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Leather Species Identification Based on Surface Morphological Characteristics using Image Analysis Technique 
by M. Jawahar, K. Vani and N. Chandra Babu
Volume: 111      Number: 8     Page: 308-314     Year: 2016
Identification and classification of leathers based on the species becomes valuable and necessary due to concerns regarding consumer protection, product counterfeiting or authenticity issues, and dispute settlement in the leather industry and thus helping in trading standards and protecting endangered species. This is carried out mostly by microscopical examination, though, the use of DNA fingerprinting is a theoretical possibility. Identification of leather species through hair pore pattern by microscopical examination requires expertise, training and experience, and due to involvement of human judgment, subjectivity is inevitable. Recent advancements in instrumental techniques aided image analysis offers a good scope for standardizing objective criteria for species identification. In this study, an automatic recognition of leather species based on the surface hair pore pattern using image processing techniques has been investigated. The signature or distinctive feature of leathers from each of the important raw materials dealt within the leather industry were defined from SEM images using image processing technique in terms of number of hair pores, pore density, type and size of the pores (in terms of area, diameter), inter-pore distance and shape of the pore (in terms of circularity, roundness perimeter). Results of the image analysis revealed that all the four common raw materials have distinctive features in terms of specific parameters. Buffalo leather is characterized by the least pore density, largest pore (11110 sq ́m) and highest inter-pore distance (103sq ́m) whereas sheep skin has the smallest hair pore (200 sq ́m) with lowest porosity. Goat skin has both medium (1256 sq ́m) and small sized pores (364 sq ́m) arranged in clusters with trios pattern arrangement and cow leather is characterized by large hair pore density (2262/sq cm) with more uniform mid-sized pores (2190 sq ́m). Thus the developed image processing technique using the current state of art has the potential to provide quantitative estimates of the leather surface morphological characteristics in terms of quantifiable parameters to identify the animal origin.
 
 
Leather Education - Preserving the Past...Investing in the Future 
by Rachel Garwood
Volume: 111      Number: 8     Page: 283-291     Year: 2016
“Challenges facing the leather industry” commonly include environmental legislation; the need for green chemistry, traceability, ethical sourcing and the list goes on. One issue that is crucial for the sustainability of the global leather industry and is often overlooked is “succession planning”. With large cohorts of employees due for retirement between now and 2020, the demand for quality leather graduates is ever increasing, placing a heavier reliance on higher education. In this review, the history, the present and the future of leather education are explored. What has driven the transition from “chalk and talk” to delivery via virtual space? With advanced information technology we are also facing a changing student and today’s student does not expect to be spoon fed the facts. Today, they have ready access to information on the Internet, so classroom delivery takes on a very different approach. Modes of delivery now incorporate social media, discussion boards, blogs alongside tutorials and seminars. The ability within education to address these changing demands and an understanding of the ever-changing market pressures will support the sustainability of our high value industry.
 
 
Development of Micro/nanocomposites with Antibacterial Effect for Leather and Textile 
by A. Bacardit, C. Casas, J. Bou and L. Olle
Volume: 111      Number: 7     Page: 267-275     Year: 2016
The aim of this work was to develop new systems of micro/nanocomposites to confer new functions to materials used for seats of public vehicles and public spaces. Specifically, this study focuses on antibacterial effect for leather and technical textile substrates. The first stage of the research consists of a selection of micro/ micro/nanomaterials and active principles: selection and evaluation of micro/nanoparticles, antibacterial and antifungal substances. In the second stage, the process of encapsulation of active principles was studied. The research includes optimization of the encapsulation process by improving the size and stability of the capsules. In addition, the synthesis of a hybrid organicinorganic polymer acting as a micro/micro/nanomaterial carrier was developed. To understand the mechanisms of synthesis and action of micro/micro/nanomaterials, characterization techniques have been used: scanning electron microscopy SEM and optical microscopy, analysis and distribution of particle size (DLS, Zetasizer). Regarding the antibacterial and antifungal ability of micro/nanocomposites, we adapted standard ASTM 2180-07 “Test methods for determining the activity or incorporated antimicrobial agent (s) in polymeric or hydrophobic materials.” Different products have been developed and the results obtained allow us to conclude that the synthesized products showed inhibition to the growth of bacteria and fungi on the contact surface.
 
