Oxygen uptake atmosphere

Oxygen uptake Atmospheric pressure, 80-100°C, do not represent normal storage... 

In OIT determinations, the test samples are flushed continuously with oxygen during the course of the measurement [1], This is in contrast to oxygen-uptake measurements that are mostly undertaken in a static oxygen atmosphere (see below). Effects such as dynamic removal of volatile antioxidants in the OIT method can lead to these two methods yielding very different assessments of a polymer formulation s stability [1]. 

The oxygen absorber, the reactor, and the connecting tubing were immersed in a constant temperature oil bath whose temperature was controlled within 0.2°C. The oxygen uptake by the coal was recorded, and the pressure in the system was controlled with Swarthout electronic transmitters and recorders. Pressure control was within 10 3 atmospheres, while experiments were made up to 9 atmospheres total pressure. 

Induction Period. The resins were heated in a nitrogen atmosphere to 190°C. and maintained isothermally at 190°C. for five minutes. Nitrogen was then replaced with oxygen, and the time was noted (zero minutes for unstabilized resin) to a significant exotherm. The data are shown and compared with oxygen uptake and U-tube data in Table VI. Resin A, which was least stable in 25-mil plaques at 140° and 150°C., is best by the DTA oxidation exotherm method, while I, which was best in 25-mil plaques at 140° and 150 °C., is next to the poorest material in DTA oxidation exotherm and induction period test methods. Resin C is relatively consistently poor, and H consistently tests high. 

Oxidation reaction. The oxidation reaction was carried out in an oxidation apparatus at room temperature and atmospheric pressure. The mixture was stirred and the oxygen uptake was followed by a pressure transducer. 

Allylic oxidation of cyclohexene. Pd(OAc)2 (22 mg), hydroquinone (44 mg), FePc or CoSp (0,01 mmol) and LiOAc 2H2O (102 mg) were stirred in acetic acid (10 mL) for 20 minutes. The reaction was put under oxygen atmosphere and cyclohexene (0.20 mL) was added fi om a syringe. The reactor was heated to 333 K with a water thermostat, and the oxygen uptake was measured. 

Oxygen uptake experiments were performed at constant pressuref = 1 atmosphere) and constant temp)erature in the TAP-2 microreactor. In a typical flow oxidation a reactor equilibrated catalyst was exposed to a flow of pure oxygen for a period of one hour. Oxidation temperatures ranged from 683 K to 803 K. After a period of one hour, the reactor was evacuated and the temperature was lowered to reaction temperature (653 K). 

Figure 1. Oxygen Uptake of Stabilized and Unstabilized HDPE at 140°C and 1 Atmosphere...

Figure 4. Arrhenius Plot of Stabilized and Unstabilized HDPE During Oxidation, Oxygen Uptake at 1 Atmosphere and Three Temperatures...

The kinetics of oxidation of toluene was studied at atmospheric pressure by measuring oxygen uptake using a glass manometric apparatus. The detailed procedure and experimental setup are described elsewhere [4,8]. 

The respiration activity of the immobilized mycelium was examined by using an oxygen electrode. The rate of oxygen uptake by the immobilized mycelium was about 30 % of that of the washed mycelium. Furthermore, penicillin production by the immobilized mycelium was performed under air and nitrogen atmospheres and the penicillin produced was determined. Only a small amount of penicillin was produced by the immobilized mycelium under anaerobic conditions. Therefore, oxygen was required for the system synthesizing penicillin in mycelium. 

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