Study on the photodegradation behaviors of thermal-aged silk

In museums, silk cultural relics are highly sensitive to light. However, lighting is inevitable due to the exhibition needs, despite any light would pose irreversible damage to silk. Although the solution of eliminating UV radiation was widely achieved in museum lighting environment, long-time accumulation of other light sources still would induce photodegradation of silk. This work therefore established the simulated light ageing experiments to assess the degradation behaviors of silk samples with different ageing degrees. The variation of color values and structure transformation of each sample group were determined by the means of scanning electron microscopy (SEM), colorimeter, Fourier Transform infrared spectroscopy (FTIR) and 13C CPMAS NMR. The results indicated that silk samples with different initial ageing degrees presented different discoloration tendency and structural variation in experimental lighting environment, suggesting the higher disordered structure makes the silk more vulnerable to light damage. It is of great significance to understand the long-time impacts of illumination on degraded silk and further provide methodology for predicting the duration of exhibited silk cultural relics.