Glass temperature measurement

Liquid-in-glass thermometers measure the thermal expansion of a liquid, which is placed in a solid container, on a length scale. The mercury thermometer is one example of liquid thermometers. Alcohol is also used with this type of instrument. The temperature range is -80 to a-330 °C depending on the liquid. The quality, stability, and accuracy vary considerably. The advantages are a simple construction and low price. A disadvantage is that they are not compatible for connection to monitoring systems. 

Besides readings of Earth s surface temperatures taken with standard glass thermometers, direct readings of atmospheric temperatures have been taken with satellites and weather balloons. In addition to direct measurements of Earth s recent temperatures, proxy measurements of temperatures from farther in the past can be derived from borehole temperature measurements, from historical and physical evidence regarding the e xtent and mass of land and sea ice, and from the bleaching of coral reefs. 

Apparently, annealing was not impeded by crosslinks (Fig. 5.1). The density effects observed agree with the results of the glass transition temperature measurements (Sect. 4.2). There, the Tg of the annealed (and therefore denser) sample was consistently higher by about 2 K than the Tg of the quenched polymer. 

Polymer sample temperature, measured with a thermocouple situated beneath a thin glass platform supporting the sample, depended on etch rate of the polymer the maximum temperature rise encountered in any run was 9 K, exhibited by TB after 20 min exposure to 0(3P). The... 

Probably most of these investigators were studying poly(dichlorophosphazene) in the partially crosslinked state. Most of this was summarized by Allcock (.9). More recently, highly purified, uncrosslinked II has been examined in the solid state (21). The unstressed polymer is amorphous at room temperature, but crystallization can be induced by cooling or stretching techniques. The glass transition temperature, measured by Torsional Braid Analysis, is -66°C (22). 

CombiCHEM System (Fig. 3.9) For small-scale combinatorial chemistry applications, this barrel-type rotor is available. It can hold two 24- to 96-well microtiter plates utilizing glass vials (0.5-4 mL) at up to 4 bar at 150 °C. The plates are made of Weflon (graphite-doped Teflon) to ensure uniform heating and are sealed by an inert membrane sheet. Axial rotation of the rotor tumbles the microwell plates to admix the individual samples. Temperature measurement is achieved by means of a fiber-optic probe immersed in the center of the rotor. 

The isocyanates were added to the respective resin-bound amines suspended in dichloromethane in open glass tubes. The resulting reaction mixtures were each irradiated in a single-mode microwave cavity for 2 min intervals (no temperature measurement given) (Scheme 7.52). After each step, samples were collected for on-bead FTIR analysis. Within 12 min (six irradiation cycles), each reaction had reached completion. Acid cleavage of the polymer-bound ureas furnished the corresponding hydrouracils. 

Measuring body temperature is important for the detection of disease and assessment of the response to treatments. The first thermometer was developed by Galileo in 1603. Thermometers for measuring body temperature have been in use since about 1870. The first measurements taken were axillary, and later oral and rectal measuring methods were introduced. The working principle of those thermometers, the expansion of matter by temperature increase, is still used for body temperature measurement in mercury-in-glass thermometers. Electronic thermo-... 

The infrared ear thermometer is a major step in the development of thermometers for body temperature measurements. Compared to traditional mercury-in-glass or electronic contact thermometers it is more convenient, safer and faster. During its 10 years in the consumer market it has been gradually replacing conventional thermometers, especially for temperature measuring in children. 

Figure 11.1a shows a scheme of a widely used reaction vessel for isoperibol titration calorimetry [211]. It consists of a silvered glass Dewar A, which can be adjusted to a lid B supporting a stirrer C, a resistance D for electrical calibration, a thermistor E for temperature measurement, and a Teflon tube F for titrant delivery. The assembled Dewar and lid set-up is immersed in a constant... 

The glass temperatures by DTMA measurements can be higher, depending on the frequency. 

The glass transition temperatures of polymethylpentenes by DSC measurements are generally in the room temperature range, from 20°C up to 30°C. The glass temperatures by DTMA measurements can be higher, depending on the frequency. 

D. Axelson These spectra were obtained at 57.9 MHz, but that s not the problem. We can measure correlation times regardless of the frequency. The correlation time at the glass temperature is very long. From a measurement of the correlation time we should be able to tell whether it is a true glass. In all these cases the correlation times are six to nine orders of magnitude lower than can possibly exist in a glass. For this reason I think the correlation between the NMR measurement and dielectric relaxation and dynamic mechanical do not relate one to one because of the frequency effects in the other measurements. 

D. Axelson As we have already pointed out, the correlation time is frequency-independent. The longest correlation time that we have measured is about 10" s. Whether the results correlate well with the glass temperature depends on the value one accepts for linear and branched polyethylene. Those values have been a controversial matter. 

D. Axelson Carbon-13 NMR allows for the measurement of the average correlation time for each individual carbon atom. For the glass temperature problem we are obviously only concerned with the correlation time of the backbone carbons. 

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