明代袍服用丝绸面料的材质老化分析

Analysis on material aging of silk fabrics from a robe of the Ming Dynasty

采用形貌分析、红外光谱分析、热分析、氨基酸含量分析等方法对私人收藏的明代出土袍服面料进行纤维老化分析研究,并与现代桑蚕丝进行对比。研究结果表明:明代出土样品的桑蚕丝纤维直径较小且粗细不均匀,出现腐朽、脆断、劈裂的现象;其大部分红外吸收峰强度降低,如1 228 cm^(-1)处酰胺键III峰强减弱,3 277 cm^(-1)处特征吸收峰强度降低、峰位漂移等,说明桑蚕丝非晶区破坏、部分—CN键和肽链已经断裂,纤维发生老化。出土样品的热分析结果表明:热分解初期,出土样品的热分解温度高于现代桑蚕丝,桑蚕丝大分子的相对结晶度提高,无定形区受到破坏;同时出土样品的最大分解速率快于现代桑蚕丝,热分解温度范围比现代桑蚕丝小,是其大分子老化的表现;明代出土样品的甘氨酸含量比现代桑蚕丝高,说明其桑蚕丝非晶区老化严重,结晶区含量相对提高。文章为了解明代丝绸的老化现状及出土纺织品的保护提供参考。

Morphology analysis, infrared spectrum analysis, thermal analysis and amino acid content analysis were adopted to analysis the fiber aging of a private collection of unearthed robe fabrics in Ming Dynasty, and compared with modern silk. The results show that the silk fibers of Ming Dynasty has a small fiber size and uneven fineness with decay, brittle fracture and cleavage because of aging. The intensity of most infrared absorption peaks are decreased. For example, the intensity of peak amide bond III at 1 228 cm^-1 and characteristic absorption peak at 3 277 cm^-1 are decreased and the peak shift is taken place. It indicates that the silk amorphous region is destructed, the part of the —CN bond and the peptide chain is broken and the fiber is aged. The results of thermal analysis of the unearthed samples show that the thermal decomposition temperature of the unearthed samples is higher than that of modern silk during the initial stage of thermal decomposition, indicating that the relative crystallinity of the silk macromolecules is increased and the amorphous region is damaged. At the same time, the maximum decomposition rate of the unearthed sample is faster than that of the modern silk. The thermal decomposition temperature range of the unearthed sample is narrower than that of modern silk, which is the manifestation of macromolecule aging. The glycine content of unearthed samples in Ming Dynasty is higher than that of modern silk, which indicates that the aging of amorphous area of silk is serious and the rate of crystalline area is relatively increased.