Leather and Footwear Journal

Volume 23, no 4

Contents
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3D PRINTING OF PADS ON LASTS UTILIZED IN THE PRODUCTION OF CUSTOM-MADE COMFORTABLE FOOTWEAR
- Pages 231-240
  Maryna LESHCHYSHYN^{1, *}, Borys ZLOTENKO², Oleg SYNYUK¹, Svetlana KULESHOVA¹, Volodymyr ONOFRIICHUK¹, Yuriy MYKHAILOVSKYI¹
  - ¹Khmelnytskyi National University, 11, Instytuts’ka str., Khmelnytskyi, 29016, Ukraine, marfiichuk@gmail.com
  - ²Kyiv National University of Technologies and Design, 2, Nemirovich-Danchenko str., Kyiv, 01011, Ukraine
  ABSTRACT. The study investigated the process of adjusting the shape of the footwear last using solid modeling elements (individual pads) manufactured through 3D printing. Based on a comparative analysis of the results of anthropometric foot studies with the parameters of existing footwear lasts available on the Ukrainian market, the rationale for improving the method of correction lasts using individual pads in mismatched anthropometric zones to achieve consumer foot comfort is substantiated. A schematic diagram of the transverse cross-section of the foot-lasts-pads-footwear system is provided. The study obtained dependencies of the calculated radius of the outer contour of the pad on the thickness of the upper material of the footwear. The anthropometric regions of the foot that most commonly require adjustment in existing lasts to achieve the production of custom-made comfortable footwear have been identified. The method of adjusting the shape of the last has been improved based on the individual parameters of the customer’s foot, using pads manufactured using 3D printing technology. The interdependencies between stress and deformation under tension have been established, and the strength limit of polymer material samples for corrective pads obtained through 3D printing has been determined. The rational technological parameters of the 3D printing process using elastane material for corrective pads on lasts have been determined and implemented in the production of custom-made footwear.
  
  KEY WORDS: shoes, materials, modulus of elasticity, shoe last, 3D printing
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STUDY ON THE INFLUENCE OF BIOMECHANICAL CHARACTERISTICS OF FUNCTIONAL INSOLES ON THE FOOT OF ATHLETES DURING RUNNING
- Pages 241-246
  Guanghua ZHI*^*
  - Basic Teaching Department, Guilin University of Electronic Technology, Beihai 536000, China, dizhi1602@163.com
  ABSTRACT. Functional insoles can reduce foot injuries caused by running. In this paper, ten male volunteers from the Track and Field Department of Guilin University of Electronic Technology were selected as subjects to test the biomechanical characteristics of the foot, such as plantar pressure, impulse, and center line pressure distribution, when using normal insoles and shock-absorbing functional insoles made of latex, ethyl vinyl acetate (EVA), and conventional insoles. The results showed that the plantar pressure and impulse were mainly concentrated on the first toe, the middle of the metatarsal, and the lateral part of the heel. After using the shock-absorbing insoles, the average pressure and impulse of the first toe, second to fifth toe, lateral metatarsal, and lateral heel were significantly reduced, while the average pressure intensity and impulse of the medial metatarsal, middle metatarsal, and medial heel were significantly increased; the center line of pressure became longer and straighter, indicating that the running stability was improved.
  
  KEY WORDS: insole, shock absorption, foot, biomechanics
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DETERMINATION OF THE IMMERSION RESISTANCE OF POLYMERIC BIOCOMPOSITES BASED ON TPU (THERMOPLASTIC POLYURETHANE) / RECYCLED TPU / PROTEIN AND ELASTOMERIC WASTE MIXTURE
- Pages 247-256
  Mihaela NIŢUICĂ*, Maria Daniela STELESCU, Maria SÖNMEZ, Mihai GEORGESCU, Laurenția ALEXANDRESCU, Dana Florentina GURĂU, Mirela PANTAZI-BĂJENARU, Traian FOIAȘI
  - INCDTP – Division: Leather and Footwear Research Institute, 93 Ion Minulescu St., sector 3, Bucharest, mihaelavilsan@yahoo.com
  ABSTRACT. Collection and recycling of waste from the footwear industry (elastomeric waste) and leather goods (protein waste), as well as other related fields, in order to use it to obtain new products, also easy to recycle and environmentally friendly, is increasingly emphasized. Both elastomeric and protein waste mixed with current elastomers, thanks to new technologies, lead to obtaining new polymer structures / composites (biocomposites) with high-performance properties. This article describes the obtaining of polymeric biocomposites based on thermoplastic polyurethane/recycled thermoplastic polyurethane/mixed protein and elastomeric waste, and also the determination of their immersion resistance in different immersion environments. Recycled thermoplastic polyurethane waste, but also mixed protein and elastomeric waste (SBR rubber) were modified in the first phase by cryogenic grinding. Subsequently only the mixed leather and SBR rubber waste was modified with 5% polydimethylsiloxane (PDMS). The polymer biocomposite specimens were characterized from the point of view of immersion in liquids in various immersion environments, after being conditioned at room temperature for 22-24 hours. The characterization is done according to the ISO 1817:2015 standard, following the variation in volume (ΔV) and mass (ΔM). The immersion was carried out in brown and tightly closed containers. The immersion time was 22 hours, at ambient temperature.
  
