Thermometer, Beckman

The.Crvstallia Cell Where All The Experiments were Perfarmed. This was a 1 liter pyiex vessel covered by a 1 cm thick plexiglass cover. Holes in the plexiglass cover permitted the introduction of a Beckman thermometer and a specially constructed stirrer capable of accommodating two ice seed crystals on its blades. These seed crystals were attached to the tips of the stirrer blades by a slow freezing process of water in contact with the tips of the stirrer. 

A Beckman thermometer is used to read the temperature of the bath. When the temperature of the Wood s metal bath is -300 °C, a test tube with a sample is immersed in it. A stopwatch is used to record the time interval between the moment of immersion of sample in the bath and the moment of its explosion. If the explosion delay (ED) is more than 10/5 seconds, the temperature of the bath is increased by 10 °C and the experiment is repeated with a fresh sample. This exercise is repeated with incremental temperature changes (higher or lower) until an exact ED of 10-/5- seconds is obtained. This method is similar to that described by Weber in the literature [24]. 

Ebullioraetry, like end-group analysis, is limited to low-raolecular-weight polymers. By use of thermistors sensitive to O.OOOFC, it is possible to measure molecular weight values up to 50,000, although typical limits (using Beckman thermometer with temperature difference measurement accuracy of 0.001°C) are 5,000. 

Thermometric titrations can be implemented with a buret, a Dewar flask, and a Beckman thermometer, as in early studies. In modern instrumentation, however. 

The test is performed with 0.2 g of a sample that is previously dried and ground to a suitable particle size. The sample, placed in a test tube, is immersed in a liquid metal bath (usually Wood s alloy) vdien the temperature in the bath reaches 100 °C. Three samples are tested simultaneously. An electric motor connected with a Beckman thermometer provides the heating rate of either 5 °C/min or 20 °C/min. When the ignition of the sample occurs, accompanied by a crack or whistle, the temperature is read out from the control thermometer. 

A Beckman thermometer is used to ensure a desired temperature. When the temperature stabilises, a test tube with the sample is immersed in a liquid alloy bath. A stop-watch is used to register the time interval between the immersion of the sample in the alloy and the ignition. This time period is the induction period. 

The sample may be freely poured into the sample vessel or pressed in the form of a pastille using a special hand-operated press. The wire for the electric ignition is inserted through the middle of the sample. To ensure successful ignition, the middle part of the wire is coiled. Finally, the bomb is closed with the screw cap, and the air is evacuated by the vacuum pump until a vacuum of only a few millibars is attained. The calorimetric bomb is now placed into the inner calorimetric vessel. The electric conductors for the sample ignition are connected with the connectors on the cap of the bomb. A previously measured volume of water at operating temperature is poured into the inner calorimetric vessel. The cover of the calorimetric vessel is then closed, followed by the ignition via the electric switch. The temperature increase in the inner calorimetric vessel is followed by the Beckman thermometer. 

All absorbance data were obtained on a Beckman DU-2 spectrophotometer, and quartz cells of 1 cm path length were used. The apparatus used was essentially a three-necked round-bottomed flask fitted with an electric stirrer and a thermometer the third neck was left unoccupied for addition of... 

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