The effect of halloysite nanotubes dispersions on vegetable-tanned leather thermal stability

Abstract

Leather artefacts in historical collections and old leather bookbindings in archives and libraries frequently show a variety of visible changes which alter their appearance and ability to be used, such as powdery surface, weakened structure, complete or partial loss of the grain layer. However, historical leather stabilization and consolidation yet represent a challenging problem for conservators due to the sensitivity of collagen to the action of most of the conservation and restoration formulations currently used. In this paper we report our recent research concerning the development of halloysite nanoparticles dispersions for enhancing the hydrothermal stability of weakened historical vegetable tanned leather. The effects of halloysite nanotubes (HNTs) dispersed in various aqueous and non-aqueous mediums on the thermal stability of collagen in historical leather were tested using thermal microscopy, thermogravimetry and micro differential scanning calorimetry. Unilateral nuclear magnetic resonance was used to evaluate the changes in water dynamics due to collagen matrix interaction with dispersion media. The treated samples were also characterized using infrared spectroscopy and scanning electron microscopy. The analytical assessment confirmed the leather thermal stability increase and a partial recovery of fibres cohesion, thus validating the use of HNT dispersions as a basic tool for the preservation of collagen-based materials. Further functionalisation and encapsulation using antimicrobials, fungicides and pH adjustment nanoparticles will deliver novel and more durable HNTs-based conservation treatments.

Burial-induced deterioration in leather: a FTIR-ATR, DSC, TG/DTG, MHT and SEM study

“…In the last two decades, shrinkage temperature has been widely used as a metric for damage in old leather and parchment [23,[30][31][32][33] as well as to study the effects of various ageing or conservation treatments on leather and parchment [34][35][36][37][38]. Some of us have reported how leather hydrothermal stability, expressed as T f and T s , and structural cohesivity and heterogeneity, expressed as ΔC and ΔT, respectively, correlates with natural or artificially induced ageing patterns [18,25,33].…”

13C solid‐state NMR complemented by ATR‐FTIR and micro‐DSC to study modern collagen‐based material and historical leather

“…[11,[31][32][33][34] In addition, micro-DSC analysis provides quantitative results on the bulk material and unambiguously describes the deterioration state of historical leather identifying the key steps of deterioration process (i.e., thermal destabilisation of chemically modified and unmodified collagen, de-tanning, gelatinisation and irreversible denaturation). [35][36][37] The obtained results show that solid-state NMR spectroscopy is perfectly suitable for characterising the collagen-tannin complex in historical and archaeological vegetable tanned leathers.…”

“…Measurements were performed in the temperature range (15 to 95) C at 0.5 K min −1 heating rate using microsamples of about 2.0 mg as previously described. [35][36][37] One or two measurements were run for the historical samples due to the limited availability of samples. Experimental DSC data acquired with the SETARAM SetSoft2000 software were analysed with PeakFit 4.1 (Jandel Scientific) to obtain the specific calorimetric parameters of collagen thermal transition, while the PeakFit Gaussian algorithm was used to deconvolute the DSC multiple peaks of historical leather to identify the various collagen populations with different thermal stabilities.…”

Very Large Pore Mesoporous Bioactive Silicate Glasses: Comparison of Behavior toward Classical Mesoporous Bioactive Glasses in Terms of Drug Loading/Release and Bioactivity

“…To evaluate the influence on the interactions between nisin and the surface of silica when metals are present on the surface of the compounds, a TG_DTA analysis was performed (Figure 6). In the DTG graph, the first peak is related to the pyrolysis of nisin, and the second peak is related to the decomposition of the structure of nisin [46]. From derivative graphs obtained from TG (DTG), it is possible to notice that when gallium is preset on the surface, some interactions are promoted because the second peak is shifted to the right, and a third peak is present.…”