  KEY WORDS: resistance to immersion, polymeric biocomposites, TPU, protein and elastomeric waste, recycled TPU
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OBTAINING NEW BIOEMULSIONS BASED ON LAVENDER EXTRACT AND SURFACTANTS
- Pages 257-266
  Demetra SIMION^{1, *}, Carmen GAIDĂU¹, Gabriela PĂUN², Daniela BERECHET¹, Roxana CONSTANTINESCU¹
  - ¹National Research and Development Institute for Textiles and Leather (INCDTP) – Division: Leather and Footwear Research Institute (ICPI), 93 Ion Minulescu st., 031215, Bucharest, Romania
  - ²National Institute for Research-Development of Biological Sciences, 060031 Bucharest, Romania
  ABSTRACT. New bioemulsions were created using biotechnologies based on lavender extract (oil) and two surfactants: Tween® 20 and Tween® 80 mixture: E1 – lavender oil/Tween® 20/water; E2 – lavender oil/ Tween® 80/water; E3 – lavender oil/ Tween® 20 and Tween® 80 (ratio 1:1)/water, for different concentrations (28.56%, 7.14%) of lavender oil, in order to improve surface properties with applications in leather industry. More concentrated emulsions with oil lavender (28.56%) were marked E1c, E2c, E3c. In the process of finishing the leathers by spraying with six types of emulsions obtained compared to an untreated leather, the aim was to improve the antifungal, antimicrobial properties as well as the softness, appearance of the leathers. The order of introducing components in the developed biotechnologies, the working conditions, and especially the choice of the concentration of surfactants >CMC, are essential in the solubilization of vegetable oils and obtaining the desired bioemulsions. Comparatively, bioemulsions were made for the version with two surfactants, but instead of lavender, immortelle was introduced, resulting in emulsions: Lemulsion, Iemulsion. The bioemulsions and leathers processed with them were analyzed by FTIR-ATR spectroscopy, DLS and microbiological tests. It can be seen that the leather with the largest amount of lavender after processing with concentrated emulsions is E3c (having the highest intensity over the entire spectral range) and the maximum absorption specific to lavender oil was found. The lavender oil is fixed better on the leathers than the immortelle oil, with the new bioemulsions created.
  
  KEY WORDS: new bioemulsions, biotechnologies based on lavender extract and surfactants, immortelle, leathers processed
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A REVIEW OF POTENTIAL ENZYMES: PROTEASE AND KERATINASE FOR DEHAIRING PROCESS AS CLEANER AND ECO-FRIENDLY LEATHER PROCESSING
- Pages 267-278
  Naimah PUTRI^{1, *}, Eka Legya FRANNITA²
  - ¹Department of Leather Processing Technolgy, Politeknik ATK Yogyakarta, Special District of Yogyakarta, 55281, Indonesia, naimah@atk.ac.id
  - ²Department of Leather Products Technolgy, Politeknik ATK Yogyakarta, Special District of Yogyakarta, 55281, Indonesia, eka.legya@atk.ac.id
  ABSTRACT. In recent decades, there has been growing concern and negativity from the environmental impact of industrial development, which produces lots of technological changes. The significant contribution of the leather industry has a good impact on the economic sector; however, it is faced with challenges caused by pollution to the environment. Special attention is required for disposal of solid wastes because of the large amounts that are generated and legal restrictions. Environmental problems are caused by the large amount of wastes originating from chemicals during processing, especially in dehairing process. Conventional dehairing by lime sulfide process causes high chemical oxygen demand emission, biological oxygen demand, and total suspended solids. The dehairing mechanism is vaguely understood at present from the point of view of the enzyme specificity, which is needed for consistent and satisfactory hair removal without deleterious effect on the leather quality. It is known that the use of enzymes has potential as an alternative that can be used to reduce the harm caused by toxic chemicals including for waste management. Recently, there has been increasing research on application of enzymes in various leather production processes. The use of protease and keratinase enzymes in leather processing industry has the most promising potential to improve the surrounding environment. Therefore, this study aimed to review relevant literature in terms of dehairing processes without adverse effects in order to make good quality leather. Further scientific discussion is needed for understanding the gap of these critical issues in this area.
  
  KEY WORDS: dehairing, protease, keratinase, eco-friendly, leather processing
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EUREKA PROJECT BIO-PLANT-PROTECT AS MODEL KNOWLEDGE TRANSFER BETWEEN ACADEMIC, RESEARCH AND INDUSTRY
- Pages 279-286
  Mihaela-Doina NICULESCU^{1, *}, Brîndușa Georgiana DUMITRIU², Stelica CRISTEA³, Lucreția MIU¹, Magdalena LASOŃ-RYDEL⁴, Joanna SOBCZYK⁵, Cosmin Andrei ALEXE¹
  - ¹INCDTP – Leather and Footwear Research Institute Division, Bucharest, Romania, mihaelaniculescu59@yahoo.com
  - ²SC BIOTEHNOS SA, Bucharest, Romania
  - ³University of Agronomic Science and Veterinary Medicine, Bucharest, Romania
  - ⁴Łukasiewicz Research Network - Institute of Leather Industry, Łódź, Poland
  - ⁵Pestila II Sp.zo.o.Sp.k., Wolborz, Poland
  ABSTRACT. This paper presents an example of interdisciplinary cooperation between scientific research, education and industry to develop innovative products. Through its complex, inter-related activities, the project generates innovation in bioeconomy, in the agrifood system, developing a double action product (protection for plants and stimulation of agricultural production), as well as treatment schemes adapted to pest control and amplification of germination, specifically designed for their applicability domain (e.g. apple orchards, tomato seeds).
  
