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

Abstract

In this study we used an analytical approach based on complementary techniques that targets all structural levels of collagen in leather to investigate how vegetable-tanned leather deteriorates during soil burial tests. For the first time, a group of deterioration markers specific to molecular, fibrillar and fibrous structure of collagen in leather was associated with the deterioration of buried leather. The application of the second order derivative of FTIR-ATR spectra analysis allowed us to detect loosening of collagen–tannin matrix, de-tanning and gelatin formation based on the behaviour of collagen and tannin spectral components (intensity variation and shifts). Collagen denaturation observed by DSC analysis and its thermo-oxidative behaviour measured by TG/DTG analysis, as well as the altered morphology of collagen (namely melt-like fibres and distorted fibrillar ultrastructure) imaged by SEM confirmed the FTIR-ATR analyis results. These analytical outcomes enabled us to understand the effect of leather hardening/cementing through soil mineral penetration into its fibrous structure and thus correctly interprete the higher-than-expected shrinkage temperatures and intervals determinatd by MHT method. Thus, MHT method proved to be suitable for a quick evaluation method that can direcly support the first conservation decision after excavation. The combination of FTIR-ATR, DSC, TG/DTG and SEM can be particularly useful to provide insights on the deterioration mechanism of archaeological leather and support best decision on its long-term preservation.

Leather-like composite materials prepared from natural rubber and two leather wastes: Wet blue leather and finished leather

“…The WBL (Figure 2(a)) and inner side FL (Figure 2(b)–(d)) shows the same characteristic spectra appeared at 3300 cm −1 assigned to O-H stretching of moisture, 32 1633 cm −1 attributed to N-H bending of amide I complex and reflected chromium with carboxylate groups (-Cr-OOC-), 32,33 1550 cm −1 attributed to the combination of the N-H bending or C-N stretching of amide II and including chromium interaction with amino groups (-Cr-NH-), 32,33 1450 cm −1 attributed to the CH 2 bend of phospholipids, 32,33 and 1240 cm −1 attributed to the N-H bending of amide III. 32,33 In addition, the top grain FL in Figure 2(e)–(g) observed spectra at 1729 cm −1 corresponds to C=O of from fat liquoring products that typically used in final step of leather finishing, 34,35 1645 cm −1 associated to N-H bending of amide I, 32,33 sharp spectra at 1278 cm −1 associated to N-H deformation and C-N stretching, 36 broad spectra in the range of 1100-1000 cm −1 corresponding to monomeric chromium stretching (-Cr=O-), 37 and strong spectra at 840 cm −1 also related to Chromium vibration (-Cr-O-Cr-). 37

Figure 2.ATR-FTIR spectra of (a) WBL and (b)–(g) various FL.

Figure 3.ATR-FTIR spectra of the samples (a)–(e) and thermal aged samples (f)–(j) of NR and NR_WBL.

Figure 4.ATR-FTIR spectra of the samples (a)–(e) and thermal aged samples (f)–(j) of NR and NR_FL.

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“…Moreover, the WBL-filled NR composites demonstrated higher hardness than the FL-filled NR composites when compared at the similar loading levels due to softening effect of fatty acid at the final stage of FL manufacturing. 34,35

Figure 5.Shore A hardness of the samples.

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Identification of surface dyeing agents of two bookbinding leathers from 19th‐century Qajar, Iran, using LC–MS, μXRF and FTIR spectroscopy

“…These two peaks are assigned to thermal denaturation of the crystalline phase collagen embedded into an amorphous matrix. However, similar to the two samples studied, these two peaks can disappear due to collagen degradation (Vyskočilová et al, 2022). Therefore, the second derivative of the DSC curves was investigated to identify weak peaks.…”

“…DSC curves and their second derivative are presented in Figure 8. According to Vyskočilová et al (2022), the DSC curves for the new leathers displayed a broad endotherm peak ranging from room temperature to about 120°C, related to the dehydration process. In addition, there are two small endotherms peaks at the temperature of about 140°C (T d1 ) and 230°C (T d2 ).…”

Cross-Linked Collagen-Based Scaffold: Anti-infective Potential, Hydrophilic, and Biocompatible

“…In collagen-related studies, FT-IR was generally used for molecular changes in its secondary structure . As shown in Figure d, the main component of pADM was type I collagen, and its special structures, amide I, II, and III bands and amide A and B bands, were clearly characterized in the FT-IR spectra, which were directly determined by the internal structure of the collagen molecule.…”