Effects of aging in salt spray conditions on flax and flax/basalt reinforced composites: Wettability and dynamic mechanical properties

In the last years, the industrial policies are more attentive to issues concerning sustainability, recycling and environmental care. Therefore, the use of natural fibres in composite materials has spread more and more. This paper deals with flax and basalt fibres within an epoxy matrix by investigating the wettability and the dynamic mechanical properties of the resulting composites, subjected to long-term aging tests in critical environmental conditions. The first laminate was constituted by stacking ten layers of bidirectional flax fabrics. The second one was produced by replacing two external flax layers with two layers of basalt mat, for each side of the laminate. Both laminates were exposed to salt-fog environmental conditions, according to ASTM B 117 standard, for 60 days. Every 15 days of aging, the wettability and the dynamic mechanical properties of both laminates were evaluated. The results of wettability were compared with those of the water uptake test obtained in a previous work. Moreover, an analysis of variance (ANOVA) was performed in order to evaluate how some parameters (i.e. aging condition and material) and their interaction influence the mechanical and surface properties of investigated composites. Finally, a dynamic mechanical analysis was carried out in order to compare the effects of aging on the bulk properties of the investigated laminates.