不同干燥方法对杉木吸湿及尺寸稳定性的影响

为明确不同干燥方法对人工林杉木吸湿及尺寸稳定性的影响，以40 mm杉木锯材为研究对象，通过高温干燥、常规干燥和气干3种方法进行干燥处理，采用双室温、湿度控制法和GAB等温吸附模型拟合系统研究了干燥方法对平衡含水率、尺寸稳定性、等温吸附线型等的影响规律，并采用低温核磁共振分析测定不同干燥方法试样的细胞壁最大吸着水含量。结果表明：相较于气干及常规干燥，高温干燥可较为显著的降低试样吸湿平衡含水率及弦向线性湿胀率；不同干燥方法试样的等温吸附曲线均可由GAB模型拟合，拟合度均高于0.91，且呈现第二类等温吸附曲线特征；高温干燥试样细胞壁吸着水最大含量明显低于气干和常规干燥材，与高温干燥对平衡含水率影响规律相似。

Effects of high temperature drying on the hygroscopicity and dimensional stability of Chinese Fir

In order to clarify the effects of different drying methods on the moisture adsorption and dimensional stability of planted Chinese fir, drying of 40mm thickness Chinese fir timber was taken as the research object, three kinds of drying methods including air drying, conventional drying and high temperature drying were carried out. After different drying methods, the sorption experiments of different drying methods samples were performed in the two-chamber setup and the sorption isotherms curves were fitted by Guggenheim-Anderson-deBoer(GAB) equation. The effects of different drying methods on equilibrium moisture content, dimensional stability, and the isothermal adsorption curve were analyzed. Then, the maximum moisture content in cell wall was determined by low temperature nuclear magnetic resonance. The results showed that compared with air drying and conventional drying, the equilibrium moisture content and the linear swelling rate of sample in tangential direction can be significantly reduced after high temperature drying. The isothermal adsorption curves of samples with different drying methods can be fitted by GAB model, the fitting degree was higher than 0.91. The fitting curves all showed the characteristics of the second type of isothermal adsorption curves. The results of low temperature nuclear magnetic resonance showed that the maximum moisture content of cell wall after high temperature drying was also lower than that of air drying and conventional drying samples, which was similar to the effect of high temperature drying on equilibrium moisture content.