The Thermodynamic Characterization of Wetting by Submitting a Sessile Drop to Microgravity

10.20944/preprints201708.0062.v2 ◽

2017 ◽

Author(s):

Alfredo Calvimontes

Keyword(s):

High Speed ◽

Evaluation Method ◽

Sessile Drop ◽

Thermodynamic Characterization ◽

Drop Shape ◽

Interfacial Energies ◽

A New Technique ◽

System Interfaces ◽

Solid Liquid

A new technique, the sessile drop accelerometry (SDACC) for the study and measurement of the interfacial energies of solid-liquid-gas systems is tested and discussed in this study. The instrument –a combination of a goniometer with high speed camera and a laboratory drop tower- and the evaluation method, were designed to evaluate the interfacial energies as a function of the geometrical changes of a sessile drop shape due to the effect of “switching off” gravity during the experiment. The method bases on the thermodynamic equilibrium of the system interfaces and not on the balance of bi-dimensional tensors on the solid-liquid-gas contour line. A comparison of the model with the widely accepted Young`s equation is discussed in this study.

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The Measurement of the Surface Energy of Solids by Sessile Drop Accelerometry

10.20944/preprints201708.0062.v3 ◽

2017 ◽

Author(s):

Alfredo Calvimontes

Keyword(s):

High Speed ◽

Sessile Drop ◽

High Speed Camera ◽

Sessile Droplet ◽

Droplet Shape ◽

Drop Shape ◽

Interfacial Energies ◽

System Interfaces ◽

Solid Liquid ◽

The Mathematical Model

A new method, the sessile drop accelerometry (SDACC) for the study and measurement of the interfacial energies of solid-liquid-gas systems, is tested and discussed in this study. The laboratory instrument and technique –a combination of a drop shape analyzer with high-speed camera and a laboratory drop tower- and the evaluation algorithms, were designed to calculate the interfacial energies as a function of the geometrical changes of a sessile droplet shape due to the effect of “switching off” gravity during the experiment. The method bases on the thermodynamic equilibrium of the system interfaces and not on the balance of bi-dimensional tensions on the solid-liquid-gas contour line. A comparison of the mathematical model that supports the method with the widely accepted Young`s equation is discussed in this study.

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Young’s Equation vs. Sessile Drop Accelerometry: A Comparison Using the Interfacial Energies of Seven Polymer-water Systems

10.20944/preprints201802.0018.v1 ◽

2018 ◽

Author(s):

Alfredo Calvimontes

Keyword(s):

High Speed ◽

Sessile Drop ◽

Water Systems ◽

Sessile Droplet ◽

Droplet Shape ◽

Drop Shape ◽

Interfacial Energies ◽

Balance Of Forces ◽

Solid Liquid ◽

The Mathematical Model

In this study, the values of the interfacial energies of seven different polymer-water systems obtained by Sessile Drop Accelerometry (SDACC) are compared with the values obtained by the Young’s-equation-based Owens-Wendt method. The SDACC laboratory instrument –a combination of a drop shape analyzer with high-speed camera and a microgravity tower- and the evaluation algorithms, are designed to measure the interfacial energies as a function of the geometrical changes of a sessile droplet shape due to the effect of “switching off” gravity during the experiment. The method bases on Thermodynamics of Interfaces and differs from the conventional aproach of the two hundred-years-old Young’s equation in that it assumes a thermodynamic equilibrium between interfaces, rather than a balance of forces on a point of the solid-liquid-gas contour line. A comparison of the mathematical model that supports the SDACC method with the widely accepted Young`s equation is discussed in detail in this study.

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