汽蒸处理对落叶松木材化学性质的影响

本文研究了兴安落叶松(Larix gmelinii Rupr.)生材于常压下,汽蒸1、2、4、8、16、32、49、64、96h,试样化学成分的变化。结果表明:汽蒸是落叶松成材干燥工艺中十分有效的预处理工序,不仅能除去影响落叶松木材气体渗透性的树脂类物质,同时还能除去影响落叶松木材液体渗透性的水溶性物质,这种水溶性物质的主要成分是阿拉伯半乳聚糖。汽蒸过程中木材的酸度逐渐增加,同时材面颜色亦随之变深。汽蒸过程中综纤维素含量稍有下降,木素含量略有增大。试样中LCC价键断裂程度加深,少量降解程度大的低聚合度级份的半纤维素由材面溶出,其它级份的半纤维素亦有不同程度的水解降解。为了彻底除去树脂中的挥发性成分,汽蒸处理时间不应少于4h。

INFLUENCE OF STEAMING ON THE CHEMICAL PROPERTIES OF LARIX WOOD

The green wood of larix gmelinii steamed at atmospheric pressure from 1 to 96 hours was analyzed. The results of the experiments are given as follows: (1)Steaming is a necessary pretreatment process of lumber drying of larix gmelinii. During steaming the resin contained of wood were removed and the water soluble matters removed too, but the amount of the former removed limited and the amount of the latter increased with steaming period. (2) The PH of the wood was reduced from 4.85 to 3.9, the color of the wood became darker. (3) The water soluble matters removed from the wood of larix gmelinii are mainly rabinogalactan during steaming. (4) The holocellulose content showed a slight decrease, and the lignin increease. (5) The hemicellulose were changed larger. The hemicellulose fraction removable by 0.2% NaoH ranged from7.2% to 9.1%, with the steaming processing, a small amount of hemicelluose, which were degradated violently, removed from the surface of sample with the steaming condensational solution. (6) From the volatile component of resin removed completely, In general, we consider that the green larch wood should not be exposed to steaming for periods shorter than 4 hours.