The effect of moisture-induced swelling on the absorption capacity of transversely isotropic elastic polymer–matrix composites

Abstract

a b s t r a c tThe interaction between humid air and transversely isotropic fiber-reinforced composites with swelling polymeric matrix is considered. A model is proposed for the water saturation level in a polymer when stresses are applied, that uses directly obtainable material parameters only. In a composite, the reinforcements modify the water uptake of the polymer matrix because of the internal stresses that are induced by its restricted swelling, and this effect is evaluated. As a consequence of the coupling between stresses and absorption capacity, the sorption isotherm of a composite is ruled by the (non-linear) Langmuir equation when the unreinforced matrix obeys the (linear) Henry's law.

Accounting for differential swelling in the multi‐physics modelling of the diffusive behaviour of polymers

“…This work is focused on developing an enhanced version of the model describing the diffusion of moisture in polymers based on the so-called thermodynamical approach first introduced by Derrien and Gilormini [6], and then improved by Sar et al [18]. For the first time, in contrast to both those references, the present paper handles the differential swelling experienced by the polymer during the moisture diffusion process.…”

“…Where F 0 is the free energy of the dry stress-free polymer, f w (C) is the variation of the free energy per mole of dry polymer, due to the addition of water when the polymer is free to swell, n and V ε are respectively the amount of polymer and its volume at any stage, whereas W denotes the hygro-elastic strain energy [6]μ…”

“…In recent works [6,18], other models, focused on the description of anomalous diffusion, were also developed which were compatible with the thermodynamics. Nevertheless, the mathematical formalism presented in both references [6,18] does not enable the effects on the moisture kinetics induced by the presence of an in-depth heterogeneous profile of the hygroelastic strain to be accounted for.…”

“…Nevertheless, the mathematical formalism presented in both references [6,18] does not enable the effects on the moisture kinetics induced by the presence of an in-depth heterogeneous profile of the hygroelastic strain to be accounted for. The present work will present a possible way to address this issue.…”

Water–Mechanical Property Coupling

“…Among the proposed methods, [11] documented a multi-physics approach to the diffusion mechanisms compatible with the thermodynamics. Recently [3,12] published a model focused on the description of anomalous diffusion also developed upon the concept of being compatible with the thermodynamics. …”