Mettler studies

Since the early 1970s, studies on small-scale batch and semi-batch reactors have been carried out in the industrialized community. These studies resulted, in some cases, in the development of commercially available bench-scale reactors (BSR), such as the RC1 from Mettler-Toledo [184], and the Contalab... 

In a similar evaporative loss study, a defined volume of distilled water was placed in reagent vials that were weighed on a Mettler balance and placed in the reagent carousel. The instrument s lid was kept closed, and at intervals, the measurements were repeated. During the test, the temperature within the machine averaged 25 °C, and the humidity was 28%. After 2 h, the reagent vials had lost 6% of their original volume. 

Figu re 4.9 Thermogram obtained in a reaction calorimeter (Mettler-Toledo RC1) during the study of a catalytic hydrogenation. The heat release rate suddenly increases after 3 hours, which indicates a complex reaction scheme involving several steps in series. The second sharp peak after 5.8 hours is due to... 

Several companies supply density equipment which was considered suitable for automatic, continuous operation with sufficient precision for calculation of polymerization conversion. These break down into three classes based on mode of operation y-ray absorption, oscillatory frequency of a sample filled tube, and mass measurement at fixed volume. Only one of these, an oscillator-based system distributed by Mettler Instrument Corp. (representing Anton Paar Ag.) has models with dead volumes small enough for laboratory scale experimentation. The other units generally also suffered from narrow density spans when the precision was sufficient for conversion studies. Table... 

Materials and Processing. Copolyesters of poly(ethylene terephtha-late) (PET) and para-oxybenzoic acid (FOB) were supplied by the Tennessee Eastman Corporation. Past work Indicates the copolyesters form thermotropic liquid crystalline phases at compositions containing more than 30 mole% POB (26,27,28). The composition of the copolyester studied here contains 60 mole% POB. Quiescent liquid crystalline films were made by compression molding the copolyester at 210, 230, 255, and 285 C, and followed by a quench Into Ice water, ambient air, or cooled In the press with the power off. Film thicknesses ranged between 0.05-0.15 mm. Another sa(q>le of the 40/60 PET/POB copolyester was melted at 270 °C In a Mettler hot stage, manually sheared between glass slides, and then ambient air cooled. 

Numetal (386°C), Permanorm 5 (459°C), Trafoperm (754°C). The method does not permit the temperature measurement with high precision. These standards have been studied by several authors. The ICTA temperatures are within 5-10°C. McGhie et al. proposed a calibration technique in which a small inert platinum weight is suspended by a fusible link composed of a calibration standard that releases the platinum weight at the temperature of melting. The Mettler instrument TGA 850 is constructed so that the melting curve of standards can be measured and used as calibration, as demonstrated in Table 4. 

Thermal analysis involves observation of the usually very delicate response of a sample to controlled heat stimuli. The elements of thermal-analysis techniques have been known since 1887 when Le Chatelier used an elementary form of differential thermal analysis to study clays (4), but wide application did not come until the introduction of convenient instrumentation by du Pont, Perkin-Elmer, Mettler and other sources in the 1960 s. Currently, instrumentation and procedures are commercially available for DTA, DSC, TGA, TMA, and a number of so-called hyphenated methods. Several methods are currently under study by ASTM committees for consideration as to their suitability for adoption as ASTM standards. 

Because of the suspected decomposition of anhydrite, CaSO4, in lithium-based tetraborate flux systems at elevated temperatures, it was decided to study their behavior by means of thennal analysis (TGA, DTA). Thermal scans were performed on the Mettler TA-2 thermoanalyzer equipped with a DTA-20 macroholder. Platinum crucibles were filled with 200 mg of specimen flux mixtures and balanced by equal portions of alumina as the reference material. All specimens were heated at a rate of 10 C/min in an oxidation atmosphere (stream of air). 

This is one of the most frequently used methods to study solid-state properties. The flux t5q)e DSC involves heating the sample and reference samples at a constant rate using thermocouples, to determine how much heat is flowing into each sample and thus finding the differences between the two. Examples of such DSC instrumentation are those provided by Mettler and duPont. The power compensation DSC (e.g., Perkin-Elmer), an exothermic or endothermic event, occurs when a sample is heated, and the power added or subtracted to one or both of the furnaces... 

