Influence of water and ethanol vapours on the compressive behaviour of natural cork during ageing

Abstract

The effect of the storage condition and time on the compressive behaviour of natural cork was investigated by performing quasi-static and Progressive Repeated Loading (PRL) tests. Cork cubes were exposed to water, water-ethanol and ethanol vapours for 3- and 12-months’ storage. A significant difference for the elastic modulus was observed between samples placed in contact with water (9.6 ± 3.2 MPa) and ethanol (14.3 ± 4.2 MPa) vapours after 3 months. For cork samples in contact with ethanol a significant reduction of the elastic modulus value to 6.3 ± 0.8 MPa was noted at 12 months of storage, whereas no difference was noticeable for samples in contact with water vapour. From the PRL test performed after 3 and 12 months of storage, cork exhibited a different stored energy capability according to the storage condition. A reduction of ∼40 % occurred when placed in contact with ethanol vapour, whereas it increased of ∼15 % when stored in contact with water vapour. This led to the hypothesis that between 3 and 12 months of storage, ethanol accelerated the ageing of the material, leading to modification in the mechanical behaviour of cork, compared with water vapour.