Preparation of Chinese fir wood/MMT nanocomposites and the factors affecting it

Abstract

The nano intercalation compounding of wood and MMT has important implications for the modification of wood and for the development of new materials. With water-soluble phenol formaldehyde resin as an intermediary, the nanocomposites of Chinese fir (Cunninghamia lanceolata) wood and montmorillonite (MMT) were prepared via three impregnation methods, i.e. normal pressure, once and twice vacuum methods. Based on the weight percent gain (WPG) of impregnated wood, the effects of compounding wood and MMT in terms of concentration, impregnating temperature and time, wood moisture content and wood extraction treatments, on sapwood and heartwood are discussed. Results show that: 1) the optimum MMT concentration in the impregnation solution is 3% for sapwood and 5% for heartwood; 2) room temperature is suitable in practice; 3) treatment pressure should be set at a high enough value in order to ensure sufficient permeation; 4) the effects of different impregnation methods on sapwood and heartwood are different, the heartwood extractives affect WPG significantly; cell wall permeability of sapwood is better than that of heartwood; 5) the cold water, hot water and benzene-ethanol solution extractions can all greatly improve the permeability of heartwood, hot water can dissolve some hemicellulose of low aggregation and hot water extraction improves wood cell wall permeability; 6) with an increase in wood moisture content, the permeable space in wood is reduced, but with a certain amount of water, instantaneous spaces are created and the permeation dynamic increases. This effect is especially apparent for difficult impregnating situations in heartwood and impregnation under normal pressure.