The effects of water absorption and salt fog exposure on agglomerated cork compressive response

The replacement of synthetic foams with agglomerated cork in sandwich composites can meet the increasing environmental concerns. Its peculiar morphology and chemical composition lead to outstanding dimensional recovery that endorsed a broad investigation of its compressive behavior. The knowledge of neat material response is fundamental to obtain a reliable design dataset, but it is necessary to consider all the environmental factors (water, moisture and sunlight) that significantly modify material mechanical properties. In view of this, the present work investigates the effect of distilled and seawater absorption and salt fog exposure on the compressive behavior of two agglomerated corks with different densities to simulate their potential employment in marine environment. The results were suitably compared with the ones of a traditional PVC foam used as benchmark. A dependence of water uptake and diffusivity on cork density and water type was detected. The less dense cork displayed a water uptake between 36.7 and 46.5% higher than the denser cork, and seawater uptake was between 21.8 and 44.4% lower than distilled water one. Concerning the compressive response, water and fog moisture plasticizing effect in wet conditions and a partial healing after drying due to salt crystal deposits were identified. Water plasticizing effect determined a reduction in the compressive modulus between 35.1 and 37.9% for the lighter cork and between 17.7 and 21% for the denser cork whereas fog moisture induced a reduction between 52 and 74% for the lighter cork and between 24 and 76.1% for the denser one.