 
Performance of Microbicides for the Preservation of Vegetable Tanned Leather 
by J. Fontoura, D. Ody and M. Gutterres
Volume: 111      Number: 7     Page: 259-266     Year: 2016
In the tanning industry, the deterioration of leather due to the development of fungi is of great concern. Some fungi metabolize important substances in leather, causing serious damage such as pigmented stain that is difficult to remove, defects, surface roughness, and loss of physical and mechanical resistance, which affect the quality of the final product. This work evaluated the performance of five microbicides conventionally used in the leather industry, against different fungi. Microbicides were applied during the tanning process with vegetable tannin in the fatliquoring step. Accelerated microbiological tests (plating and tropical chamber) were performed. The results revealed a low antifungal capacity of selected microbicides when applied at an offer of 0.2% (mass hide base) fungicides. Treatment with OIT+BMC/water at an offer of 0.75% showed satisfactory fungal protection against different fungi tested and proved to be the most suitable for the preservation of vegetable tanned leather.
 
 
Use of Ternary Solvent (Water - Ethanol - Ethyl Acetate) Medium for Leather Processing: A Possible Paradigm Change 
by B. Gari, S. Fessehaye, R. Aravindhan, K. Sreeram, J. Raghava Rao and B. Unni Nair
Volume: 111      Number: 7     Page: 250-258     Year: 2016
An attempt to replace water (7-10 m3/ton) in leather processing with a ternary mixture of solvents that would have a lower boiling point than water (for easy recovery through evaporation) and also bring about maximum solubility of conventional dyes, syntans and fatliquors is reported. The ternary mixture (Water – ethanol – ethyl acetate) reported in this study provided for good solubility/dispersion of leather chemicals. Average particle size of the syntan/dye in solvent / water remaining the same, particle size distribution of dyes and syntans was advantageous in the solvent medium, leading to better diffusion. Amongst various trials, neutralization of the leathers after tanning in solvent medium followed by use of neutralization syntans was found to be more advantageous to obtain leather properties comparable to conventional controls. The adsorption studies of dye used in the present study followed Freundlich model in both solvent and water medium indicates multilayer adsorption. Physical properties of the leathers were similar to that of control, indicating clearly that the solvent had no adversary effect on collagen and also provided for good diffusion and fixation of chemicals. The method thus reported in this study could provide for a minimum change approach to leather processing with ample contribution to water saving.
 
 
Effect of pH on A1/Zr-Binding Sites Between Collagen Fibers in Tanning Process 
by Shan Cao, Yunhang Zeng, Baozhen Cheng, Wenhua Zhang and Bing Liu
Volume: 111      Number: 7     Page: 242-249     Year: 2016
In this article, near infrared reflection (NIR) spectra were employed to investigate the pH influences on binding behaviors of collagen fiber (CF) towards conventional non-chrome inorganic salts (Al and Zr). Based on the analyses of NIR and corresponding 2D NIR spectra, the binding capacity of Al (or Zr) contributed by each type of functional groups on CF was successfully evaluated at different pH conditions by carried out the aluminum tanning (or zirconium tanning) to native CF deaminated collagen fiber (DACF) and decarboxylated collagen fiber (DCCF), respectively. Our experimental results indicated that, for aluminum tanning, both the carboxyl group and amino group of CF are the active sites responsible for Al-binding and the reactivity of carboxyl group to aluminum is higher than that of amino group. However, the amino binding sites are more influenced with different pH. As for zirconium tanning, amino group and carboxyl group are still the active binding sites while the reactivity of amino group is higher than that of carboxyl group in the pH range of 0.5~1.5 which increases with the increasing tanning pH. Furthermore, based on the analysis of Fourier transform infrared spectra of polycaproamides reacted with zirconium at different pH, it was found that the amide group in collagen is responsible for Zr-binding between collagen fibers and its reactivity with zirconium increases with the rise in pH.
 
 
Effect of Sodium Chloride on Structure of Collagen Fiber Network in Pickling and Tanning 
by Xinxin Li, Ya-nan Wang, Jing Li and Bi Shi
Volume: 111      Number: 6     Page: 230-237     Year: 2016
Tannery wastewater usually contains a high salinity due to the use of sodium chloride (NaCl) in curing and pickling. Although some no pickle tanning and salt-free pickling technologies were developed, few of them have been widely used due to relatively poor mechanical and bulk properties of the resultant leathers. Therefore, the role of NaCl in pickling and tanning should be investigated in the first place. In this study, bated pelts were pickled by salt-free pickling and conventional salt-assisted pickling processes, respectively, and then tanned by chrome tanning agent. The hierarchical structures of collagen fiber network of the pickled pelts and leathers were observed by optical microscope and SEM, while the porosity of leathers was measured. The results showed that the fiber bundles of the pelt pickled in the presence of NaCl were more sufficiently dispersed compared with those of salt-free pickled pelt. Both of the chrome tanned leathers had a regular arrangement of collagen fibers, but the leather with salt assisted pickling presented remarkably higher degree of fiber dispersion, as well as larger porosity. Moreover, the role of NaCl in organic tanning using an amphoteric organic tanning agent was investigated. The results also showed that the presence of NaCl in tanning could improve the opening up of collagen fiber network and the porosity of the leather. In general, NaCl used in leather processing presented a positive effect in consideration of leather quality.
 
