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Development of Alginate-Chitosan Based Biopolymers for Leather Retanning 
by R. Aravindhan, K. Sreeram and J. Rao
Volume: 109      Number: 4     Page: 99-109     Year: 2014
Hides and skins when received in tanneries have closely and firmly packed together bundles of collagen fibers, with elastin and other non-fibrous proteins aiding a dense structure formation. However, in order to ensure the easy diffusion of chemicals, a series of pre-tanning operations ensure the opening up of the fiber bundles and the removal of the non-fibrous materials, resulting in a loose structure. A majority of leather consumers often demand properties, which were available on hides and skins, but lost during the pre-tanning operations. One such property is the compaction or firm packing of fiber bundles. While vegetable tanning processes provide for good fullness and firm packing of fiber bundles, the lack of strength and stability against wet heat forces the tanners to adopt chrome tanning. Chrome tanning provides for good inter and intra networking of fibers, but is unable to replenish the firmness found in the original raw material. To overcome this drawback, tanners often resort to the use of a combination of retanning agents in varying proportions. The varying character of these products results in non-uniform and poorer uptake. In this work an attempt has been made to develop syntans from biopolymers such as chitosan and alginate, which could provide fiber compaction to the leather.
 
 
The Role of Neutral Salt for the Hydrolysis and Hierarchical Structure of Hide Fiber in Pickling 
by Haiming Cheng, Min Chen and Zhiqiang Li
Volume: 109      Number: 4     Page: 125-130     Year: 2014
Pickling process carried out for adjusting the skin to the desired pH for tanning, in which neutral salts were added to avoid skin fiber from the acid swelling. This research study aimed at investigating the contribution of neutral salt to the hydrolysis and the fibrous structure of collagen fiber in acid solutions. Collagen fiber and bovine hide in sulfuric acid solutions with sodium chloride or sodium sulfate were investigated. The total protein concentration in the solutions was determined. The hierarchical structures of bovine hide in different acid and neutral salt systems were investigated by optical microscope, TEM and SEM. This study suggested the importance of neutral salt for the hydrolysis and the dispersion of collagen fiber in pickling. It implied that the osmotic swelling by acid could not reach the inner scale of fibril. The decrease in mechanical properties for the leather tanned with salt free pickling may have been caused by osmotic swelling destroyed the interactions among the fibril and fiber bundles.
 
 
New Challenges in Chrome-free Leathers: Development of Wet-bright Process 
by A. Bacardit, S. Van der Burgh, J. Armengol and L. Olle
Volume: 109      Number: 4     Page: 117-124     Year: 2014
The aim of the present work was to develop a new tanning process (wet-bright) that produces perfectly white leather meeting all of the requirements for many kinds of articles, such as automotive, garment and shoe upper. This new process gives leather that is free of chromium, aldehydes, aldehyde precursors and organic solvents. It is the application of a new system based on a product designated Tanfor TTM from the manufacturer Kemira. When compared to existing traditional wet leather processes, there are economic and environmental advantages resulting from the use of this new system. Also, the mineral character of the new product system offers leathers with high dye affinity; thus enabling very bright colors in all leather applications. We believe this leather offers such perfect dyeing properties because of the brilliant whiteness of the wet-bright intermediate substrate.
 
 
Sustainability in Process Innovation: Development of a Green Tanning Process Supported by LCA Methodology 
by M. Puccini, M. Seggiani, D. Castiello and S. Vitolo
Volume: 109      Number: 4     Page: 110-116     Year: 2014
As a response to the growing concerns about a variety of environmental issues expressed by public opinion and political bodies, the leather industry needs to support its market by environmental criteria as a guarantee of quality. For this reason, assessment tools as Life Cycle Assessment (LCA) methodology, which allow a more thorough knowledge of the products to the enterprises and can help to guide the environmental policies, are recommended (e.g. EC Directive on Ecologic Labels). The LCA methodology, described in details by the ISO 14000 series, allows the assessment of the environmental impacts due to products, processes, or services, by the identification of the inputs (e.g. energy and material consumption) and outputs (e.g. waste and pollutant production) streams exchanged by the process with the environment (i.e. from raw materials procurement to waste streams disposal). The application of LCA as tool for integration of sustainability aspects in process design and development is gaining wider acceptance and methodological development. In this study, the life cycle modeling was used to support the development of a novel tanning process based on the use of a new class of tanning agent produced from renewable resources (e.g. glucose). The experimental activity performed to investigate the technical feasibility of the innovative tanning cycle was supported by the modelling of the process using the LCA methodology in order to assess the environmental performance of the leather production cycle. Therefore, an LCA analysis was performed in order to compare the glucose-tannage process with the traditional one from an environmental point of view.
 
