Moisture Absorption in Highly Porous Closed‐Cell Polymeric Foams

ABSTRACT

Polymeric foams, particularly closed‐cell foams, are highly susceptible to moisture absorption, which alters critical properties such as density and ultimately diminishes their functional performance. Accurate prediction of moisture diffusion is therefore essential for estimating their long‐term durability. This study investigates the capabilities and limitations of existing absorption models in capturing moisture absorption behavior in polymeric foams. The conventional one‐dimensional hindered diffusion model (1D‐HDM) is extended to a new void‐filling hindered diffusion model (VF‐HDM) which accounts for closed‐cell porosity. The effect of foam thickness on the moisture absorption is explained by incorporating the closed‐cell porosity to the model. To validate the VF‐HDM, moisture absorption experiments were performed on closed‐cell ROHACELL WF‐71 foam. The model successfully captured distinct absorption behaviors associated with varying foam thickness by quantifying stored moisture within closed‐cells. Experimental results showed that thickness and porosity differences can lead to as much as a 62% variation in maximum absorbed moisture.