Correlation of Water Vapor Adsorption Behavior of Wood with Surface Thermodyanmic Properties

摘要

To improve the overall performance of wool-plastic composites, appropriate technoligies are needed to control moisture sorption and to improve the interaction of wood fiber with selected hydrophobic matrices. The objective of this study was to determine the surface thermodynamic characteristics of a wood fiber and to correlate those characteristics with the fiber's water vapor adsorption behavior. The surface thermodynamic properties, determined by inverse gas chromatography at infinite dilution or near zero surface coverage, were the dispersive component of the surface enrgy, surface acid-base free energy and enthalpy of desorption of acid-base probes, and surface acid-base acceptor and donor parameters (K_A and K_D). Water vapor adsorption was expressed in terms of the percentage of weight gain (#DELTA# W%) resulting from water vapor adsorption on the wood particles, calclated relative to their initial weight aftre preconditioning in a vacuum dessicator at room temperature. The results showed a strong correlation between #DELTA#W% and K_A, and between #DELTA#W% and surface acid-base free energy of water desorption (#DELTA#H~AB_water), calculated from experimental K_A and K_D and values in the literature for acceptor and donor values of water. These results suggest that for substrates such as wood, whose surface Lewis acid-base properties are characterized by a relatively stronger tendency to accept electrons, the key to controlling water vapor adsorption is to manipulate the magnitude of #DELTA#H~AB_water, promarily via K_A, and to a lesser extent via K_D.