Analyzers calorimeters

Thermal Properties. The glass transition temperature (Tg) and the decomposition temperature (Td) were measured with a DuPont 910 Differential Scanning Calorimeter (DSC) calibrated with indium. The standard heating rate for all polymers was 10 °C/min. Thermogravimetric analysis (TGA) was performed on a DuPont 951 Thermogravimetric Analyzer at a heating rate of 20 °C/min. 

For small amounts of powder, dissolution of the particulate material can often be assessed (and compared with that of other compounds) by placing the powder in a calorimeter [68] and measuring the heat evolved as a function of time. The surface area must be assessed microscopically (or by image analyzer), and the data must be plotted by a cube root equation [39] ... 

Chemical compatibility and U.S. EPA Method 9090 tests must be performed on the synthetics that will be used to construct FMLs. Unfortunately, there is usually a lag period between the time these tests are performed and the actual construction of a facility. It is very rare that at the time of the 9090 test, enough material is purchased to construct the liner. This means that the material used for testing is not typically from the same production lot as the synthetics installed in the field. The molecular structure of different polymers can be analyzed through differential scanning calorimeter... 

Now, it is necessary to calibrate the calorimeter in order to analyze quantitatively the recorded thermograms and determine the amount of heat evolved by the interaction of a dose of gas with the adsorbent surface. The use of a standard substance or of a standard reaction is certainly the most simple and reliable method, though indirect, for calibrating a calorimeter, since it does not require any modification of the inner cell arrangement. [For a recent review on calibration procedures, see 72).3 No standard adsorbent-adsorbate system has been defined, however, and the direct electrical calibration must therefore be used. It should be remarked, moreover, that the comparison of the experimental heat of a catalytic reaction with the known change of enthalpy associated with the reaction at the same temperature provides, in some favorable cases, a direct control of the electrical calibration (see Section VII.C). 

A DuPont 910 differential scanning calorimeter (DSC) and a DuPont 951 thermogravimetric analyzer (TGA) connected to a DuPont 1090 thermal analyzer 3ftre used to study the transition data, thermal stability, and char yield, respectively, for all the polymers. The DSC was run under a nitrogen stream at a flow rate of 80 c.c./min. and at a heating rate of 20°C/min.. 

Adiabatic calorimeters are complex home-made instruments, and the measurements are time-consuming. Less accurate but easy to use commercial differential scanning calorimeters (DSCs) [18, 19] are a frequently used alternative. The method involves measurement of the temperature of both a sample and a reference sample and the differential emphasizes the difference between the sample and the reference. The two main types of DSC are heat flux and power-compensated instruments. In a heat flux DSC, as in the older differential thermal analyzers (DTA), the... 

The experimental procedure was as described, the only difference being that a capillary containing a suitable amount of I2 was dropped into the reaction vessel (and the calorimeter allowed to stabilize) before the Cr(CO)6 sample was dropped. After recording the thermogram corresponding to reaction 9.15, the cell was removed and the contents analyzed to determine n (which varied from 0.30 to 0.38 in five separate experiments). 

W. P. Brennan, B. Miller, J. Whitwell. An Improved Method of Analyzing Curves in Differential Scanning Calorimeters. Ind. Eng. Chem. Fundam. 1969, 8, 314-318. 

Na (aq) -I- Cl (aq) - - H20(f) Assume that you have a coffee-cup calorimeter, solid NaOH, 1.00 mol/L HCl(aq), 1.00 mol/L NaOH(aq), and standard laboratory equipment. Write a step-by-step procedure for the investigation. Then outline a plan for analyzing your data. Be sure to include appropriate safety precautions. If time permits, obtain your teacher s approval and carry out the investigation. 

A differential scanning calorimeter (DSC), Dupont Instrument, Model DSC2910, was used to determine the glass transition temperatures. Thermo-gravimetric analyses were carried on a thermogravimetric analyzer (TGA), TA Instruments, Model Hi-Res TGA 2950. 

ASTM E 967-92, Standard Practice for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers, 1992. 

The glass transition (Ta) and melting (Tm) temperature of the pure component polymers and their blends were determined on a Perkin-Elmer (DSC-4) differential scanning calorimeter and Thermal Analysis Data Station (TADS). All materials were analyzed at a heating and cooling rate of 20°C min-1 under a purge of dry nitrogen. Dynamic mechanical properties were determined with a Polymer Laboratories, Inc. dynamic mechanical thermal analyzer interfaced to a Hewlett-Packard microcomputer. The... 

All enthalpy of solution measurements were carried out with an LKB 8700-1 precision calorimetry system. The experimental procedure and tests of the calorimeter have been reported previously (3, 4, 5). The purification of the solvent DMF (Baker Analyzed Reagent) and of all solutes used has been described in the same papers. The solvent mixtures were prepared by weighing and the mole fraction of water in the DMF-water mixtures was corrected for the original water content of the amide as measured by Karl Fischer titration. 

