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In the manufacturing process of the microfiber synthetic leather, various types of filling agents were selected to fill the microfiber synthetic leather base to improve the sanitary properties, in which a zirconium tanning agent was used commonly. In this study, the softness, moisture absorption, water vapor permeability and mechanical properties of the base were used as indexes, and the type and dosage of the filling agent were optimized. The results indicated that the sanitary properties of the base treated by the filling agent were improved generally compared with that of the blank base. Among them, the moisture absorption increased by 28–45%, the water vapor permeability increased by 50–56% and the mechanical properties were significantly improved. The bases before and after being filled were characterized by Fourier infrared spectroscopy, the water contact angle, atomic force microscopy, scanning electron microscopy and the specific surface area. The results showed that the filling agent’s cross-linking effect on the base fiber led to the active group content and wettability of the base increasing, the fiber surface structure changing obviously and the fiber gap becoming larger with looser dispersion. Moreover, the specific surface area of the base increased.

Published studies of silks focus on processed fibres or the optimum conditions for their production. Consequently, the effects of the environment on the physical properties of the cocoon are either poorly understood or kept as closely guarded industrial secrets. In this study, we test the hypothesis that silkworms as ectothermic animals respond to environmental conditions by modifying their spinning behaviour in a predictable manner, which affects the material properties of the cocoons in predictable ways. Our experiments subjected spinning Bombyx mori silkworms to a range of temperatures and relative humidities that, as we show, affect the morphology and mechanical properties of the cocoon. Specifically, temperature affects cocoon morphology as well as its stiffness and strength, which we attribute to altered spinning behaviour and sericin curing time. Relative humidity affects cocoon colouration, perhaps due to tanning agents. Finally, the water content of a cocoon modifies sericin distribution and stiffness without changing toughness. Our results demonstrate environmentally induced quality parameters that must not be ignored when analysing and deploying silk cocoons, silk filaments or silk-derived bio-polymers.

In this study, sodium alginate (SA) was oxidized with potassium periodate to produce an alginate-based tanning agent. Using OSA as a biodegradable tanning agent and a nano-hydroxyapatite (nano-HAp) low concentration suspension to give flame retardancy to leather, eco-design concepts were applied to establish a chrome-, aldehyde-, and phenol-free tanning process. Micro-DSC, 1H unilateral nuclear magnetic resonance (NMR), attenuated total reflection mode Fourier transform infrared spectroscopy (FTIR-ATR), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the complex matrix collagen-OSA-nano-HAp. Micro-differential scanning calorimetry (micro-DSC) was used to assess OSA’s ability to interact with collagen and stabilize the collagen-OSA matrix, while 1H unilateral (NMR) was used to investigate the aqueous environment and its limitations around collagen molecules caused by their association with OSA and nano-HAp. Industrial standard tests were used to assess the mechanical properties and fire resistance of the new leather prototype. The findings reported here indicate that both OSA and nano-HAp are suitable alternatives for cleaner tanning technologies and more sustainable leather.

•The carbon, nitrogen, hydrogen, and oxygen stable isotopic compositions of hair remain intact when polar bear skins are tanned.•The sulphur stable isotopic compositions of hair is slightly changed to more positive values as a result of tanning.•Stable isotopic information from the hair of preserved specimens can be applied to living animals.•Stable isotopic information contained in the hair of preserved wildlife skins may be used for forensic purposes. We investigated the effect of tanning on the stable isotopic compositions (CNHOS) of hair keratin. Samples of hair from polar bear (Ursus maritimus) hides were collected before and after the tanning process from a commercial tannery. With the exception of sulphur isotopes, tanning did not alter the stable isotopic compositions of hair. δ34S values were slightly more positive (1 per mil) in hair that had gone through the tanning process, likely as a result of the tanning agent, alum (Al2(SO4)3) or exposure to sulphuric acid (H2SO4). This indicates that, with the exception of sulphur isotopes, hair keratin is resistant to subsequent isotopic alteration by the techniques used in tanning of animal hides and thus the original stable isotopic information is likely to be preserved in archived samples, such as taxidermic mounts and museum specimens. This is an important consideration when dealing with ecological and forensic applications to wildlife, such as evaluating provenance or migratory reconstructions, and so will assist in conservation efforts and investigations of trafficking and poaching.

Recently, Acacia crassicarpa has been planted in peatland areas with acidic soil in Indonesia for use in pulp and paper materials. Its bark is not suitable to produce bleached pulp; hence, it is discarded as waste. Meanwhile, in South Africa and other countries, Acacia mearnsii has been planted for a long time, and its bark extracts have been used as a leather tanning agent. First, the structure of condensed tannin from the bark waste of A. crassicarpa is characterized. The yield of the extracts obtained from A. crassicarpa using a 70% acetone aqueous solution (7% based on bark weight) is less than that obtained from A. mearnsii (34%). A novel flavan dimer from the condensed tannin, specific to A. crassicarpa , is isolated from the bark extracts. To the best of our knowledge, this dimer is a new compound as evidenced from pyrolysis–gas chromatography–mass spectrometry and nuclear magnetic resonance analyses; it corresponds to a gallocatechin–catechin flavan dimer with the absence of one oxygen atom at the 3C of the pyran ring. In addition, 2,4,6-trimethoxybenzoic acid methyl ester is identified as a novel pyrolysis product obtained from the cleavage of the pyran ring.

