Determining the effect of finishing on leather structure using FTIR spectroscopy

This article investigates the influence of the leather finishing process on its structural properties using Fourier-transform infrared (FTIR) spectroscopy. The study involved a comparison of the infrared spectra of finished and unfinished leather samples. The measurements were carried out on a Shimadzu IRPrestige-21 FTIR spectrometer equipped with a Miracle accessory from Pike Technologies. Spectra for each sample were recorded in the range of 4000–400 cm⁻¹. The analysis was based on examining the main absorption bands (peaks) in the obtained spectra. The research was conducted in the "Structural and Biochemical Materials" engineering laboratory at the M. Auezov South Kazakhstan University. The results confirmed that the finishing process leads to a reorganization of chemical bonds and molecular changes in the material's surface layer. Specifically, it was established: formation of a polymer film on the surface of the samples, partial modification of the collagen structure and a reduction in the intensity of certain chemical bonds, a slight shift in the absorption bands of the amide group valence vibrations (–C=O, –NH) was observed, indicating a partial modification of the collagen chains. Thus, the obtained data prove that leather finishing causes a rearrangement of chemical bonds and molecular-structural changes in its top layer. The appearance of absorption bands in the range of 1735–1740 cm−1 on the surface of the finished sample indicates the formation of carbonyl (C=O) functional groups in its polymeric composition. Based on the results, further study and optimization of the composition of finishing materials are recommended to ensure the preservation of high quality and functional properties of leather.