Glass Transition Phenomena and Rheological Properties of Petroleum Asphalt

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Abstract
Volume dilatometry was made for nine kinds of asphalt in a wide range of asphaltene content X . The glass transition temperature T g becomes higher with increase of X . The discontinuity in thermal expansion coefficient at T g decreases with X and T g can no more be observed for X >70%. The complex shear modulus and shear creep compliance of five samples of asphalt were measured. Above T g , asphalt is viscoelastic. The temperature-time reducibility applies very well to asphalt. The temperature dependence of retardation times as well as steady flow viscosity obeys to Williams-Landel-Ferry's equation, the standard temperature involved in this equation being 56° higher than T g for all the samples. The distribution function of retardation times is approximately of a wedge shape when plotted in logarithmic scales, the slope being 0.5 or less according to X . The steady flow viscosity and the maximum retardation time reduced to 20°C markedly increase with X . These facts allow us some predictions about molecular behaviors in asphalt.