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Journal article(2023)
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Panos Apostolidis, Michael Elwardany, Adrian Andriescu, David J. Mensching, Jack Youtcheff
Glass transition parameters can be used to study the miscibility, or lack of it, in polymer-modified asphalt binders. In this study, the contribution of thermodynamics of mixing to glass transition was quantitatively assessed in a differential scanning calorimeter for four asphalt binders partially and fully replaced by an epoxy system. The values of heat capacity (Cp) and, subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given to examining the enthalpy of mixing as a function of epoxy system composition during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of the measured Tg of epoxy-modified asphalt binders (Tg,mix) obtained from the ideal mixing rule led to negative values of the entropy of mixing (ΞSmixc), dictating the presence of internal repulsive forces between the asphalt and epoxy components. Softer binders were associated with binders of low deviations of Tg,mix values from the ideal mixing rule. Lastly, the partial replacement of asphalt binders by the epoxy system increased the Tg and decreased the amount of ΞSmixc, and such performance imposes the formation of immiscible products.
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Glass transition parameters can be used to study the miscibility, or lack of it, in polymer-modified asphalt binders. In this study, the contribution of thermodynamics of mixing to glass transition was quantitatively assessed in a differential scanning calorimeter for four asphalt binders partially and fully replaced by an epoxy system. The values of heat capacity (Cp) and, subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given to examining the enthalpy of mixing as a function of epoxy system composition during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of the measured Tg of epoxy-modified asphalt binders (Tg,mix) obtained from the ideal mixing rule led to negative values of the entropy of mixing (ΞSmixc), dictating the presence of internal repulsive forces between the asphalt and epoxy components. Softer binders were associated with binders of low deviations of Tg,mix values from the ideal mixing rule. Lastly, the partial replacement of asphalt binders by the epoxy system increased the Tg and decreased the amount of ΞSmixc, and such performance imposes the formation of immiscible products.
Other(2022)
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P. Apostolidis, Adrian Andriescu, Michael Elwardany, David Mensching, Jack Youtcheff
The glass transition parameters are used to study the miscibility, or lack of it, in polymer modified asphalt binders. In this study, a quantitative assessment of the contribution of thermodynamics of mixing to glass transition was conducted in a differential scanning calorimetry for four asphalt binders modified with an elastomeric epoxy system. Especially, the values of heat capacity (Cp) and subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given on examining the enthalpy of mixing as a function of the composition of epoxy asphalt binders during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of Tg,mix obtained from the ideal mixing rule, or π₯ππ,πππ₯, led to negative values of the entropy of mixing (π₯ππππ₯π), dictating the presence of internal repulsive forces between the asphalt and epoxy components. The soft in properties and sol type base binders are also associated with epoxy asphalt binders of low π₯ππ,πππ₯ values. Overall, the incorporation of the epoxy system in asphalt binders increases the Tg and decreases the amount of π₯ππππ₯π, and such performance imposes the formation of phase-separated binders.
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The glass transition parameters are used to study the miscibility, or lack of it, in polymer modified asphalt binders. In this study, a quantitative assessment of the contribution of thermodynamics of mixing to glass transition was conducted in a differential scanning calorimetry for four asphalt binders modified with an elastomeric epoxy system. Especially, the values of heat capacity (Cp) and subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given on examining the enthalpy of mixing as a function of the composition of epoxy asphalt binders during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of Tg,mix obtained from the ideal mixing rule, or π₯ππ,πππ₯, led to negative values of the entropy of mixing (π₯ππππ₯π), dictating the presence of internal repulsive forces between the asphalt and epoxy components. The soft in properties and sol type base binders are also associated with epoxy asphalt binders of low π₯ππ,πππ₯ values. Overall, the incorporation of the epoxy system in asphalt binders increases the Tg and decreases the amount of π₯ππππ₯π, and such performance imposes the formation of phase-separated binders.
