不同干燥预处理对杨木应拉木孔隙结构的影响

采用CO<,2>超临界干燥、冷冻干燥和常规干燥对杨木应拉木和对应木进行干燥预处理,通过干燥前后试样的形变和吸附等温线,比较不同干燥预处理对杨木应拉木孔隙结构的影响,为定量表征应拉木的微观孔隙结构提供理论依据.结果表明:经CO<,2>超临界干燥的杨木应拉木具有完好的介孔特征(孔径在2～50 nm),BET比表面积和中孔体...

Effects of different drying pretreatments on pore structure of poplar tension wood

In order to compare the effects of different drying pretreatments(CO₂ supercritical drying, freeze drying and conventional drying) on pore structure of poplar tension wood, deformations of specimens before and after drying as well as nitrogen adsorption isotherms were measured, which would be expected to provide a theoretical basis for the quantitative characterization of micro-pore structure of tension wood. The results showed that poplar tension wood under CO2 supercritical drying had intact mesoporosity(pore size 2-50 nm). BET specific surface area and mesopore volumn were much higher than those of samples under freeze drying and conventional drying. Freeze drying and conventional drying could cause significant shrinkage deformations of specimens in longitudinal and tangential directions, while CO₂ supercritical drying could retain the porous texture quite intact by avoiding the pore collapse phenomenon induced by interface tension. CO₂ supercritical drying is suggested to be the best drying pretreatment to characterize the pore structure of tension wood.