Thermal testing temperature range

A key factor in the suitabihty of cokes for graphite production is their isotropy as determined by the coefficient of thermal expansion. After the calcined coke was manufactured into graphite, the axial CTE values of the graphite test bars were determined using a capacitance bridge method over a temperature range of 25 to 100°C. The results are summarized in Table 24. Also included in the table are bulk density measurement of calcined cokes and the resistivity values of their graphites. 

Young s moduli were determined in tensile tests using samples of 4 mm thickness. Slow cyclic loading (frequency 0.01 Hz) with small strain amplitudes (s < 3%) was used for the tests in order to maintain the thermal equilibrium as much as possible. The temperature range was limited to 260 °C as thermal decomposition became noticeable above this temperature [11],... 

Catalytic activity for the selective oxidation of H2S was tested by a continuous flow reaction in a fixed-bed quartz tube reactor with 0.5 inch inside diameter. Gaseous H2S, O2, H2, CO, CO2 and N2 were used without further purification. Water vapor (H2O) was introduced by passing N2 through a saturator. Reaction test was conducted at a pressure of 101 kPa and in the temperature range of 150 to 300 °C on a 0.6 gram catalyst sample. Gas flow rates were controlled by a mass flow controller (Brooks, 5850 TR) and the gas compositions were analyzed by an on-line gas chromotograph equipped with a chromosil 310 coliunn and a thermal conductivity detector. 

Tests of a graphite-reinforced polyimide composite (C6000/PMR15) did not show any effect of radiation exposure (1 MEV electrons 6x109 rad total dose) on the thermal expansion behavior (14). DMA curves for unirradiated and irradiated composites were essentially identical over the temperature range of the thermal expansion measurements. 

The working principle of the thermocouple was discovered (1823) by Seebeck who observed that if wires of two different metals were joined to form a continuous circuit, a current flowed in the circuit when the two junctions were at different temperatures. In order to make a measurement, one junction (the reference junction) is maintained at a constant temperature (typically at 0°C) and the electromotive force produced when the other junction is at the test temperature is measured, or recorded, by a suitable instrument (or used as the input of a controller ). In order to choose the right kind of thermocouple among the many types available, the temperature range to be studied must be considered, as well as several requirements regarding sensitivity, calibration stability, chemical, thermal, mechanical inertia, etc. 

Persistent photosensitivity developed in eight men after occupational exposure to hot epoxy resin fiimes. The condition was limited to sites contacted by the resin. Small doses of ultraviolet-A light evoked abnormal reactions consisting of erythema, edema, and papules in the clinically involved skin. Positive photopatch tests were observed to epoxy resin in four subjects and to bisphenol A in all subjects. Another study showed that bisphenol A can be released during the thermal decomposition of epoxy resin in the temperature range of 250-350°C. Photosensitizing activity was explained by the formation of ftee radicals during exposure to ultraviolet-B radiation of bisphenol A vapor, to form a semiquinone derivative of bisphenol A ... 

These studies fall into two groups,"dynamic" and"static heat treatments,In the dynamic heat treatment,samples are heated using a broad temperature range/20 to 300°C/ for a short time,Such tests include the Thermal Evolution Analysis/TEA/ and pyrolysis thin-layer chromatography /TAS/ /3,4/,... 

The variation of the damping factor (tan 5) with temperature was measured using a Polymer Laboratories Dynamic Mechanical Thermal Analyzer (DMTA). The measurements were performed on the siloxanfe-modified epoxies over a temperature range of — 150° to 200 °C at a heating rate of 5 °C per minute and a frequency of 1 Hz. The sample dimensions were the same as those used for flexural modulus test specimens. 

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