Abstract
From new results for the equation of state of dibutylphthalate in combination with previously reported dielectric relaxation data, an analysis of the volume contribution to the dynamics was carried out for this fragile glass-former (m P =84). We find that the ratio of the isochoric and isobaric fragilities equals 0.75, the largest found to date for any molecular van der Waals liquids, reflecting a strong temperature effect, consistent with the large fragility. The relaxation times superpose when plotted versus temperature times the specific volume raised to the 3.2 power. This is a somewhat larger value of the exponent than expected based on the fragility of DBP. The implication is that for molecular glass-formers, the classical Lennard-Jones repulsive potential may represent the limit for fragile liquids.
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Casalini, R., Roland, C.M. (2007). Isobaric and isochoric properties of glass-formers. In: Rzoska, S.J., Mazur, V.A. (eds) Soft Matter under Exogenic Impacts. NATO Science Series II: Mathematics, Physics and Chemistry, vol 242. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-5872-1_9
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DOI: https://doi.org/10.1007/978-1-4020-5872-1_9
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