Evaluation of the Stability of PVC Book Covers

When determining the state of deterioration of book covers made of softened polyvinylchloride, which is essential for the choice of conservation strategy, we are limited by the sample amount available for analytical evaluation. Infrared spectroscopy, as opposed to potentiometric titration, not always allows to unambiguously prove the decrease of sample thermal stability, nor the depletion of the stabilizer, the presence of which slows down dehydrochlorination and neutralizes released hydrogen chloride. For unplastized PVC samples, the time loss of weight determined by thermogravimetric analysis at 180 °C correlates with the amount of released hydrogen chloride obtained from potentiometric titration. The stability of the packages is closely linked to the history and handling of the books. It can be assumed that, with careful use and storing in the library depositories, book covers will remain functional for several decades.