氮气吸附法表征杨木应拉木的孔隙结构

Pore Structure Characterization of Poplar Tension Wood by Nitrogen Adsorption-Desorption Method

在常规解剖特征分析的基础上,采用氮气吸附法对杨木应拉木的比表面积及孔径分布等孔结构参数进行研究,并通过解析氮气吸附等温线判断孔隙的形状。结果表明:杨木应拉木BET比表面积为21.9m2.g-1,是对应木的13倍;杨木应拉木试样具有完好的介孔特征(孔径2～50nm),并具有一定量的微孔和大孔;内部存在"墨水瓶"状和狭缝状孔隙,孔径为5nm的孔体积分布密度最大,孔径在4～7nm的孔体积占总孔体积的74.4%,孔径超过15nm的孔体积占总体积的10.8%。杨木应拉木中大量存在的中孔孔隙可归因于应拉木木纤维中的厚壁胶质层。

Based on the conventional anatomical analysis,the pore structures of poplar tension wood,such as specific surface area,pore volume and pore size distributions were characterized by nitrogen adsorption-desorption method.The shapes of the pores were estimated by nitrogen adsorption isotherms.The results show that poplar tension wood with BET specific surface area of 21.9 m2·g-1,which is 13 times higher than that in opposite wood.Poplar tension wood has intact mesoporosity（pore size between 2-50 nm） with inkbottle and slit shape pore,as well as a certain amount of micropores and macropores.The maximum value of pore size distribution appears at 5 nm.The pore volume with diameter ranging from 4-7 nm makes up 74.4% of the total,and larger than 15 nm,10.8%.The high amount of mesopores can be attributed to the thick gelatinous layer in poplar tension wood.