Thermometer function analysis

Synthesis of Siloxane-Polyimide Elastoplastics. In a typical polymerization, a 5-L, three-neck, round-bottom flask equipped with an overhead mechanical stirrer, a Dean-Stark trap with condenser and a nitrogen inlet, and a thermometer was charged with 484.00 g (0.2406 mol) of D2o-DiSiAn, 41.61 g (0.431 mol) of mPD, 19.52 g (3 wt %) of 2-hydroxypyridine, and 2 L of o-dichlorobenzene. The mixture was warmed to 100 °C for 1 h to dissolve the monomers and the catalyst. The polyamic acids precipitated and then redissolved when the mixture was warmed to 150 °C for 2 h. To the oligomer solution was added 99.13 g of BPADA dissolved in 200 mL of o-dichlorobenzene. The mixture was maintained at 150 °C for an additional 2-h period to ensure incorporation of the dianhydride and then warmed to reflux. After approximately 100 mL of a solvent-water mixture had been removed, the solution was maintained at 180 °C for 40 h. The mixture was cooled to room temperature and diluted with 1 L of methylene chloride. Polymer was isolated from the solution by a slow addition of the polymer solution to 4 L of methanol. The resulting slurry was filtered, and the polymer was redissolved in 4 L of methylene chloride, extracted three times with 2 N aqueous HCl to remove catalyst, washed with water, dried with magnesium sulfate, reprecipitated into methanol as before, filtered, and dried in vacuo at 100 °C to obtain 522 g (85%) of a rubbery material with an IV of 0.50 dL/g. IR, NMR, and Si NMR spectroscopic analysis indicated the absence of amic acid functionalities that could be present if imidization is incomplete. 

Prior to the advent of sophisticated mechanical and electrical instrumentation, the observation of thermal phenomena was restricted to systems which were amenable to detection by the human senses. Such observations included investigations of boiling or melting processes, sublimation, fractional crystallization, color changes and the occurrence of odors. With the invention of the thermometer, the first quantitative experiment was made possible. Development of thermometry led to "thermal analysis by recording the temperature of a test material as a function of time. Further developments led to calorimetry — the science of measuring quantities of heat. 

A typical loss and heat capacity calculation is indicated at the bottom of Fig. 5.4. The curve represents the adiabatic deviation, - Tg. In the initial isothermal period, the temperature change (drift) of the sample was followed with the platinum resistance thermometer as a function of time so that the initial drift, R, could be established, as is also shown in the analysis of heat loss of Fig. 5.3. The last temperature measurement of the sample before the heat addition, is T. The heater, monitored by the watt-hour meter,... 

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