The article is devoted to the investigation of the efficiency of chromium-modified montmorillonite dispersions to stabilize the collagen structure of the dermis. The interaction of modified dispersions of montmorillonite with collagen of the dermis was studied with the use of IR spectroscopic studies method. The high level of absorption of chromium compounds and their reduction by 30 % in the exhaust fluid was found. The use of montmorillonite dispersions provides qualitative formation of the structure of the dermis and physical and mechanical properties, with a reduction of tanning agents’ costs/waste by 16 %.

Leather plays a significant role in daily life due to its exceptional permeability, mechanical strength, and durability. However, traditional tanning processes not only lead to chromium pollution but also promote bacterial growth and yellowing. This study aims to develop an all green processing technology of multifunctional chromium‐free tanning agent (OKC‐EGDE) based on kappa‐carrageenan (KC), in which natural plant‐derived KC was pretreated by a green H₂O₂/Cu²⁺ oxidation system, followed by cross‐linking modification with ethylene glycol diglycidyl ether (EGDE). The aldehyde (–CHO) and carboxyl (–COOH) groups introduced during the oxidation process significantly enhance the antimicrobial properties of OKC‐EGDE. During tanning, these aldehyde and epoxy groups bind with amino and carboxyl groups on collagen fibers, leading to significant improvements in the mechanical properties of the tanned leather. Characterization results from FTIR, ¹H NMR, and XRD analyses indicate that the epoxy value of OKC‐EGDE is 0.37 mol/100 g, the oxidation value is 71%. Compared to traditional commercial chromium‐free tanning agents (TWS and F‐90), leather tanned with OKC‐EGDE exhibits superior mechanical properties (tensile strength: 17.5 MPa, elongation at break: 38.7%, tear strength: 55.6 N/mm), thermal stability, yellowing resistance, and biocompatibility. Meanwhile, the OKC‐EGDE has high antimicrobial rate of 99% against both Escherichia coli and Staphylococcus aureus . The degradation of tanning wastewater and life cycle analysis confirm that OKC‐EGDE‐tanned leather achieves full‐process environmental sustainability. This study demonstrates the significant application potential of natural plant polysaccharides and provides a new approach for sustainable and clean leather production.

Restrictions and control on the use of fatliquor especially the sulphited oil during leather production is required due to its effect on chromium change valence (from Cr(III) to Cr(VI)). Utilization of the other oil sources such as vegetable or mineral oil is worthed to be a substitute material. The aim of this study is to quantify the potential release of Cr(III) and Cr(VI) from different fatliquors and find the alternative fatliquor. The results showed that the use of 10% mineral oil and sulphited oil affected the Cr total and formation Cr(VI) in the leather, while using 6% condensed tannin (Mimosa) as an antioxidant is effective to reduce the Cr total and Cr(VI) contents in the leather.

The topic of hexavalent chromium (Cr(VI)) in leather has been debated throughout the whole supply chain for years. However, its significance has recently increased due to proposed changes in European legislation concerned with skin-sensitising substances suggesting that acceptable Cr(VI) concentrations in leather goods should be lowered from 3 mg kg−1 to 1 mg kg−1. The proposition of a stricter limit and current analytical difficulties created the need for a review of current standard test methods. The research presented in this paper investigates both the colorimetric (Part 1) and chromatographic (Part 2) methods under BS EN ISO 17075. The focus of the study was to identify possible sources of interference leading to large statistical variance in results and to define the limit of quantification with respect to the proposed new compliance limit. This study into the colorimetric method has shown that the presence of Cr(III), dyes, and proteins can be significant interferences, becoming critical at low Cr(VI) concentrations. Dilution factors worsen the problem of detecting low concentrations: a reliable quantitative detection of 0.01 mg kg−1 and 0.003 mg kg−1 Cr(VI) in solution are required at the 3 mg kg−1 and 1 mg kg−1 compliance limits in leather, respectively. BS EN ISO 17075 part 1 was shown to be incapable of reliably resolving to 3 mg kg−1 or below in leather. Part 2 shows a marked improvement in detection limits and reliability; however, data suggest that 1 mg kg−1 Cr(VI) is not reliably detectable in leather. Suggested improvements to the established test methods and a possible alternative are discussed.

Rice is a food crop which is grown in Indonesia widely and used as a staple food crop for filling domestic food needs. Rice husk is a solid waste that formed from rice grain milling. Along with the increase in national rice production per year, the rice husk also increase. There is silica content in rice husk have a potency that used as a tanning agent. It can be used as a material substitution of chrome sulfate as conventional tanning agent that have carcinogenic properties. This article will explain about tanning process, the potency of rice husk in Indonesia, rice husk utilization, and silica extraction process also nano-silica processing from rice husk. Besides that, it will describe silica and nano-silica usage in the tanning process, mechanism tanning nano-silica and leather properties that produced from the tanning process with nano-silica.