PEG稳定河姆渡遗址出土香樟的干燥特性研究

研究饱水古木材的干燥特性可以对古木材的定型保护提供重要的参考,因此本研究以河姆渡遗址出土的香樟木材为试样,在加热的条件下,用不同质量百分比浓度的聚乙二醇(PEG 2000)为定形加固剂,研究了降解饱水香樟在自然条件下的干燥特性。结果表明降解饱水香樟的自然干燥过程可以分为干燥初期试样质量的快速下降和干燥后期试样质量平稳变化两个阶段。干燥初期试样质量下降比与干燥时间符合m/m0=-kt+c的干燥方程且线性良好。随着PEG处理浓度的升高,两个阶段之间逐渐出现一个过渡过程,PEG处理浓度越高,过渡过程越明显。达到干燥终点时,香樟试样的尺寸稳定性随着PEG浓度的升高而显著增强,当浓度达到70%时,纵向、径向和弦向的收缩率下降明显,但弦向的收缩率仍相对较大。随着PEG处理浓度的增加,自然干燥后的香樟试样表观色泽逐渐加深。因此,PEG 2000浓度以不超过40%为宜。

The drying characteristics of polyethylene glycolstabilized camphor tree excavated at the Homutu Ruins

Polyethylene glycol (PEG 2000) was used as bulking and consolidating agent to treat an archaeological camphor tree excavated at the Homutu Ruins. The excavated sample was used to study the drying characteristics of decayed, waterlogged wood in a natural environment. The results indicate that decayed, waterlogged archaeological camphor tree dries in two stages resulting in:a rapid mass decreases in the initial period and a steady slow mass decreases in the later period. In the initial period, the mass ratio m/m₀ and the natural seasoning time are in accordance with the equation m/m₀=-kt+c. The experimental data fits well with linear curve. A transition period exists between the two stages when the PEG 2000 concentration is increased. The higher the concentration of PEG 2000, the more obvious the transition process became and the size of the wood stabilized as the drying process approaches the end. When the PEG 2000 concentration reached 70%, the shrinkage rate of longitudinal and radial planes decrease significantly, but the shrinkage rate of tangential plane is still relatively significant. The color of the wood gradually deepens with an increase of PEG 2000 concentration.