Outgassing, analysis

Extractables, leachables and outgassing analysis from leather, textiles, car interior materials or food... 

Catalytic combustion experiments have been performed in a flow reactor operating below the lower explosion limits using HC/02/He mixtures. The product analysis was done by gas chromatography. FT-IR spectra have been recorded with a Nicolet Magna 750 instrument, using conventional IR cells connected with evacuation-gas manipulation apparatus. The powder was pressed into self-supporting disks, calcined in air at 773 K and outgassed at 773 K for 20 minutes before experiments. 

IMS can be used for chemical analysis of vapours from electronics packaging [287]. IMS-QMS has been used to analyse headspace vapours in sealed electronic packages [275,288] and to follow outgassing of polymers [287]. Various types of photoresist solvents, phtha-late plasticisers and other polymer additives, such as BHT, were detected. Other applications of IMS in semiconductor technology involve failure analysis control of the efficiency of cleaning and etching steps characterisation of process media and surveillance of the atmosphere of clean rooms. 

In one of the earliest reports of the use of clean evaporated alloy films in surface studies, Stephens described the preparation and characterization of Pd-Au films and presented some results for the adsorption of oxygen on them 46). Films of pure Pd and 60% Au were evaporated directly from wires, while films of 80% Au and pure Au were evaporated from a pre-outgassed tungsten support wire. The films were evaporated in a UHV system and the pressure was kept below PC8 Torr during evaporation. After evaporation, the films were stabilized by cycling between —195° and 30°C four times. They w ere characterized by X-ray diffraction and chemical analysis surface areas were measured by the BET method using krypton adsorption. 

Nitrogen adsorption was performed at -196 °C in a Micromeritics ASAP 2010 volumetric instrument. The samples were outgassed at 80 °C prior to the adsorption measurement until a 3.10 3 Torr static vacuum was reached. The surface area was calculated by the Brunauer-Emmett-Teller (BET) method. Micropore volume and external surface area were evaluated by the alpha-S method using a standard isotherm measured on Aerosil 200 fumed silica [8]. Powder X-ray diffraction (XRD) patterns of samples dried at 80 °C were collected at room temperature on a Broker AXS D-8 diffractometer with Cu Ka radiation. Thermogravimetric analysis was carried out in air flow with heating rate 10 °C min"1 up to 900 °C in a Netzsch TG 209 C thermal balance. SEM micrographs were recorded on a Hitachi S4500 microscope. 

Chemical composition of fresh HTs was determined in a Perkin Elmer Mod. OPTIMA 3200 Dual Vision by inductively coupled plasma atomic emission spectrometry (ICP-AES). The crystalline structure of the solids was studied by X-ray diffraction (XRD) using a Siemens D-500 diffractometer equipped with a CuKa radiation source. The average crystal sizes were calculated from the (003) and (110) reflections employing the Debye-Scherrer equation. Textural properties of calcined HTs (at 500°C/4h) were analyzed by N2 adsorption-desorption isotherms on an AUTOSORB-I, prior to analysis the samples were outgassed in vacuum (10 Torr) at 300°C for 5 h. The specific surface areas were calculated by using the Brunauer-... 

In order to avoid contaminating the outgassed sample when transferring from the outgassing to the analysis position, the cells are mounted in spring-loaded self-sealing holders that close when disconnected and open when placed in position. 

Samples of rutile Ti02 were outgassed at elevated temperatures in some instances this was followed by subsequent exposure to 02 at 150°C. The following results were obtained by the BET analysis of N2 adsorption after various preliminary treatments ... 

The differential thermal analysis, thermogravimetric analysis, and x-ray results establish that the cationic modifications are stable under the outgassing conditions used in the sorption measurements. 

Attempts were made to measure the kinetics of adsorption on the other oxides. In the case of MgO, the uptake was very small and very approximate kinetic measurements at pressures of 10-2 mm. and below gave activation energies of the order of 10-15 kcal./mole, whereas with ZnO the uptake was complicated by oxidation of Zn atoms exposed during the outgassing process an approximate analysis gave an activation energy of 15 6 kcal./mole for what appeared to be true chemisorption at low pressures ( 5 mm.) near saturation. 

