Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Molecular Dynamic Simulation of Oxidative Aging in Asphaltene
Molecular dynamic simulation is employed to determine the thermodynamic properties of asphaltene before and after oxidative aging. The asphaltene structure used in MD simulation is a moderate size aromatic core with larger branches. For oxidative aging, the amount of oxygen considered are – 0.1%, 1%, 12%, 23% and 46.5% of total number of asphaltene atoms. Thermodynamic properties calculated from atomistic molecular simulations of asphaltene include density, glass-transition temperature and potential energy. It is shown that density increases with the increase in oxidation level up to 2.5%, and then it decreases. Density has an inverse relationship with temperature. At high temperature, density decreases as temperature increases because at high thermal energy the molecules are largely unassociated and mobilized. Glass transition temperature (Tg) is calculated from the characteristics of density vs. temperature plots. Unaged asphaltene shows a glass transition temperature of 273 K (0 °C). Tg of asphaltene decreases at highly oxidized state (> 20%). Variation of Tg as a function of oxidation can be useful in the study of hardness, brittleness, stiffness, viscosity of asphaltene. The kinetics of asphaltene aging is shown to be affected by oxidation rate and temperature. At low oxidation level, density-aging time relationship is hyperbolic and at the high oxidation level, it is nearly linear.
Molecular Dynamic Simulation of Oxidative Aging in Asphaltene
Molecular dynamic simulation is employed to determine the thermodynamic properties of asphaltene before and after oxidative aging. The asphaltene structure used in MD simulation is a moderate size aromatic core with larger branches. For oxidative aging, the amount of oxygen considered are – 0.1%, 1%, 12%, 23% and 46.5% of total number of asphaltene atoms. Thermodynamic properties calculated from atomistic molecular simulations of asphaltene include density, glass-transition temperature and potential energy. It is shown that density increases with the increase in oxidation level up to 2.5%, and then it decreases. Density has an inverse relationship with temperature. At high temperature, density decreases as temperature increases because at high thermal energy the molecules are largely unassociated and mobilized. Glass transition temperature (Tg) is calculated from the characteristics of density vs. temperature plots. Unaged asphaltene shows a glass transition temperature of 273 K (0 °C). Tg of asphaltene decreases at highly oxidized state (> 20%). Variation of Tg as a function of oxidation can be useful in the study of hardness, brittleness, stiffness, viscosity of asphaltene. The kinetics of asphaltene aging is shown to be affected by oxidation rate and temperature. At low oxidation level, density-aging time relationship is hyperbolic and at the high oxidation level, it is nearly linear.
Molecular Dynamic Simulation of Oxidative Aging in Asphaltene
Tarefder, Rafiqul A. (Autor:in) / Arisa, Iffat R. (Autor:in)
Pavements and Materials: Characterization and Modeling Symposium at EMI Conference 2010 ; 2010 ; Los Angeles, California, United States
Pavements and Materials ; 16-30
05.08.2010
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
Molecular Dynamic Simulation of Oxidative Aging in Asphaltene
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