基于DVS技术研究木材的动态吸附特性

Study on the water vapor sorption properties of wood based on DVS techniques

利用动态水分吸附(DVS)技术测量黑桦和油松2种木材在动态吸附过程中的含水率,再通过平行指数动力学(PEK)模型分析其动态吸附特性。结果表明,相对湿度越高,木材吸附时间越长,平衡含水率越高;黑桦和油松的吸附等温线呈"S"形,是Ⅱ型吸附等温线;各个湿度阶段DVS测试与PEK模型拟合得到的平衡含水率差值小,在–0.08%～0.02%间,拟合度R2均高于0.99;PEK模型中快速(MC1)与慢速(MC2)吸附过程含水率之和近似等于该湿度阶段试样增长的含水率(ΔMC);快速吸附过程与单层吸附相似,MC1折线总体呈下降的趋势,慢速吸附过程与多层吸附相似,MC2折线总体呈上升的趋势;黑桦试样慢速特征时间(t2)范围为51.50～103.20 min,快速特征时间(t1)为3.83～9.27 min,油松试样t2范围为12.72～28.63 min,t1为3.64～7.83 min。

Dynamic vapour sorption （DVS） technique was used to measure the moisture content （MC） of Pinus tabuliformis Carriere and Betula dahurica. The dynamic sorption properties were analyzed by parallel exponential kinetics （PEK） model. It was concluded that the higher relative humidity, the longer the sorption time, and the higher equilibrium moisture content; the sorption isotherms of Pinus tabuliformis Carrikre and Betula dahurica were type II sorption isotherms with a ＂S＂ shape. The difference of equilibrium moisture content （EMC） obtained from the testing and fitting was small, in the range of-0.08%-0.02%, R2 was always higher than 0.99. The sum of the moisture content of the fast （MC1） and slow （MC2） kinetic processes in the PEK model was approximately equal to the increased moisture content （AMC） of the humidity stage. The fast kinetic process was similar to the monolayer sorption. The MC1 line showed a decreasing trend overall. The slow kinetic process was similar to multilayer sorption, and the MC2 line generally showed an upward trend, t2 and tl of Betula dahurica were in the range of 51.50-103.20 min and t1 was 3.83-9.27 min correspondingly, t2 and t1 of Pinus tabuli-formis Carriere were in the range of 12.72-28.63 min and 3.64-7.83 min respectively.