Leather and Footwear Journal

Volume 12, no 3

Contents
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Comparing the Impact of Lipolytic Enzyme Preparations in Additional Soaking and Degreasing of Fleshed Pig and Sheep Skins
- Pages 175-182
  Vasil TSANOV*, Dimitrina IVANOVA, Margarita KOLEVA
  - University of Chemical Technology and Metallurgy, Department of Textile and Leather, 8 Kl. Ohridski bul., 1756 Sofia, Bulgaria, email: vasil.tsanoff@tsanoff-classic.com
  ABSTRACT. Appropriate use of enzyme preparations in pretanning enzymatic processes for treatment of pig and sheep skins with high content of natural fats needed comparative analysis of the mechanisms of their action of degreasing and the general rate of opening up of the fibrous structure of skin tissue. An aqueous degreasing process with enzyme addition is recommended.
  
  KEY WORDS: lipase, animal fats, fatty acids
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Scientific Investigation of Leather in Ethnographical Objects by Molecular Spectroscopy and MHT
- Pages 183-192
  Cristina CARSOTE¹*, Lucretia MIU², Irina PETROVICIU¹, Doina Maria CREANGA³, Maria GIURGINCA⁴, Wilfred VETTER⁵
  - ¹National Museum of Romanian History/Centre of Scientific Research and Investigation (MNIR/CCIS), Bucharest, Romania, email: cristina.carsote@mnir.ro
  - ²INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu, Bucharest, Romania, email: icpi@icpi.ro
  - ³Bucovina Museum (MB), Suceava, Romania
  - ⁴Politehnica University of Bucharest/Center for Environmental Protection and Ecologic Technologies (UPB/CPMTE), Bucharest, Romania
  - ⁵Institute of Science and Technology in Arts, Academy of Fine Arts, Vienna, Austria
  ABSTRACT. Collagen-based materials in museum objects may suffer physical-chemical and structural changes under the influence of environmental factors. This alteration can be evaluated and quantified at different levels using several analytical techniques, such as infrared spectroscopy (FTIR) and UV-VIS-NIR, thermal analysis (TG, DSC), shrinkage stability measurement of collagen fibers (MHT technique), electronic microscopy (SEM, TEM). This paper presents the scientific investigation of leather in ethnographical objects belonging to Bucovina Museum by using molecular spectroscopy (FTIR and UV-Vis-NIR) and MHT technique.
  
  KEY WORDS: ethnographical leather, level of degradation, FTIR and UV-Vis-NIR spectroscopy, MHT technique
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Rheological behaviour of some collagen extracts
- Pages 193-200
  Madalina Georgiana ALBU¹, Mihaela Violeta GHICA²*, Keyong TANG³, Jie LIU³, Gheorghe COARA¹
  - ¹INCDTP Division Leather and Footwear Research Institute, Collagen Department, 93 Ion Minulescu Str., 031215, Bucharest, Romania, e-mail: albu_mada@yahoo.com
  - ²Carol Davila University of Medicine and Pharmacy, Faculty of Pharmacy, Physical and Colloidal Chemistry Department, 6 Traian Vuia Str., 020956, Bucharest, Romania, email: mihaelaghica@yahoo.com
  - ³Zhengzhou University, College of Materials Science & Engineering, 450052, Zhengzhou, China, email: keyongtang@yahoo.com.cn
  ABSTRACT. Collagen extracts such as hydrogel, gelatin and hydrolysate were obtained from bovine hide. They were characterized by physical-chemical properties such as dry substance, total nitrogen, ash, fat, proteic substance (calculated from nitrogen content) and pH. Then, the analysed collagen extracts were adjusted at 1% collagen, pH 7.4 in order to be used as main components in drug delivery systems. The rheological properties of collagen hydrogel, gelatin and hydrolysate were determined and the following rheological models were established: Ostwald-de Waele for hydrolysate and gelatin and Herschel-Bulkley for hydrogel.
  
