Hygroscopic behavior of cellulose acetate: A preliminary study for the production of an environmentally responsive laminate

Cellulose-based materials are well known for their significantly high hygroscopicity. Although this behavior is often considered a disadvantage affecting the performance of products made from these materials, in a few cases the deformation induced by moisture absorption of cellulose-based materials has been considered as an opportunity. In this study, we focused on the evaluation of the moisture absorption and the relevant induced expansion of cellulose acetate (about 54% of acetylation). The final goal of the research is to optimize the design of an environmentally responsive bi-layered textile, to be used in emergency shelters construction, obtained by coupling a film of cellulose acetate to a substrate made from a non-hygroscopic material. The coefficient of diffusion of the pure cellulose acetate and its relative humidity dependency has been evaluated, up to now at room temperature, by measuring the weight variation of preliminarily dried films, due to moisture adsorption in a humidity-controlled chamber. The hygroscopic expansion coefficient of the pure cellulose acetate has been determined by optical measurements. This preliminary study, which is still in progress, could provide the material properties required for finite element modeling to predict the moisture-induced curvature of the bi-layered textile.