The Construction of a Microcalorimeter and Measurement of Heats of Solution of Stretched Glassy Polystyrene
A conduction-type twin microcalorimeter was constructed in order to measure very small amounts of heat, and the microcalorimeter was applied to measure the heat of solution (ΔH) of stretched polystyrene (glassy state). The area of the thermogram was proportional to the supplied electric energy into the micro-calorimeter in a range of 0 to 0.3 calory. As the calibration, ΔH for KCl was measured at 30°C in molar fraction, 1: 5, 500. The standard deviation was ± 0.4%. The ΔH of stretched glassy polystyrene was measured in toluene at 30°C. The specific volume of the samples was measure by floating method of each stretched sample and unstretched sample. The measured value of the specific volume did not depend on the stretched temperature and the draw ratio. However, the value of measured ΔH of stretched (at 110°C) samples decreased with the increase of the draw ratio: it decreased about 50 cal/mole at the draw ratio 3 as compared with that of unstretched sample.
KeywordsInternal Energy Draw Ratio Glassy State Rubber Elasticity Enthalpy Difference
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