Aging Experiments

Hydro-thermal aging (HTA) is performed in the glassy state by immersion in distilled water at the same temperatures as for thermal aging. % values of 40 °C and 60 °C correspond to 38 mg O2 and 23 mg O2 per liter H2O, respectively. 

The freshly distilled water possesses 10 pS cm conductivity, which increases with time due to leaching of the epoxy sample and of the glass container. Therefore, the water is exchanged at 20 pS cm .  

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Ability to control age, experience, specific deficiencies, and other factors can impact the judgment performance of people who evaluate visual quality ... 

The enhancement of thermal stability as measured by these isothermal aging experiments by the addition of bisbenzocyclobutenes to dienophilic thermosetting monomers has also been observed with bis activated acetylenes and dicyanates. The isothermal weight loss results obtained on a one to one mole... 

Duplicate and triplicate IFT aging curves were obtained at one or two temperatures for most of the interfaces characterized in this study. The replicate IFT data reported in Figures 1,3,4,7,8 and 10-14 show that many IFT aging curves for citrus oil/aqueous phase interfaces differ by a maximum of 1.7mJ/m2. Replicate curves often differ by less than lmJ/m2. Because each IFT aging experiment involved formation and separation of a new complex coacervate and supernatant phase, replicate IFT aging curves measure the combined effect that several factors have on reproducibility. These factors include variability of the complex coacervation procedure, protocol followed for separation of the coacervate and supernatant phases, and the IFT measurement process itself. The variability in solids content of replicate coacervate and supernatant phases shown in Table 1 could contribute to the observed IFT variability. 

For ageing experiments the toluene solution of the grafted polymer was first treated with an excess of triphenyl phosphine (reduction of residual hydroperoxides into alcohols), then suitable amount of the parent polymer was added and co-precipitation was performed into methanol. The polymer blend was vulcanized by adding dicumyl peroxide (5% w)prior precipitation (pressing conditions became 190°C, 190 bar, 5 min). 

Figure 10. Electrochemical anodic aging experiments on a lightly doped SrTi03 wafer. All experiments were performed in 1M NaOH. ((1) virgin SrTiO, (2) anodically aged 21 h at 5 V vs. SCE (3) annealed in air 16 h at 300°C)...

The anodic and cathodic aging experiments were done consecutively. 

Olfactory-induced behavior of many insects is known to vary as a function of age, experience and/or environmental conditions. Investment in different behavioral repertoires can often be directly correlated to different adaptive patterns older, unmated individuals become more prone to react to a sex-pheromone stimulus, mated females become more motivated to respond to odors emanating from a suitable oviposition site and a hungry insect will more readily respond to food associated odours. 

A Thermotron programmable humid oven was employed for the accelerated aging experiments. The temperature of the oven was held steadily at 90 0.2°C throughout this series of experiments. The... 

The ratio of the retention of aromatic and hydroxyl absorptions after extensive acetone extraction was similar for different compound compositions cured during different time intervals. Thus, it was concluded that BHT fragments were not bound via EPDM macroradical phenoxy radical combination reactions, leaving combination via EPDM macroradicals and benzylic radicals as the most likely reaction path. In conclusion, it was stated that about 25% to 30% of the BHT became chemically bound, which was further supported by results of ageing experiments using cured samples that had been extensively extracted. 

The increase of the ESR is linear with the time. The values measured during the aging experiment at 50°C and 2.5 V are aligned on a line whose slope is equal to 7.5 x 10-4 [%/h]. 

With 10 minutes of sub-T annealing at 140 °C, thermal expansivity below T decreased to 4.78 x 10-5 K-. This parameter decreased throughout the 140 °C aging experiment. After 10s minutes of aging, the value decreased to 4.30 x 10 s K-1. The free volume decrease evidently dictates the thermal expansivity in the glassy state during sub-T annealing. 

The determination of a complete Arrhenius relation is a long procedure. Even for quite unstable materials, degradation rates are low as room temperatures are approached, yet room temperature must be approached to minimize the errors of extrapolation. Once the slope of the line is established for a given material, the regression data from one oven-aging experiment can be translated to life at room temperature for other samples. Unfortunately, much of the Arrhenius data at hand for paper does not separate hydrolytic from oxidative degradation. The method will make more reliable predictions when such a separation is made. 

The strength of acetate yarn upon exposure to dry heat (120°C) for 500 hr is reduced by 58%. That of triacetate yarn is reduced by 30% at 130 °C (68). In another publication (73) heat aging experiments indicate that the strength retention of triacetate is greater than cotton, which in turn is greater than nylon. Experimental details, however, are lacking in the aging conditions and the type and form of the fibers. 

In principle, if values of at could be determined n times throughout an accelerated aging experiment in which the empirical rate constant, k, is determined, then n simultaneous equations could be solved to yield the chemical rate constants, kt. However, in practice this is not feasible, and Equation 13 is of little analytical value. Nevertheless, our assumption that the property kinetic constant, k, is related linearly to chemical rate constants is verified. Thus, the apparent linearity of the empirical rate constant, kT in Equation 9, with respect to oxygen and acidity suggests the occurrence of chemical processes that are first order in oxygen and acidity. 

Figure 12 shows results of a thermal-aging experiment. Sheets of Whatman No. 42 filter paper were first exposed to near-UV radiation (BLB fluorescent black lights), after which they were subjected to oven... 

The catalyst deactivation model developed in this paper accounts for the nonsteady-state activity of commercial catalysts measured using accelerated sulfur aging experi-... 

The next contributor to the embryonic science of optics was the Arab mathematician and physicist Alhazen (965-1039), who is sometimes called the greatest scientist of the Middle Ages. Experimenting around the year 1000, he showed that light comes from a source (the Sun) and reflects from an object to the eyes, thus allowing the object to be seen. He also studied mirrors and lenses and further refined the laws of reflection and refraction. 

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