The reaction calorimeter used in this study was a Mettler s RCl with a 1 L reactor vessel. Both heat flow and hydrogen uptake were measured. The heat flow rate measured under isothermal conditions is directly proportional to a summation of the rate of each reaction step weighted by heat of reaction A// of the corresponding step, i.e.,... 

Bart et al. (62) have described the enclosure of a Mettler TA-1 thermoanalyzer in a sealed system in order to permit the examination of samples containing alpha and beta/gamma emissions. Samples containing plutonium and uranium may be studied by TG with no radiation hazard to the operator. All balance components could be reached through glove ports. 

Sample holders illustrated in (y)-(j) are used in the Mettler thermo-analvzer system. In ( ), the sample is placed in a small cup or crucible and placed on the small circular discs which contain the thermojunction. A block-type sample holder is shown in f/i) in which an alumina block is employed. The sample is contained in a crucible which may be constructed from platinum or other metals. For macro amounts of sample, the holder in (i) may be used. The containers are constructed of alumina or of different metals. If only small amounts of sample are to be studied, the micro crucible sample holder in (j) may be used. 

The first combination of thermogravimetry (TG) and a mass spectrometer was by Zitomer (36) in 1968 who coupled a Du Pont thermobalance with a time-of-flight mass spectrometer. He applied the technique to the thermal decomposition of various polymers. Lastly, Wiedemann (37) described an elaborate TG-DTA-EGD-MS system in 1969. The system consisted of a Mettler thermoanalyzer couple to a Balzer quadrupole mass spectrometer that permitted the sample to be studied at low (10 6 Torr) or normal (I atm) pressures. 

In almost every system, the Mettler Thermoanalyzer I was coupled to a quadrupole mass spectrometer, such as is illustrated in Figure 8.14 (37. 69i. The sample may be studied under vacuum 10"6 Tom or under higher pressures to 1 atm. The reaction chamber, R. is surrounded by the furnace and separated from the balance by a diffusion baffle. The evolved gases pass directly to the mass analyzer. F. which is connected to a recorder, J. through the mass spectrometer control panel. Total pressure is determined by an ionization gauge, S, which also permits the recording of the EGD curve (in this case, due to the pressure change in the system). The relation between measured total pressure and the ion current of the calibration gas permits calibration of the mass spectrometer in absolute partial pressure units or A/Torr. 

Another unusual effect associated with temperature non-uniformity in decomposing powder samples of CaCOs had been described by L vov et al. [6]. Periodic variations in the absolute decomposition rate appear during the course of decomposition (Fig. 6.4). This effect becomes more marked with an increase in the decomposition temperature and, hence, of the degree of thermal non-uniformity. The initial data for calculations of the absolute rate were obtained by Maciejewski (see [6]) for further usage in an interlaboratory study of kinetic data obtained by means of commonly accepted calculation methods [7]. These kinetic data were measured by means of a Mettler 2000C thermoanalyser during decomposition in a vacuum (5 x 10 bar) of CaCOs... 

The morphology and the isothermal radial growth rate of PEO spherulites in the blends were studied on thin films of these samples using a Reichert polarizing microscope equipped with a Mettler hot stage. The films were first melted at 85° C for 5 minutes, following which they were rapidly cooled to a fixed crystallization temperature T and the radius of the growing spherulites was measured as a function of time. 

Method Crystallization studies were carried out on an optical microscope, (Carl Zeiss), and a hot stage (Mettler FP-82). The temperature on the stage can be controlled to within O.rC and maximum cooling (or heating) rates of 20 C/min can be achieved. Glass slides and cover slips were cleaned in chromic acid and distiled water in ultrasonic bath. Polymer samples were placed between the glass slide and cover slip and pre-treated by melting to 280"C for 20 s. For crystallization studies the initial temperature, Ti, was set at 255 C. 

The process analytical technology described by Simon et al. [26] consists of a combination of an ATR UV-vis probe (Hellma Analytics) and a probe for FBRM (Mettler Toledo). The bulk phase is also monitored by BVI using a Sony video camera that captures 25 frames s . This system is well suited for studying the changes in solid particles. For monitoring the reactions driven by solid catalysts, additional Raman and ATR-FTIR spectroscopic probes can be immersed in the reaction mixture as shown in Figure 3.1. In principle, this concept is also applicable to reactions under pressure however, for such applications, stainless... 

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