 
Performance of Antimicrobial Agents for the Preservation of Chrome Leather 
by J. Fontoura, D. Ody and M. Gutterres
Volume: 111      Number: 6     Page: 221-229     Year: 2016
Fungal growth in leathers causes significant damages like stains, surface roughness and loss of physical-mechanical resistance. This raises the need to develop control strategies by the use of antimicrobial agents. Considering the improving processes with regard to the use of antimicrobial agents added in skins and leathers to prevent their contamination by fungi, this study aims to evaluate the performance of six antimicrobial agents conventionally used in the leather industry, against four different fungi. These agents were applied during the chrome tanning process. Accelerated microbiological assays (tests plating and incubation on tropical chamber) were performed, as well as sorption and wash-out testing of three selected antimicrobial agents by UV/VIS spectrophotometry and verification of surface biodeterioration through SEM. Antimicrobial agents 2-thiocyanomethylthio benzothiazole (TCMTB) and Aqueous dispersion of 2-n-octyl-4-isothiazolin-3-one + methyl Nbenzimidazol- 2-ylcarbamate (OIT+BMC/water) showed antifungal capacity against different fungi tested applied in concentration of 0.2% (weight leather base). In the tropical chamber test, for the five samples of wet-blue leather treated with antimicrobial agents the growth of fungus was not observed. From the antimicrobial agents subjected to sorption testing and wash out, the TCMTB based antimicrobial agent presented rapid and high sorption in wet blue leather and also has resistance to washing.
 
 
An Examination of Antimicrobial Activity of Lining Leathers Fatliquored with Essential Oils 
by E. Bielak, E. Marcinkowska, J. Sygula-Cholewinska and J. Golnka
Volume: 111      Number: 6     Page: 213-220     Year: 2016
To prevent losses caused by microbiological decay of leathers during technological processing, biocidal and biostatic chemical agents are used. They are introduced into the material structure at various stages of the tanning process. It has been shown that some of these agents are not neutral to human health and to the environment. Thus, substitutes for chemical preparations of appropriate efficiency in control of bacteria and fungi, but being safe to humans and the environment are sought. Suitability has been adequately confirmed by research performed worldwide on essential oils. In this paper antimicrobial resistance of lining leathers protected with essential oils extracted from plants Cinnamomum verum, Eucalyptus globulus, Origanum vulgare, Leptospermum scoparium and Thymus vulgaris is investigated. They were introduced into the leather at the fatliquoring stage at 5% per weight of leather. Antimicrobial activity of samples oiled with essential oils and controls (without these oils) was evaluated against bacteria Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and yeasts Candida albicans after 1 and 6 months. The growth inhibition zone around leather samples and microorganism growth, or lack of growth, within the sample-medium contact zone was determined. Investigations have confirmed the efficiency of three of five proposed oils: oregano, cinnamon and thyme. The strongest and most longlasting antimicrobial activity was observed for leathers preserved with oregano oil. Insufficient effect was found for leathers oiled with manuka and eucalyptus oils.
 
 
Effect of Different Unhairing Methods on the Ionic Liquid Based Fiber Opening Process 
by M. Azhar, G. Jayakumar, J. Raghava Rao and N. Fathima
Volume: 111      Number: 6     Page: 206-212     Year: 2016
Leather processing is known to impact the environment, especially the pre-tanning processes. Lime sludge is one of the major concerns for the industry. Application of ionic liquid (1- butyl 3- methylimidazolium chloride) instead of conventional reliming practice can reduce this problem to a large extent. In this study, the effect of different unhairing process on the fiber opening using ionic liquids has been studied. The extent of fiber opening was assessed for both control and experimental pelts through SEM analysis. The experimental pelts were found to have better fiber opening than the control. The ionic liquid fiber opened pelts were tanned and the spent liquors were assessed for the chrome content, COD, TDS. The results indicate that all the environmental parameters are better or on par with the conventional process. The final leathers made were also found to have physical characteristics similar to that of conventionally limed leathers.