  KEY WORDS: knowledge transfer, bio-fungicide, protection, nutrition, bioeconomy
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BIODEGRADABLE RETANNING MATERIAL FROM TANNERY TRIMMING WASTE: EXTRACTION, PREPARATION AND APPLICATION
- Pages 287-302
  Md. Farhad ALI^{1, *}, Papia HAUQUE², Md. ABDULLA-AL-MAMUN¹, Tamanna JAMAN¹
  - ¹Institute of Leather Engineering and Technology, University of Dhaka, Bangladesh
  - ²Dept. of Applied Chemistry and Chemical Engineering, University of Dhaka, Bangladesh
  ABSTRACT. The leather industry has long grappled with environmental challenges associated with waste disposal. One ton of wet-salted hides or skins generates approximately 650 kg of solid waste. The majority of trims and hair waste remain underutilized, with hair often discarded or used inefficiently. We initiated the creation of a retanning agent devoid of formaldehyde by utilizing discarded tannery trimmings, with the goal of promoting a circular economy approach in the leather processing industry in our sustainability efforts. Optimal hydrolysis conditions were determined, involving an alkaline (3.75% w/w NaOH) pre-treatment followed by thermal hydrolysis at 100 °C for 5 hours, effectively maximizing the use of trimmings. Similar treatments were applied to hair waste, particularly red sheep hair, yielding successful hydrolysis. Keratin hydrolysate-g-methacrylic acid (KH-g-MA) copolymers were synthesized through in situ polymerization, employing hydrolysates in a redox system. Characterization was carried out using dynamic light scattering and Fourier transform infrared spectroscopy. These newly developed copolymers were applied as retanning agents in the leather industry, enhancing leather qualities such as fullness, grain tightness, and color brightness. Moreover, they improved leather mechanical strength and reduced the need for post-tanning chemicals. This innovative approach not only addresses solid waste issues but also contributes to greener leather processing, thereby fostering a more sustainable environmental landscape.
  
  KEY WORDS: retanning material, trimming waste, retanning application
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INNOVATIVE TECHNOLOGIES FOR OBTAINING STRUCTURED EMULSIONS, BASED ON SEA BUCKTHORN EXTRACT AND TENSIDES
- Pages 303-310
  Demetra SIMION^{1, *}, Carmen GAIDĂU¹, Gabriela PĂUN², Daniela BERECHET¹, Roxana CONSTANTINESCU¹
  - ¹National Research and Development Institute for Textiles and Leather (INCDTP) – Division: Leather and Footwear Research Institute (ICPI), 93 Ion Minulescu st., 031215, Bucharest, Romania
  - ²National Institute for Research-Development of Biological Sciences, 060031 Bucharest, Romania
  ABSTRACT. New structured emulsions were obtained by innovative technologies based on sea buckthorn extract (oil) and two surfactants, sodium dodecyl sulfate and Tween® 80 mixture: Es – sea buckthorn oil/sodium dodecyl sulfate/water; Et – sea buckthorn oil/Tween® 80/water; Est – sea buckthorn oil/sodium dodecyl sulfate and Tween® 80 (ratio 1:1)/water, for different concentrations of sea buckthorn extract oil, in order to improve surface properties with applications in leather industry. Sea buckthorn extract (oil) has a strong antimicrobial and antifungal effect due to its content in: vitamins C and E, phytosterols, fatty acids, antioxidants and amino acids. The order of introduction of the components in innovative technologies, the working conditions and especially the choice of the concentration of surfactants >CMC, are essential in the solubilization of sea buckthorn oil and in obtaining the structured emulsions. The emulsions were characterized by optical microscopy with sea buckthorn oil at 23-50°C. The changes in the aggregation process were observed for each type of emulsion, the influence of temperature and the solubilization of sea buckthorn oil. Dynamic light scattering (DLS) for the emulsions showed the stability, concentration, particle size, polydispersity, zeta potential. The antimicrobial properties were analyzed by microbiological tests. FTIR measurements highlighted the interaction mechanism of surfactants with sea buckthorn oil from the structured emulsions. The leather samples were microbiologically tested, and antimicrobial and antifungal effects were observed. The new structured emulsions are original due to the successful inclusion of sea buckthorn extract (oil) with high potential for improved surface properties with applications in the leather industry.
  
  KEY WORDS: new structured emulsions, innovative technologies based on sea buckthorn extract and tensides, leathers processed
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