Differential thermal analysis was performed with the DuPont 900 differential thermal analyzer the heating rate was usually 10°C. per minute. To determine heats of reaction, the calorimeter attachment to the Du Pont instrument was employed. Planimeter determinations of peak areas were converted to heat values by using standard calibration curves. For the infrared spectra either a Beckman IR5A instrument or a Perkin Elmer 521 spectrophotometer with a Barnes Engineering temperature-controlled chamber, maintained dry, was used. Specimens for infrared were examined, respectively, as Nujol mulls on a NaCl prism or as finely divided powders, sandwiched between two AgCl plates. For x-ray diffraction studies, the acid-soap samples were enclosed in a fine capillary. Exposures were 1.5 hours in standard Norelco equipment with Cu Ko radiation. For powder patterns the specimen-to-film distance was 57.3 mm. and, for long-spacing determinations, 156 mm. 

In the CSM laboratory, Rueff et al. (1988) used a Perkin-Elmer differential scanning calorimeter (DSC-2), with sample containers modified for high pressure, to obtain methane hydrate heat capacity (245-259 K) and heat of dissociation (285 K), which were accurate to within 20%. Rueff (1985) was able to analyze his data to account for the portion of the sample that was ice, in an extension of work done earlier (Rueff and Sloan, 1985) to measure the thermal properties of hydrates in sediments. At Rice University, Lievois (1987) developed a twin-cell heat flux calorimeter and made AH measurements at 278.15 and 283.15 K to within 2.6%. More recently, at CSM a method was developed using the Setaram high pressure (heat-flux) micro-DSC VII (Gupta, 2007) to determine the heat capacity and heats of dissociation of methane hydrate at 277-283 K and at pressures of 5-20 MPa to within 2%. See Section 6.3.2 for gas hydrate heat capacity and heats of dissociation data. Figure 6.6 shows a schematic of the heat flux DSC system. In heat flux DSC, the heat flow necessary to achieve a zero temperature difference between the reference and sample cells is measured through the thermocouples linked to each of the cells. For more details on the principles of calorimetry the reader is referred to Hohne et al. (2003) and Brown (1998). 

Figure 18.11. Schematic of (A) a differential thermal analyzer and (B) differential scanning calorimeter for a TA Instruments, Inc.-type configuration. Modified from Richardson (1989). Reproduced by permission of Elsevier, Ltd.

Enthalpy changes can also be measured directly in a calorimeter. The temperature dependence of kinetic parameters can be interpreted in terms of AH values. In analyzing the enthalpies it is essential to recognize the chemical processes that actually contribute to the particular AH-value. 

The energy involved in the folding and association of copolymer chains in solutions can be measured by a micro-calorimeter (MicroCal Inc). We used US-DSC at an external pressure of 180 kPa. The cell volume is only 0.157 mL. The heating rate can be varied and the instrument response time is normally a few seconds. All the DSC data should be corrected for instrument response time and can be analyzed using the software in the calorimeter. Note that the concentration used in DSC is normally not lower than 10-3 g/mL, much higher than that used in LLS (10 6-10 3 g/mL). 

Figure 1. The Ferkin-Elmer laboratory for thermal analysis. From left to right the DSC-1B differential scanning calorimeter with evolved gas analyzer, the TGS-1 thermobalance (top to bottom), the recorder chart control, model UU-1 temperature programmer control, and model TMS-1 control unit. At right is the model TMS-1 thermomechanical analyzer.

In renewable energy processes, the gaseous fuels include GH2, biodegradation-generated methane, and other gases. Calorimeters are analyzers that measure the heat value or energy content of gaseous fuels. There are two... 

For adiabatic type calorimeters, the initial and the final temperatures are by definition different. To which temperature will a derived A//-value then refer In connection with microcalorimetric measurements, the problem may merely be academic as the temperature change may be very small. However, it is at this point instructive to analyze in some detail what we do when we calibrate an adiabatic calorimeter. Let the initial and the final state of the experimental process be represented by A and B and the corresponding temperatures by TA and TB, respectively. The experimental process is thus ... 

The Cone Calorimeter was equipped with a conveyor belt (Figure 16.13) to allow for continuous supply of small samples to pass under the cone heater for testing this is called RCC. Similar to a conventional Cone [35], the combustion products (smoke, CO, C02, etc.) are analyzed with the primary measurement being the amount of 02 consumed while burning. The operation procedure of the RCC and the conventional cone (ASTM 1354) are quite different as the RCC uses significantly smaller specimens and the test is continuous. In these studies, both the RCC and conventional cone were operated at a heat flux of 35 kW/m2. The absolute values for the RCC and conventional cone are not identical, since the sample masses are different, but the result... 

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