to predict the life of a polyester-glass laminate (14), to predict product stability of a thermosetting resin alone and in combination with two additives (15), in permanence tests on paper (16), to multi-component systems in which the principal component is paper (17), and to study the influence of temperature on the relative contributions of the oxygen-independent and oxygen-dependent processes to the total rate of newsprint deterioration (18-20). 

The restrictive conditions of the biological aging process of wine (namely low pH, presence of sulphite, high ethanol and acetaldehyde concentrations, lack of sugars and low oxygen concentration) are compatible with only a few S. cerevisiae races. Also, the presence of specific flor races has been correlated with the aging stage of the wine and the sensory features of the end product (Mesa et al. 2000). 

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