Uncertainty Quantification of Multiple Gas Transport and Sorption in Porous Polymers

Abstract

A high-fidelity physics-based model of mixed-gas transport coupled with kinetic and equilibrium adsorption is derived, and experiments were performed in order to calibrate and exercise the model. In the literature, a continuum-scale model that couples Fickian diffusion with Henry's law absorption, and kinetic Langmuir adsorption was previously developed to describe the diffusion and sorption of moisture in porous materials. Here, we expand the model to gases, rather than moisture, derive, and implement a competitive adsorption mechanism into the model to enable mixed-gas sorption. This model facilitates a mechanistic-based understanding of the sorption and diffusion processes of mixed gases in polymeric materials. Diffusion and sorption experiments were conducted for a range of partial pressures; model validation and calibration were carried out by comparing modeled mass uptake and experimental data considering the uncertainties of conceptualized (or assumed) physical processes and system parameters. Uncertainty quantification and sensitivity analysis methods are described and exercised here to demonstrate the capability of this predictive model.

General H2O Outgassing Model Applicable to Silica-Filled Silicones

“…First, the method is useful and applicable over a wide range of temperatures. Second, it can be employed for complex and overlapped outgassing peaks (or profiles) . Third, the CIR parameter space typically captures a kinetic range consistent with those obtained from other methods such as isoconversional analysis and Kissinger peak temperature analysis.…”

“…The model was tested against the TPD data obtained from three silica-filled silicones to demonstrate the generality and predictive capability of the developed outgassing model. ,,, As discussed earlier, the overall mechanism of silica water interactions assumed to remain the same. With no change in peak numbers and kinetic parameters, the peak locations are unchanged.…”

Theoretical and Experimental Investigation on the Moisture Sorption Kinetics of a PVA/LiCl Composite Membrane in a Dynamic Humidity Environment

“…The amount of pooling adsorption in the film increases significantly, and the macroscopic manifestations are that swelling occurs and the film thickness increases. , It is noteworthy that the mechanisms of pooling adsorption in a high-humidity environment are not clear at present, and the pooling adsorption process may occur near the Langmuir adsorption sites occupied by fixed moisture molecules. , The pooling moisture molecules are also not free to move, and they do not contribute to the moisture concentration gradient between the inside and outside of the membrane. Combining the above Henry absorption, Langmuir adsorption, and pooling adsorption with the diffusion process of moisture in the film, a triple-mode sorption model based on the principle of conservation of mass and Fick’s law of diffusion was constructed: − where C (mg · g –1 ) is the total moisture uptake in the film, C H (mg · g –1 ) is the amount of Henry absorption, C L (mg · g –1 ) and C P (mg · g –1 ) are the amounts of Langmuir and pooling adsorption, respectively, D (cm 2 · min –1 ) is the effective diffusion coefficient, t (min) is the time, and x (cm) is the distance in the thickness direction of the film. The absorption process of moisture in the film is similar to the dissolution process of gas in solution.…”