Post and co-workers [49] have used TG-FTIR to study the outgassing of a plasticiser (type and amount) from an ethylene-propylene-diene terpolymer (EPDM) compound. Figure 1.6 shows the thermogravimetric decomposition behaviour of the EPDM compound. The plasticiser emerges in the first mass-loss step, which was identified as adipic acid diisobutylester by on-line infrared analysis. 

Jansen and co-workers [86] have evaluated temperature-controlled outgassing processes of plastics and rubbers using both off-line and on-line TD-GC-FTIR-MS. Decomposition of polyesterurethanes by means of TG-Tenax off-line sampling followed by TD-GC-FTIR-MS revealed C02, H20, tetrahydrofurane, cyclopentanone, dicarbonic acid, aliphatic diols and esters [86]. The same authors have also described the detection of polychlorinated biphenyls (PCB) in 2,4-dichlorobenzoylperoxide cured silicone rubbers after outgassing products of a rubber silicone part obtained after desorption for 10 minutes at 200 °C in the thermal desorption cold-trap and subsequent analysis by means of TD-GC-MS. Using a mass range of 290-294 Da the MS can be used as a selective detector for these substances. 

Approximately 0.3 g of sample was outgassed at 110°C prior to analysis. Nitrogen adsorption-desorption isotherms were recorded at 77.35 K using a Micromeritics ASAP 2010 adsorption analyzer at p/p0 > 10 6 - 10 5, where p and po denote the equilibrium pressure and saturation pressure of nitrogen at 77.35 K, respectively. 

The samples were outgassed prior to each experiment using Controlled Rate Thermal Analysis or CRTA [2]. A constant pressure of 10 mbar was used for the thermal preparation up to a final temperature of 250°C. 

Surface area measurements of fresh and used catalysts were carried out using a Micromeritics ASAP 2000 apparatus with nitrogen as the adsorbing gas, considering a value of 0.164 nm for the cross-section of the nitrogen molecule. All samples were outgassed at 200 C before analysis. 

Nitrogen sorption at 77 K was performed using an automated Micromeritics Tristar 3000 Surface Area Analyser. The sample was outgassed by purging using the Micromeritics Flowprep 060 at 423 K under nitrogen flow for 6 h prior to analysis. 

The adsorption up to 50 bars was carried out by means of a Tian-Calvet type isothermal microcalorimeter built in the former CNRS Centre for Thermodynamics and Microcalorimetry. For these experiments, around 2 g of sample was used which were outgassed by Controlled Rate Thermal Analysis (CRTA) [7]. The experiments were carried out at 30°C (303 K). Approximately 6 hours is required after introduction of the sample cell into the thermopile for the system to be within 1/100 of a degree Celsius. At this point the baseline recording is taken for 20 minutes. After this thermal equilibrium was attained, a point by point adsorptive dosing procedure was used. Equilibrium was considered attained when the thermal flow measured on adsorption by the calorimeter returned to the base line. For each point the thermal flow and the equilibrium pressure (by means of a 0-70 bar MKS pressure transdueer providing a sensitivity of 0.5% of the measured value) were recorded. The area under the peak in the thermal flow, Q eas, is measured to determine the pseudo-differential... 

XRD patterns were obtained at room temperature, using a Rigaku Model D/MAXIII B (CuKa X-ray source). All samples were scanned under the same conditions (26 = 1.2 -10 ). N2 isotherm was measured by using an ASAP 2400 (Micromeritics) at 77 K. Prior to each analysis, the samples were outgassed at 298 K for 6 h to obtain a residual pressure of less than lO torr. 

Zeitler P. K. (1987) Argon diffusion in partially outgassed alkali feldspars insights from " Ar/ Ar analysis. Isotope Geoset 65, 167-181. 

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