On the response of flax fiber reinforced composites under salt-fog/dry conditions: Reversible and irreversible performances degradation

Despite their scarce resistance to humid or wet conditions, natural fiber reinforced composites (NFRCs) seem be able partially recover performances under discontinuous exposition marine environment. To investigate this peculiarity, flax composite was at first subjected salt-fog spray condition 35 °C for 15 and 30 days, respectively, then stored in ‘‘dry” (i.e., 50% R.H. 22 °C) between 0 21 days. The evolution evaluated through flexural tests, water uptake contact angle measurements. Moreover, the morphology of fractured mechanical samples examined by using 3D optical microscope scanning electron (SEM). Flax experienced phenomena both reversible irreversible degradation during phase thus evidencing a relevant recovery thanks drying. Quite interestingly, laminate showed an almost complete strength, meaning that property is more strictly related mainly aging whereas greater stiffness loss probably due ones.