Abstract:

Chinese Fir(Cunninghamia lanceolata) plantation sapwood and heartwood boards were treated by radio_frequency vacuum drying(RFVD),conventional kiln drying(KD) and high temperature drying(HT) methods. The maximum amount of dyeing solution uptake by the capillary rise method was used to evaluate the liquid impregnation properties of treated wood. The pit aspiration ratio was determined by semithin section method. Changes in the wood microstructure were investigated using scanning electron microscopy. The results showed that the liquid impregnation of Chinese Fir sapwood after radio-frequency vacuum drying is significant higher than that after conventional kiln drying and high temperature drying,there is no significant difference of liquid impregnation for Chinese Fir sapwood after conventional kiln drying and high temperature drying. The effect of radio-frequency vacuum drying and high temperature drying methods on liquid impregnation of Chinese Fir heartwood is significant,but there is no significant difference of liquid impregnation for Chinese Fir heartwood after radio-frequency vacuum drying and conventional kiln drying,high temperature drying and conventional kiln drying. The liquid impregnation of Chinese Fir sapwood is significantly higher than heartwood after three drying treatments. Low pit aspiration ratio and cracks of some bordered pits are the main reasons for increasing liquid impregnation after radio-frequency vacuum drying treatment.

Key words: Cunninghamia lanceolata, radio-frequency vacuum drying(RFVD), conventional kiln drying(KD), high temperature drying(HT), liquid impregnation, pit aspiration ratio