  KEY WORDS: collagen, hydrogel, gelatin, hydrolysate, rheology
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Study on the Influence of the Hardener over the Properties and Structure of Adhesives Based on Chloroprene Rubber
- Pages 201-214
  Darina ZHELEVA*
  - University of Chemical Technology and Metallurgy, Textile and Leather Department, 8 Kliment Ohridsky blvd., 1756 Sofia, Bulgaria, email: darinajeleva@abv.bg
  ABSTRACT. Polychloroprene solvent based contact adhesives are a substantial part in bonding the different substrates in the shoe, due to some peculiarities in the structure of chloroprene rubber. To increase the adhesion of the bonding of some materials, two-component polychloroprene adhesives are used. As a second component or hardener, polyisocyanate in solution is used. The aim of this study is to investigate the influence of the hardener (polyisocyanate) in the adhesive compositions based on chloroprene rubber on the properties and overmolecular structures during the formation of adhesive joint. It has been a comparison between the data from mechanical tests with data from microscopic studies of these adhesives to clarify the reasons for the formation of adhesive joint in the presence and absence of a hardener. Microscopic observations show that the crystalline texture of the adhesive composition improves in the presence of hardener. It also leads to increased cohesion forces within the adhesive film as it crosslinks the elastomeric macromolecules and creates a stronger bond between them, but in contrast, it weakens the adhesion forces between the adhesive and substrate. Mechanical tests confirm the conclusion of morphological studies on improving the cohesion and weakening the adhesion forces in the presence of hardener in the adhesive compositions.
  
  KEY WORDS: polychloroprene adhesive, hardener, morphological structure, adhesiveness
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Preparation and Characterization of Collagen:Amorphous Calcium Phosphate Composites
- Pages 215-222
  Maria Diana VRANCEANU¹*, Rami SABAN¹, Madalina Georgiana ALBU², Iulian ANTONIAC¹
  - ¹Politehnica University of Bucharest, 313 Independentei Street, 060042, Bucharest, Romania, email: vranceanudiana@gmail.com
  - ²INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu Street, 031215, Bucharest, Romania, email: madalinaalbu@gmail.com
  ABSTRACT. Collagen:amorphous calcium phosphate compositions were prepared by lyophylization and spongious composites for regeneration of bone defects were obtained. The spongious composites were characterized by Fourier transform infra-red (FT-IR) spectroscopy, scanning electron microscopy (SEM), water absorption and enzymatic degradation by collagenase. The results showed spongious composites with interconnected pores with embedded particles of mineral phase. Their biodegradation is less for the composite with 75% amorphous calcium phosphate (ACP3), as results of FT-IR and collagenase degradation showed. Due to their properties, the obtained composites could be potential biomaterials for bone tissue engineering.
  
  KEY WORDS: composite, collagen, amorphous calcium phosphates, enzymatic stability
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Modern Techniques for Concentration of Active Principles from Plant Extracts, Based on Membranary Technologies
- Pages 223-230
  Demetra SIMION¹*, Carmen GAIDAU¹, Gabriela PAUN², Margarita KOLEVA³, Snezjana CUPARA⁴
  - ¹INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu st., sector 3, postal code: 031215, Bucharest, Romania, email: demetra.simion@yahoo.com
  - ²INCDSB, Bucharest, Romania
  - ³University of Chemical Technology and Metallurgy, Textile and Leather Department, 8 Kliment Ohridski Blvd., Sofia, 1756, Bulgaria
  - ⁴Kragujevac Medicine Faculty, Serbia
  ABSTRACT. This work is focused on the separation and concentration of the active principles from the Viscum album and Tymus vulgaris aqueous extracts by using membrane techniques. By membranes processes such as microfiltration ultrafiltration both the proteins, polyphenols and flavonoids concentration and their separation from the compounds with smaller molecular weight (free amino acids, monosaccharides, etc.) that pass through the membranes were obtained. The main advantages of membranary technologies for separation and concentration of active principles from plant extracts are the following: low costs, high separation yield, high purity, absence of phase changes, process development at room temperature and preservation of active principles, simplicity, modulated compact installations.
  
  KEY WORDS: plant extracts, active principles, ultrafiltration, microfiltration, reverse osmosis
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