利用单边核磁共振研究樟子松木材干燥水分迁移规律

doi:10.11938/cjmr20233083

摘要/Abstract

摘要：

研究木材干燥过程中水分迁移可以更高效的利用木材．利用单边核磁共振技术（single-sided NMR）可沿木材不同方向进行一维测量的优势来探究木材在干燥过程中水分沿着轴向和弦向传递过程中不同测量深度的变化规律．本文以樟子松木材为研究对象，对其进行封胶处理使水分只沿着轴向或弦向传递，利用表观横向弛豫时间（T_2app）来探究其在干燥过程中不同测量深度位置处的含水率变化．结果表明：樟子松木材在干燥过程的前2 h其接近蒸发面处存在少部分自由水，之后在干燥过程中基本上不存在自由水，且靠近蒸发面存在明显的含水率梯度；水分沿轴向传递时越远离蒸发面，水分分布相对均匀，弦向传递时越远离蒸发面，每层水分差异越明显．单边核磁共振技术可以检测木材不同测量深度位置的含水率，可为研究水分在木材中的迁移机理提供理论依据．

关键词: 单边核磁共振, 木材干燥, 水分迁移, 表观横向弛豫时间（T_2app）, 迁移机理

Abstract:

Investigating the moisture migration during the wood drying process can help improve wood utilization. Single-sided nuclear magnetic resonance (NMR) technology facilitates such investigation with its advantage in conducting one-dimensional measurements along different directions of wood, allowing for the detection of moisture transfer at different depths along the axial and transverse directions during the wood drying process. This research focused on Pinus sylvestris var.mongolica wood, on which a glue sealing technique was employed to ensure that the moisture only transfers along the axial or transverse axis, and the apparent transverse relaxation time (T_2app) was utilized to delve into the changes of moisture content at various depths during the drying process. The results showed that at the first 2 hours of the drying process, there was a little free water near the evaporation surface of Pinus sylvestris var.mongolica wood, followed by a scarcity of free water during the drying process, and a noticeable moisture content gradient was observed near the evaporation surface. When the moisture transferred along the axial direction, the farther the moisture was away from the evaporation surface, the more uniform the moisture distribution was. When the moisture transferred along the tangential direction, the farther the moisture was away from the evaporation surface, the more obvious the moisture difference in each layer was. By single-sided NMR technology, it is possible to ascertain the moisture content of wood at various depths, thereby offering a theoretical framework for revealing the migration mechanism of water within wood.

Key words: single-sided NMR, wood drying, moisture migration, apparent transverse relaxation time (T_2app), migration mechanism

中图分类号:

朱晓风, 赵芝弘, 谭蕊, 周龙, 王一川, 刘文静, 张明辉, 刘化冰. 利用单边核磁共振研究樟子松木材干燥水分迁移规律[J]. 波谱学杂志, 2024, 41(2): 173-183.

ZHU Xiaofeng, ZHAO Zhihong, TAN Rui, ZHOU Long, WANG Yichuan, LIU Wenjing, ZHANG Minghui, LIU Huabing. Water Migration Characteristics of Pinus Sylvestris During the Drying Process Studied by Single-sided Nuclear Magnetic Resonance[J]. Chinese Journal of Magnetic Resonance, 2024, 41(2): 173-183.

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干燥时间/h	结合水		自由水
干燥时间/h	T_2app/ms	峰面积	T_2app/ms	峰面积
0	1.75	0.12114	37.6	0.47158
2	1.52	0.11594	37.6	0.41266
4	1.32	0.10656	37.6	0.32935
6	1.25	0.10434	37.6	0.22453
8	1.12	0.96945	37.6	0.13512
10	1.00	0.09549	32.7	0.07232
12	0.87	0.09338	32.7	0.02756
14	0.38	0.07289	12.3	0.01119
16	0.29	0.07008	11.5	0.01568