Calorimetric study of thiophene-benzene solutions(I) |
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Authors: | N. Okamoto M. Oguni H. Suga |
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Affiliation: | aDepartment of Chemistry and Chemical Thermodynamics Laboratory, Faculty of Science, Osaka University, Toyonaka, Osaka 560, Japan |
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Abstract: | Molar heat capacities were measured on seven mixtures [(1 − x)thiophene + x benzene] using an adiabatic calorimeter in the 14 and 300 K temperature range. The measurements were made at x = 0.0016, 0.0030, 0.0050, 0.0061, 0.0070, 0.0183 and 0.0210, respectively. Transitions between various phases in stable and metastable sequences of thiophene crystal were found to be affected more or less by the benzene doping in this thiophene-rich region. Among others, the II2-II1 transition in the metastablephase sequence was affected drastically by the dopant. The significant effect of benzene on the transitional behavior was discussed in relation to the incommensurate structure of phase II,. Glass transitions observed in phase II1 or II2 were analyzed in terms of the Kohlrausch-Williams-Watts equation to derive kinetic parameters characterizing the relaxation processes. Non-exponential behavior of enthalpy relaxation was discussed in the light of possible distribution of relaxation times in the solid solution. |
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Keywords: | Disorder phase transition glass transition heat capacity phase diagram of thiophene-benzene solid solution |
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