Structural and Mechanical Modification Induced by Water Content in Giant Wild Reed (A. donax L.)

Giant wild reed Arundo donax L. is an aggressive agricultural species with remarkable features such as fast-growing, untapped economic potential, eco-friendliness, and high specific properties (e.g., high strength/weight and modulus/weight ratios). Here, the bending properties of giant reed were studied at a molecular level to evaluate the effect of the conditions used during the preparation for their applications (also referred to as treatment conditions). The aim was to achieve new information potentially useful to suggest new possible applications of A. donax L. for structural applications in modern buildings. In this study, green reeds collected in a Sicilian plantation were dried for 2000 h in a climatic chamber under humidity-temperature-controlled conditions, then fully dried in an oven and finally re-moistened through two different procedures. The combination of different analytical techniques (such as calorimetry and fast field cycling NMR relaxometry) revealed that giant reed bending properties are strongly affected by the presence of bound water. In particular, it has been evidenced that a progressive enhancement of bending characteristics is obtained when the interactions between residual water and A. donax L. fibers become progressively stronger. For this reason, it can be suggested that fibers having different plasticity can be produced by modulate the heating treatment to regulate the amount of bound water inside A. donax L. fibers.