氮气吸附法评估杨树无性系木材细胞壁孔隙结构  

Examination of pore structure in wood cell walls of poplar clone using nitrogen adsorption

作　　者：赵婉婉 梁睿 张耀丽 ZHAO Wanwan;LIANG Rui;ZHANG Yaoli(College of Materials Science and Engineering,Nanjing Forestry University,Nanjing 210037,China)

机构地区：[1]南京林业大学材料科学与工程学院,南京210037

出　　处：《林业工程学报》2022年第3期80-85,共6页Journal of Forestry Engineering

基　　金：国家重点研发计划(2017YFD0600202);国家自然科学基金(31670558)。

摘　　要：杨树无性系作为人工林的重要树种有着宝贵的科研和实用价值,对杨树无性系木材细胞壁进行孔隙结构分析,可以深入研究杨木品种的异同。利用氮气吸附法研究了8个品种的杨树无性系木材绝干状态下细胞壁孔隙结构的异同,采用BET模型与BJH模型对其孔隙结构的比表面积、孔容与孔径分布进行了分析,研究发现:8个无性系样品的氮气吸附-脱附曲线重合度很高,均没有出现明显的滞后环,说明8个杨树无性系木材普遍存在类似的孔隙结构和孔容分布。8个样品整体氮气吸附量较少,为1.8~5.4 cm^(3)/g,比表面积为1~5 m^(2)/g。杨树无性系木材的微孔孔容最小,约占整体的3%,而10~50 nm的介孔最多,超过30%。在一定程度上,高氮气吸附量带来高孔容。这与杨木的特征有关,孔隙的数量越多,形成的孔洞体积越大。比表面积则更多受到孔径10 nm以下孔隙的影响,未见10 nm以下孔隙是造成36号杨低比表面积的原因。同样的,由于没有10 nm以下的孔隙,36号杨的平均孔径极高,约54.79 nm,远高于其他杨树无性系木材的7~17 nm。As an important tree species in plantations,poplar clone has great values for scientific research and practical application.Porosity is an important feature of wood and has significant influence on wood physical and mechanical properties.The pore structure analysis of the cell wall of the poplar clone can deeply investigate the similarities and differences of poplar wood species.At present,the electron microscopy technology cannot directly image the microscopic pores of wood cell walls at the nanometer level.Therefore,gas adsorption methods are often used to obtain pore information.This study used nitrogen as the adsorption medium to measure mesopores with the diameter of 2-50 nm.The nitrogen adsorption method was used to examine the similarities and differences of the pore structure of eight types of poplar clones which were oven-dried.The BET model and BJH model were used to analyze the specific surface area,pore volume and pore size distribution.It was found that,after the eight samples completed adsorption and desorption processes,the curves were smooth,so the test results were valid and credible.The nitrogen adsorption-desorption isotherms curves of the eight samples had a high degree of coincidence,and there was no obvious hysteresis loop,indicating that the eight poplar clones generally had similar pore structure and pore volume distribution,and the shape of the pores had no special orientation.The overall nitrogen adsorption capacity of the eight samples was relatively small,ranging from 1.8-5.4 cm~3/g,and the specific surface area was between 1-5 m~2/g.The micropore volume of the poplar clone wood was the smallest,accounting for about 3% of the total,and most samples showed a small peak at 5 nm.The 10-50 nm mesopores were the most,exceeding 30%.To a certain extent,high nitrogen adsorption capacity brought high pore volume,which was related to the characteristics of poplar wood.The larger the number of pores,the larger the volume of pores formed.The specific surface area was mostly affected by pores with

关 键 词：杨树无性系木材 氮气吸附 细胞壁孔径 比表面积 孔容分布 

分 类 号：S781.3[农业科学—木材科学与技术]