Finite element modeling of anomalous moisture diffusion with dual stage model

Fan, Xuejun; Nagaraj, Vishal

doi:10.1109/ectc.2012.6248987

Cited by 6 publications

(2 citation statements)

References 13 publications

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“…By the curves of the films with 0.6 g silica gel/g film a non-linear behavior is shown starting at m t /m ∞ values above 0.7, indicating a pseudo-Fick’s absorption behavior that occurs at accelerated diffusions. Pseudo-Fick’s absorption is described phenomenologically by other research groups with the dual-stage model [82,83,84,85]. It is based on the superposition of two sorption processes, e.g., two dual-stage sorption processes, which can be described by two diffusion coefficients and two sorption coefficients.…”

Section: Resultsmentioning

confidence: 99%

Desiccant Films Made of Low-Density Polyethylene with Dispersed Silica Gel—Water Vapor Absorption, Permeability (H2O, N2, O2, CO2), and Mechanical Properties

2019

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Silica gel is a well-known desiccant. Through dispersion of silica gel in a polymer, films can be made that absorb and desorb water vapor. The water vapor absorption becomes reversible by exposing such films to a water vapor pressure below that of the water vapor pressure during absorption, or by heating the film. The intention of this study was to achieve a better understanding about the water vapor absorption, permeability (H2O, N2, O2, CO2), and mechanical properties of films with dispersed silica gel. Low-density polyethylene (PE-LD) monolayer films with a nominal silica gel concentration of 0.2, 0.4, and 0.6 g dispersed silica gel per 1 g film (PE-LD) were prepared and they absorbed up to 0.08 g water vapor per 1 g of film. The water vapor absorption as a function of time was described by using effective diffusion coefficients. The steady state (effective) water vapor permeation coefficients of the films with dispersed silica gel were a factor of 2 to 14 (8.4 to 60.2·10−12 mg·cm·(cm²·s·Pa)−1, 23 °C) higher than for pure PE-LD films (4.3·10−12 mg·cm·(cm²·s·Pa)−1, 23 °C). On the other hand, the steady state gas permeabilities for N2, O2, and CO2 were reduced to around one-third of the pure PE-LD films. An important result is that (effective) water vapor permeation coefficients calculated from results of sorption and measured by permeation experiments yielded similar values. It has been found that it is possible to describe the sorption and diffusion behavior of water by knowing the permeability coefficient and the sorption capacity of the film (Peff.≈Seff.·Deff.). The tensile stress changed only slightly (values between 10 and 14 N mm−²), while the tensile strain at break was reduced with higher nominal silica gel concentration from 318 length-% (pure PE-LD film) to 5 length-% (PE-LD with 0.6 g dispersed silica gel per 1 g film).

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Section: Resultsmentioning

confidence: 99%

Desiccant Films Made of Low-Density Polyethylene with Dispersed Silica Gel—Water Vapor Absorption, Permeability (H2O, N2, O2, CO2), and Mechanical Properties

2019

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“…Investigation of the water absorption mechanism in polyethylene glycol diacrylate (PEGDA) films proves to follow a typical two-stage sorption process, initially governed by Fickian diffusion, followed by polymer swelling [6,8]. It is widely accepted that water in hydrophilic polymers can be present in two-states: free and bound water [9] and consequently the distinction between them is made when modelling moisture uptake in polymer matrix systems [10][11][12]. As such the adsorption and desorption reaction of water in the polymer matrix has 4 been described based on an adapted Langmuir isotherm as a function of its adsorption and desorption rate constants and their respective surface coverage [13,14].…”

Section: Introductionmentioning

confidence: 99%