BEHAVIOUR OF LIGNOCELLULOSIC MATERIALS DURING WET AGING IN THE PRESENCE OF ESSENTIAL OILS

摘要

The pH of water extracts of lignocellulosic materials usually indicates a deep chemical change in their structure and composition during aging. The process of aging is connected with the hydrolysis of lignocellulosic materials during their storage under different conditions. Therefore, the dependences of mechanical, optical properties and pH of water extracts upon relative air humidity are not simple functions, but are strongly influenced by the presence of essential oils. An explanation of this behaviour is based on the condensation of water vapours in the porous structures of lignocellulosic materials depending upon both the structure of the pores and the surface-molecular properties of pore interfaces. The submicropores are especially important, because the pH of the water condensed in these pores is strongly influenced by the presence and character of acidic surface groups. Also, the presence of essential oil vapours has been found to distinctly decrease the amount of condensed water.