Towards non-destructive evaluation of plasticized polyvinyl chloride in modern design heritage objects

Plasticized poly(vinyl chloride) (PVC-P) is widely present in cultural heritage collections but is inherently unstable due to dehydrochlorination and plasticizer migration, making assessment of the degradation of PVC-P-based objects essential for establishing appropriate storage and display conditions to maximize their lifetime. This study investigates PVC-P degradation using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) on artificially aged model samples and naturally aged objects. ATR-FTIR monitored changes in bands associated with C–Cl and C = O vibrations, with decreasing absorbance consistent with dehydrochlorination and plasticizer loss, respectively. More advanced degradation was consistently observed at surfaces exposed to the surrounding environment. Similar trends were found in naturally aged objects and artificially aged samples. SEM–EDS analysis showed decreasing Cl/C ratios at the outer surface in agreement with the ATR-FTIR results, while interpretation of changes in O/C ratios was more complex due to the contribution of different oxygen-containing species. Differences between outer and inner surfaces increased with aging time in the model samples and with object age in naturally aged objects, while ATR-FTIR spectroscopy additionally revealed increasing material heterogeneity during degradation.