 
Improvements in Leather Surface Hydrophobicity through Low-pressure Cold Plasma Polymerization 
by Ya-e Feng, Xuepin Liao, Yanan Wang and Bi Shi
Volume: 109      Number: 3     Page: 89-95     Year: 2014
Vinyltriethoxysilane (VTES) was polymerized and deposited on the surface of upholstery crust leather by using low-pressure cold plasma technology. After plasma treatment (50 W, 300 s), the initial water contact angle of the leather surface increased from 120o to 140o, showing a significantly improved hydrophobicity of leather surface. The increased hydrophobicity of leather surface could remained even the leathers were stored for 240 d. The surface morphologies of leather were characterized by Scanning Probe Microscope (SPM) and Scanning Electron Microscope (SEM). Unlike the fiber-like texture of untreated leather, a coating of VTES polymer on the plasma treated leather surface was observed by SPM. SEM and SPM images indicated that this coating film was on the surface of collagen fibers rather than the whole surface of leather, which would not reduce permeability of air and water vapor of the leather. Energy Dispersive X-ray Spectroscopy (EDS) was performed to determine the chemical composition of leather surface. The contents of Si and O increased remarkably as leather surface was covered with polymerized VTES. The X-ray Photoelectron Spectroscopy (XPS) showed that the peaks attributed to C=C bonds of VTES and C=O bonds of collagen disappeared after plasma polymerization. All these results demonstrated that VTES was polymerized and deposited on the surface of collagen fibers after plasma treatment, which resulted in a hydrophobic surface of leather.
 
 
Biopolymers Produced from Gelatin and Whey Protein Concentrate Using Polyphenols 
by M. Taylor, J. Lee, L. Bumanlag, R. Latona and E. Brown
Volume: 109      Number: 3     Page: 82-88     Year: 2014
Several researchers have recently demonstrated the feasibility of producing biopolymers from the reaction of polyphenols with gelatin in combination with other proteins (e.g. whey) or with carbohydrates (e.g. chitosan and pectin). These combinations would take advantage of the unique properties of both species and at the same time create products with enhanced functional properties. We have successfully demonstrated that the polyphenolic gallic acid and the vegetable tannins quebracho and tara could be used to modify gelatin and whey protein concentrate (WPC) resulting in a subsequent change in the physicochemical properties of each. When gelatin-polyphenol products were used as fillers, considerable improvements were seen in the subjective properties of the leather and when compared to control samples, there was no significant impact on mechanical properties. In this continuing research, we have begun to evaluate the potential of tara-modified gelatin/WPC biopolymers, specifically for their application as fillers. In this study, modification parameters for gelatin/WPC combinations will be explored, and the results of product characterization using physicochemical analyses will be presented. These studies could further contribute the use of sustainable resources in production of unique products that may have leather processing applications.
 
