Effect of UV Irradiation on Vegetable Tanned Leather

Abstract

EFFECT OF UV IRRADIATION ON VEGETABLE TANNED LEATHERABSTRACT. This article aims at studying the influence of UV irradiation on vegetable tanned leather. Vegetable tanned leather was treated in QUV chamber (T = 50°C, 2 irradiance = 1.77 W/mm nm, ë = 340 nm) for 0, 30, 60, 90, 120 and 150 hours. Then, these samples were evaluated by different analytical methods to get a whole UVA picture of the leather during the irradiation. Micro hot table (MHT), differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to evaluate the influences of UV irradiation on thermal behaviors. Damages to mechanical properties were also analyzed by a standard method. Fourier transform infrared spectroscopy (FT-IR) and optical microscopy were used to investigate the changes of structural and histological properties during aging process. With the extension of aging time, thermal stability was gradually reduced to lower values, including shrinkage temperature, thermal denaturation temperature, associated enthalpy and temperature for maximum decomposition rate. In addition, mechanical properties such as tensile strength, tear strength and elongation at break also gradually decreased. The FT-IR results showed that, during the aging process, amide I and amide II band of the tanned collagen gradually shifted to lower numbers, indicating an increasingly serious damage to the structure of the peptide chain, that corresponds to obvious fibril breakages which are also detected through optical microscopy. KEY WORDS: UV irradiation, vegetable tanned leather, aging INFLUENÞA IRADIERII UV ASUPRA PIELII TÃBÃCITE VEGETAL REZUMAT. Acest articol urmãreºte studiul influenþei iradierii UV asupra pielii tãbãcite vegetal. Pielea tãbãcitã vegetal a fost tratatã în camera QUV (T = 50°C, iradiere 2 = 1,77 W/mm nm, ë = 340 nm) timp de 0, 30, 60, 90, 120 ºi 150 de ore. Apoi, aceste probe au fost evaluate prin diferite metode analitice pentru a obþine o imagine UVA de ansamblu a pielii în timpul iradierii. S-au utilizat microplaca încãlzitã (MHT), calorimetria cu scanare diferenþialã (DSC) ºi termogravimetria (TG) pentru a evalua influenþele iradierii UV asupra comportamentului termic. Deteriorarea proprietãþilor mecanice a fost, de asemenea, analizatã utilizând o metodã standard. S-au utilizat spectroscopia în infraroºu cu transformatã Fourier (FT-IR) ºi microscopia opticã pentru a investiga modificãrile proprietãþilor structurale ºi histologice în timpul procesului de îmbãtrânire. Cu prelungirea timpului de îmbãtrânire, stabilitatea termicã a fost redusã treptat la valori mai mici, inclusiv temperatura de contracþie, temperatura de denaturare termicã, entalpia asociatã ºi temperatura vitezei maxime de descompunere. În plus, proprietãþi mecanice precum rezistenþa la rupere, rezistenþa la sfâºiere ºi alungirea la rupere au scãzut treptat. Rezultatele FT-IR au arãtat cã, în timpul procesului de îmbãtrânire, benzile amidã I ºi amidã II ale colagenului tãbãcit s-au deplasat treptat la numere de undã mai mici, indicând o deteriorare mai serioasã a stru...

Effect of Gamma Irradiation on the Stability of Tanned Leather

“…https://doi.org/10.31881/TLR.2024.038 The denaturation temperature of non-aged leather is higher than that of aged leather throughout the irradiation range except at a 30 kGy irradiation dose. This is because, during the photoaging process, collagen peptide chains may have been ruptured randomly, leading to the destabilization of collagen fibres [32] and, therefore, lower denaturation temperature. The decrease in denaturation temperature at 30 kGy irradiation dose for non-aged is attributed to the rupture of already formed crosslinks caused by gamma radiations [16,27].…”