出土饱水梓木的辐射法保护

Radiation protection of waterlogged archaeological catalpa wood uncovered from Changtaiguan Xingyang

利用乙醇浓度梯度脱水、保护单体(PEG200DMA)逐级置换、60Coγ射线辐射固化(吸收剂量率为30.72kGy,剂量率90.35Gy/min)的方法对信阳长台关出土的棺木残片进行了试验性保护。保护后的试验样品外观颜色接近原文物,无开裂翘曲、无表面泛光和发黑现象、纹理清晰;顺纹压缩强度(33.06MPa)接近现代新材;保护前后相比的最大收缩率分别为:长度方向1.05%,径向4.10%,弦向4.32%;在常温常湿(温度:20～28℃,相对湿度:35%～65%)条件下贮存180d前后相比的收缩率分别为:长度方向0.076%,径向1.17%,弦向1.86%;在干燥环境(温度:(25±2)℃,相对湿度:(5±2)%)中贮存90d前后相比收缩率分别为:长度方向0.066%,径向0.115%,弦向0.279%;在高湿环境(温度:(25±2)℃,相对湿度:(5±2)%)中放置90天后的湿胀率与干燥环境相比分别为:长度方向1.79%,径向2.42%,弦向2.61%。微观结构研究表明:固化后的聚合物充满了残存饱水梓木内的毛细孔隙,提高了木材的力学强度和尺寸稳定性。

Waterlogged archaeological catalpa wood uncovered from Changtaiguan was tentatively treated by gradient dehydration of ethanol concentration, replacement of PEG200DMA gradually, and ^60Coγ-rays radiation curing with absorbed dose 30.72 kGy at dose rate 90.35 Gy/min. It can be found that the color and appearance of reinforced archaeological wood with clear texture looks like original one. There is no cracking, no warping, and no glare on the wood surface. The Compression strength of reinforced ancient wood （33.06 MPa） is close to that of modem Catalpa wood. The maximum linear shrinkage of reinforced ancient wood is 1.05% in grain direction, 4.10% in radial direction, and 4.32% in tangential direction respectively compared with that of original sample. The linear shrinkage under the condition of 180 days storage in the ambient temperature and humidity is 0.076% in grain direction, 1.17% in radial direction, and 1.86% in tangential direction respectively. The linear shrinkage under the condition of 90 days storage in the temperature （25±2） ℃ and relative humidity （5±2）% is 0.066% in grain direction, 0.115% in radial direction, and 0.279% in tangential direction respectively. The linear swelling ratio after 90 days storage in the temperature （25±2） ℃ and relative humidity （98±2）% is 1.79% in grain direction, 2.42% in radial direction, and 2.61% in tangential direction respectively. It is confirmed by microstmcture study that capillaries in residual wood has been filled with polymers, so that the wood mechanical strength and the shape stability is improved respectively.