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Heat Capacities of cis-1,4-Polyisoprene from 2 to 360 K
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Abstract:
Heat capacities of amorphous synthetic cis-1,4-polyisoprene have been determined for the quenched and annealed glasses from 2 to T (around 200 K) and for the liquid from T to 360 K, with a precision of better than 0.05 percent above 15 K. T as determined from H versus T plots, is 203 K for the quenched glass and 198 K for the annealed glass. For the glasses the heat capacity values from this research are about 1 percent higher than that reported in 1935 for natural rubber hydrocarbon. For the liquid the result from this research agrees better (within 1 percent) with recently (1967) proposed values than those from the earlier experiment cited. Effects of crystallization and melting, stark rubber crystals, and additives (antioxidants and stabilizers) were also studied.
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