Leather and Footwear Journal

Volume 19, no 1

Contents
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Effects of the stride length on the gait and intra-limbs coordination of healthy children aged 3 to 6
- Pages 3-10
  Yuguo FENG¹, Bo XU², Jin ZHOU²*
  - ¹College of Applied Technology of Xihua University, No. 999 Jinzhou Road, Jinniu District, Chengdu City, 17345831@qq.com
  - ²National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, No. 24, South Section of First Ring Road, Wuhou District, Chengdu, zj_scu@scu.edu.cn
  ABSTRACT. Body motion adjusts while the stride lengths changes, but few studies report those influences on the gait mechanism and intra-limbs coordination of children; therefore, the purpose of our study was to evaluate the gait mechanism and intra-limbs coordination of healthy children aged 3-6 under stride length adjusting, so as to add the knowledge of motor development of healthy children. Forty-five healthy children and ten adults walked on a 6m walkway at three stride lengths (short stride (SS), normal stride (NS) and long stride (LS)) and key kinematical parameters such as Euler angles and angular velocities were first recorded by CodaMotion 3D measure system; and then those two variables were applied to calculate the continuous relative phase (CPR) which specified coordination in the knee and ankle. Results showed that when transferring from short stride to normal stride long stride, children were to deal with by increasing stride length, Froude number, swing phase, and decreasing frequency. However, there were no significant differences between SS and LS in kinematical parameters; meanwhile, those significant variations were not found between age groups. In terms of intra-limb's coordination, there were no significant differences in values of relative phases within and between age groups. In conclusion, as early as age 3, young toddlers have already mastered the basic ability in adjusting gait while walking.
  
  KEY WORDS: child development, gait, intra-limbs coordination, long stride, short stride
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Investigation and evaluation of the quality features related to comfort of casual shoes in Bangladeshi leading retail brands using physical and chemical standard test methods
- Pages 11-20
  Md. Rayhan SARKER, Amal Kanti DEB*, Manjushree CHOWDHURY*, Md. Israil HOSSAIN
  - Institute of Leather Engineering and Technology, University of Dhaka, Dhaka-1209, Bangladesh, md.sarkerdu.rayhan@gmail.com, debak.ilet@du.ac.bd, manjushreechow@gmail.com, israil.rafi@yahoo.com
  ABSTRACT. Several materials and chemicals are being used during manufacturing processes of shoes which are responsible for a good quality product. Nowadays it has been coming out of the current market of Bangladesh that leading retail brands are not providing good quality footwear to their customers. The aim of the study was to investigate different physical and chemical properties of sample shoe materials related to comfort features. Ten pairs of casual leather shoes were brought from five leading Bangladeshi retail brand outlets focusing on equal price point and best-selling article. These samples underwent different physical and chemical tests following standard methods of SATRA (Shoe and Allied Trade Research Association), IUP (International Union for Physical testing) and SLC (Society of Leather Chemists) such as whole shoe flexing, sole adhesion, flexing endurance of upper materials, SATRA-Bata sole flexing, shrinkage temperature, percentage of chromium (expressed as % Cr2O3) content, water absorbency, water vapor permeability (W.V.P) and pH. All samples showed poor sole adhesion as average separation load were recorded 13.9 kg, 14.2 kg and 20.1 kg at the toe, ball and heel areas respectively that were far below than standard values. Three sample soles were broken down after 30,000 and 40,000 cycles rendering poor flexing resistance, whereas the upper materials of four samples showed poor flexing endurance with break pipiness scale ratings 4/5 and 4 before desired 50,000 cycles. Especially sole adhesion and flexing endurance properties should be ameliorated to gratify customers' expectations.
  
  KEY WORDS: casual shoe, comfort, chemical test, physical test, quality
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Motion compensation strategy of preschoolers coping with tasks of stride length changes and curve turnings: in terms of centre of mass
- Pages 21-28
  Mingyu HU¹, Quting HUANG¹, Bo XU¹, Wuyong CHEN¹, Jianxin WU², Jin ZHOU^1,2*
  - ¹National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University; Chengdu 610065, P. R. China
  - ²Science Lab, Zhejiang red dragonfly footwear Co., LTD., Zhejiang Province, Wenzhou 325100, P. R. China
  ABSTRACT. The purpose of this study was first to disclose motion compensation strategy of healthy preschoolers according to evaluate how the stride length changes and curve turnings affected their Centre of Mass (CoM) performances; and then to comprehend the process of children develop in motion. Ten healthy children aged around 6 and 9 adults aged 23-47 were recruited in this study. The CoM was calculated based on four key markers in pelvis and its trajectory in five tasks including the stride length changes (short stride, straight walking and long stride) and curve turnings (0°-30°-60°) were first recorded; and then variables such as trajectory of CoM in sagittal and coronal plane, Unit of Energy (uEN), Energy Kinetic (uEk) and Gravitational Potential Energy (uEg) in the critical gait period were analyzed. Results show that as the stride length increase, child accordingly enlarged their motion range of CoM both in mediolateral and vertical direction to assist the wholebody movement; meanwhile, children's uEN increased as the stride length prolonged. Further, since 10%GC, child's CoM shifted gradually to the curving direction (right) as curve turning angle aggregated; while, dramatic change occurred at 60%GC, where a larger CoM deviation was found in 60° than that of 30°. The uEN of children was low before 60%GC, but it raised prominently after 60%GC. Overall, adult-like CoM were partly found in healthy preschoolers when coping with varied gait tasks, however distinctions existed which demonstrated that compensative strategies of those children were still developing.
  