 
Studies on Ethiopian Sheep Skins as an Opportunity for Value Addition Part I: Histological, Microscopic and Chemical Characterization of Abyssinian and Wanke Sheepskins 
by H. Mohammed, G. Aysanew, R. Aravindhan, A. Gnanamani, J. Rao and N. Chandrababu
Volume: 109      Number: 3     Page: 76-81     Year: 2014
The leather industry is one of the priority sectors in Ethiopia, which has been identified as potentially competitive in the global market. Ethiopian tanners face a shortage of raw material input for production of leather. The government strategically planned for importing raw skins from neighboring countries and also for effective utilization of available raw material resources in the country. About fourteen sheep breeds are recognized in Ethiopia. Among the available resources, Wanke sheepskins, indigenous to lowland of Ogaden area of Somali Region take prime position based on their availability. Meat of Wanke sheep is in high demand in international market, but the skin commands low price not only due to availability but also less demanded by tanners due to natural problems associated with the skin. In this paper the histological, chemical and physical characteristics of Wanke sheepskins have been analyzed using various tools and techniques. This characteristic understanding of the Wanke sheepskins will enable the development of process strategy to produce Wanke leathers with improved properties.
 
 
Effects of Thickness and Gain on the Amplitude of Airborne Ultrasonics 
by C.K. Liu and N. Latona
Volume: 109      Number: 3     Page: 70-75     Year: 2014
Currently, hides and leather are visually inspected and graded for quality, usable area, and sale price. However, visual inspection is not reliable for detecting defects that are hidden inside the material. Development of a non-contact nondestructive method to accurately evaluate the quality of hides and leather is urgently needed. We previously reported the research results for airborne ultrasonic (AU) testing using non-contact transducers to evaluate the quality of hides and leather. The ability of AU testing was demonstrated for revealing defects in hides and leather that were difficult to be found during visual inspection. We also reported results on AU inspection using a statistical data/cluster analysis technique, in which leather and hide defects were depicted as color-coded amplitude maps, or C-scans. Recently new research was carried out to study the effects of transducer frequency, thickness of leather, and AU gain on the resultant AU amplitude received, which was shown in a C-scan imagine. Observation showed that a lower frequency of 100 KHz yielded better transmission of AU waves through samples and the AU gain should be less than -5dB. In addition, the amplitude of the C-scan decreased with the thickness of the samples. This study has provided a significant guidance for successful AU testing.
 
 
Flocculation Behaviors of Collagen Protein-Al(III) Composite Flocculant 
by Ruiqin Li, Jianfei Zhou, Xuepin Liao, Wenhua Zhang and Bi Shi
Volume: 109      Number: 2     Page: 56-62     Year: 2014
Hydrolyzed collagen protein (HCP) was prepared by the hydrolysis of solid skin wastes, and then cross-linked with glycerol triglycidyl ether (GTE) to produce cross-linked collagen protein (CCP). By combination CCP with different amounts of Al2(SO4)3, a series of CCP-Al (III) composite flocculants (CCP-Al) were successfully synthesized. A kaolin suspension (5 g/L) was utilized as a model system to investigate the flocculation behaviors of the as-prepared flocculants. When the dosage of the CCP-Al was 50 mg/L, the flocculation extent reached 95% in 20 minutes with the sludge volume ratio lower than 15%. Under the same conditions, the CCP-Al exhibited better flocculation performance than the Al2(SO4)3. Scanning electron microscope (SEM) observations revealed that the size of flocs formed by CCP-Al was larger than that of Al2(SO4)3, suggesting a better aggregation of flocs.
 
 
Extraction of Keratin from Unhairing Wastes of Goatskin and Creating New Emulsion Formulation Containing Keratin and Calendula Flower (Calendula officinalis L.) 
by E. Bayramoglu, A. Yorgancioglu, G. Yeldiyar and E. Onem
Volume: 109      Number: 2     Page: 49-55     Year: 2014
This study demonstrates the use of keratin extracted from unhairing wastes of goatskin for cosmetics. Keratin has been purified from unhairing wastes of goatskin according to the oxidation method for producing emulsions. The experimental process to prepare the emulsions includes Oil/Water (O/W) emulsion method with keratin and Calendula officinalis flower extract (Calendula officinalis L.). Four emulsion creams with different ratios of keratin and calendula ingredients were formulated. Fourier transform infrared spectroscopy (FTIR) analysis of the keratin purified and pH, viscosity and average particle size analyses of the emulsions prepared have been carried out. The results of the study have shown that keratin obtained from unhairing wastes of leather industry could be smoothly used in producing emulsion formulations with calendula flower ingredient.