16/10/2015

“Thermal characterization of new, artificially aged and historical leather and parchment” by Sebestyén et al (2015)

Sebestyén, Zoltán; Czégény, Zsuzsanna; Badea, Elena; Carsote, Cristina; Şendrea, Claudiu; Barta-Rajnai, Eszter; Bozi, János; Miu, Lucretia; Jakab, Emma; “Thermal characterization of new, artificially aged and historical leather and parchment”, Journal of Analytical and Applied Pyrolysis 115 (2015) pp.419–427.
DOI:10.1016/j.jaap.2015.08.022 (ScienceDirect, restricted access)

Abstract:
The aging mechanism of leather and parchment was studied by thermoanalytical methods to understand the effect of the environment on the historical manuscripts and the heritage of libraries and archives. Alkaline and acidic treatments followed by thermal dehydration were applied to achieve chemical changes in the structure of new leather and parchment similar to the slow natural aging of historical samples. Chemical and structural changes during both natural and artificial aging processes were characterized by thermoanalytical techniques. The thermal stability and the evolution profile of the decomposition products under slow heating were studied by thermogravimetry/mass spectrometry (TG/MS). The distribution of the decomposition products of these collagen-based materials under fast pyrolysis was characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). It was found that the maximal rate of the thermal decomposition (DTGmax) significantly decreases by aging in case of both leather and parchment samples indicating the degree of deterioration. Py-GC/MS has been found to be a suitable technique to sensitively monitor the degradation of the polyphenolic components of the vegetable tannins under natural or artificial aging. It was established that the tannin content of leather is more significantly affected by natural aging and alkaline treatment than the main structure of the polypeptide chains. Principal component analysis (PCA) has been used to find statistical correlations between the experimental data for leather samples. The results of the PCA confirmed that the alkaline treatment and the natural aging processes similarly modify the tannin content of the vegetable tanned leather.