Pont Thermobalance

An atmosphere control system for the thermobalance, as described by Williams (37), permits the rapid changing of the dynamic gas atmosphere between oxygen, hydrogen, and argon. 

Enclosure of the Du Pont thermobalance in a high-pressure chamber has been described by Brown et al. (37) and Williams et al. 138). Pressures of up to 20 atm and a maximum temperature of 350°C were possible with the former, while the latter instrument could be operated up to 68 atm and a maximum temperature of 450°C. The modification by Williams et al. (38) also permitted simultaneous magnetic susceptibility measurements on the 

The Derivatograph, which was first described by Paulik et al. (35) in 1958, is a multifunction thermal analysis system which can record the TG, DTG, DTA, and T curves of a sample on a single chart. By means of accessory attachments, the TD (thermal dilation) and DTD (derivative of TD) (5) curves may be recorded as well as the evolved gas curves (see Chapter 8). 

The Mettler TA1 thermoanalyzer, as developed by Wiedemann (3, 60), was perhaps the most elaborate and versatile of any thermobalance ever constructed. It is no longer available commercially, having been superseded by the Mettler TA 2000 and TA 3000 systems. However, because of its uniqueness, the Mettler TAl is described here. 

Another gas stream, which is brought through the balance mechanism, H, and the baffle, R, is used to prevent vapors from condensing on the sample-holder support rod or the balance chamber. Containers B and C are reservoirs for adding liquid to A. A water-cooled condenser at I condenses the vapor to a liquid which is then returned to boiler A. 

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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. 

Williams and Wendlandt (68) have described a high-pressure thermobalance based on the Du Pont Model 950 balance and capable of operation at temperatures of 500°C and 500 atm pressure. A schematic diagram of the balance enclosure is shown in Figure 3.34. The balance chamber was machined in the form of a cylinder from stainless steel. The furnace was insulated with Marinite which was machined to fit inside the pressure vessel and extent from the inner plato to the front of the balance housing. Provision was made for fitting the furnace within the insulated chamber and permitting... 

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