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篇目详细内容 |
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【篇名】 |
Dynamic viscoelastic behavior of wood under drying conditions |
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【刊名】 |
Frontiers of Forestry in China(Ceased publication after completion of Volume 4 (2009)) |
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【刊名缩写】 |
Front. Forest. China |
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【ISSN】 |
1673-3517 |
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【EISSN】 |
1673-3630 |
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【DOI】 |
10.1007/s11461-009-0042-2 |
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【出版社】 |
Higher Education Press and Springer-Verlag |
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【出版年】 |
2009 |
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【卷期】 |
4
卷3期 |
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【页码】 |
374-379
页,共
6
页 |
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【作者】 |
Jiali JIANG;
Jianxiong LU;
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【关键词】 |
high-temperature drying; low-temperature drying; freeze vacuum drying; viscoelasticity; relaxation processes; micro-Brownian motion |
【摘要】 |
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In this study heartwood from a Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] plantation was treated using a high-temperature drying (HTD) method at 115°C, a low-temperature drying (LTD) method at 65°C, and freeze vacuum drying (FVD), respectively. The dynamic viscoelastic properties of dried wood specimens were investigated. The measurements were carried out at a temperature range of −120 to 250°C at four different frequencies (1, 2, 5, and 10 Hz) using dynamic mechanical analysis (DMA). We have drawn the following conclusions: 1) the storage modulus E＇ and loss modulus E＇＇ are the highest for HTD wood and the lowest for FVD wood; 2) three relaxation processes were detected in HTD and LTD wood, attributed to the micro-Brownian motion of cell wall polymers in the non-crystalline region, the oscillations of the torso of cell wall polymers, and the motions of the methyl groups of cell wall polymers in the non-crystalline region in a decreasing order of temperatures at which they occurred; and 3) in FVD wood, four relaxation processes were observed. A newly added relaxation is attributed to the micro-Brownian motions of lignin molecules. This study suggests that both the HTD and the LTD methods restrict the micro-Brownian motion of lignin molecules somewhat by the cross-linking of chains due to their heating history. |
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