The effect of chemical treatments on the cellular structure of cork

Abstract

The effect of chemical treatments on the cellular structure of cork from Quercus suber L. was studied using SEM. Treatments included successive solvent extractions with petroleum ether, ethanol and water; desuberinisation with NaOCH3 in methanol; and delignification with HNOJ in CH3COOH. Solvents swell cork anisotropically, with considerably larger dimensional increases in the radial direction, but removal of extractives does not change its cellular structure. The properties of cork are affected by the chemical treatments that react with and remove the main cell wall structural components. The removal of suberin leaves holed cell walls and reveals a loose ribbonlike network; lignin acts as a supporting framework and delignified cell walls collapse. In both cases, cork looses its low density, compressibility and resilience.