Dynamic Triple-Mode Sorption and Outgassing in Materials

Abstract

Moisture uptake and outgassing can be detrimental to a system by altering the chemical and mechanical properties of materials within the system over time. In this work, we conducted isotherm experiments to investigate dynamic moisture sorption and desorption in markedly different materials, i.e., a polymeric material, Sylgard-184 and a ceramic aluminosilicate material, Zircar RS-1200, at different temperatures (30 °C–70 °C) by varying the water activity (0.0–0.90). Sylgard-184 showed a linear sorption and outgassing behavior with no-hysteresis over the entire temperature and water activity range considered here. Whereas, the sorption and outgassing of Zircar RS-1200 was highly non-linear with significant hysteresis, especially at higher water activities, at all temperatures considered here. The type of hysteresis suggested the presence of mesopores in Zircar RS-1200, whereas the lack of hysteresis in Sylgard-184 indicates that it has a nonporous structure. A diffusion model coupled with a dynamic, triple-mode sorption (Langmuir, Henry, and pooling modes) model employed in this study matched our experimental data very well and provides mechanistic insight into the processes. Our triple-mode sorption model was adaptive enough to (1) model these distinctly different materials and (2) predict sorption and outgassing under conditions that are distinctly different from the parameterization experiments.

Uncertainty Quantification of Multiple Gas Transport and Sorption in Porous Polymers

“…(17). This approach has been used successfully in the past to calibrate reactive transport systems in high-dimensional parameter space (e.g., Sharma et al 2017Sharma et al , 2018.…”

“…For this reason, Langmuir adsorption and pooling/clustering are often treated as equilibrium reactions, and both the adsorbed and clustered concentrations can be calculated as secondary state variables that are not directly solved in partial differential equations for transport and ordinary differential equations for reaction kinetics. The dynamic nature of mass uptake in polymeric materials stimulated the study and development of kinetic adsorption models (Harley et al 2014;Sun et al 2015;Sharma et al 2017Sharma et al , 2018.…”

“…Recently, dual-and triple-mode sorption processes (Henry's absorption, kinetic Langmuir adsorption, and pooling) have been coupled with diffusion (Harley et al 2014;Sun et al 2015;Sharma et al 2017). The dynamic nature of vapor mass uptake has been presented by adsorption reaction rate, diffusivity, and material-specific tortuosity (Sharma et al 2017). However, the transport model coupled with kinetic Langmuir adsorption was limited to singlegas component (vapor) and does not catch the competitive sorption kinetics of multiple gases in polymeric materials.…”

Role of filler and its heterostructure on moisture sorption mechanisms in polyimide films

“…A polymeric material’s moisture sorption properties can be significantly altered by the addition of fillers, such as zeolites, silica, phosphate, or alumina compounds 16 – 18 . In many instances, fillers are intentionally added to alter these sorption properties.…”

Langmuir‐diffusion model: Its modification and further application to glutinous rice flour particles

“…The aforementioned models assume that all water molecules diffuse freely or equally. Reaction-diffusion model, which divides water into two or more groups with individual diffusivity, is an alternative approach for accounting for the water-matrix interactions (Sharma, Harley, Sun, & Glascoe, 2017).…”