  KEY WORDS: center of mass, children development, compensative strategy, stride length, curve turning
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Influence of adding functionalized microparticles on the physicalmechanical, structural, and processability properties of thermoplastic rubber
- Pages 29-40
  Maria SONMEZ¹*, Laurentia ALEXANDRESCU¹, Mihai GEORGESCU¹, Dana GURAU¹, Ciprian CHELARU¹, Mircea JUGANARU², Anton FICAI³, Roxana TRUSCA³
  - ¹INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu, 031215 Bucharest, Romania, maria.sonmez@icpi.ro
  - ²PROTECT STYL INDUSTRY S.R.L., 30 Bulevardul Unirii, 600192, Bacau, Romania
  - ³POLITEHNICA University of Bucharest, Faculty of Applied Chemistry and Material Science, 1-7 Polizu St., Bucharest, Romania
  ABSTRACT. The aim of this paper was to assess the influence of powders, modified on the surface with organic-inorganic compounds, on the block copolymer styrene-butadiene-styrene (SBS) type thermoplastic rubber properties, obtained by the mixing. Powder surface of kaolin, CaCO₃, and MgCO₃ modification with precursors of TiO₂ and SiO₂ aimed at improving the interface, dispersion, and physico-mechanical properties, of the composites based on SBS. Titanium isopropoxide was used as a precursor to TiO₂, and for SiO₂ the tetraethyl orthosilicate (TEOS). Modified powders were morpho-structural characterized by SEM, FTIR, and EDAX. FTIR spectra highlight the bands characteristic of individual powders, but functional groups derived from TiO₂ and SiO₂ could not be viewed. Due to this issue, it has resorted to an EDAX analysis of all the powders, and the presence of silicon and/or titan elements confirmed that modification occurred. SEM microscopy performed on modified versus the simple powder, shows a reduction of areas containing particle agglomerations, due to the reduction of surface energy and implicitly electrostatic, and attraction forces. The results of the physical-mechanical properties, show that for the composites containing mixture of modified particles (even at high amounts 75%) values of resistance to tear strength, elongation at break, elasticity, were superior to blends containing unmodified particles, to SBS respectively. The results obtained confirm that by modifying the particle surface, improves dispersion, and compatibility between phases, due to achieving optimal interface between particle/polymeric matrix. Melt flow index are lower for the reinforced SBS with high amounts of particles, but without raising issues of processability.
  
  KEY WORDS: styrene-butadiene-styrene, carbonates, aluminum silicate, organic-inorganic compounds, characterization
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Sustainability in the Portuguese fashion accessory & footwear industry (case studies)
- Pages 41-50
  Patricia AZAMBUJA, Antonio MARQUES*, Ana BROEGA
  - University of Minho, Campus de Azurem - 4600-065 Guimaraes, Portugal, pati_azambuja@hotmail.com, adinis@det.uminho.pt, cbroega@det.uminho.pt
  ABSTRACT. The Portuguese footwear has the second most expensive pair of shoes produced in Europe (Italy has the most expensive), it is the only country in the world that produces more footwear than it consumes. The main environmental impacts caused by this sector are at residues containing chromium in its composition, such as leather flaps and leather powder, which are difficult materials to degrade by the environment and therefore highly polluting. Being a thriving industry is also one of the firsts to have concerns with the issue of sustainability, emerging already some cases of good practice in the framework of sustainable strategies. This paper uses the case study research strategy of footwear brands and Portuguese accessories. The field study shows that the most commonly adopted sustainability principles are the choice of less polluting materials, less aggressive tanning leather, or even alternative materials. Products created with greater cultural value and in a more traditional way, towards the adoption of a slow fashion in the footwear sector.
  
  KEY WORDS: Sustainability, fashion footwear, upcycling
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Simulating the surface of litchi grain leather by creating quadrilateral-continuous pattern in Adobe Illustrator CC
- Pages 51-60
  Wei WANG^{1, 3}, Weijie WANG³, Biyu PENG^{1, 2}, Luming YANG^{1, 2}*
  - ¹Sichuan University, National Engineering Laboratory for Clean Technology of Leather Manufacture, South Section 1, Yihuan Road, No.24, 610065, Chengdu, China
  - ²Sichuan University, Key Laboratory of Leather Chemistry and Engineering, 610065, Chengdu, China
  - ³Sichuan University, Faculty of Textile and Garment Engineering, 610065, Chengdu, China
  ABSTRACT. The paper illustrates an approach of creating quadrilateral-continuous pattern for simulating litchi grain leather surface in order to solve the issue that the designer of leather products cannot simulate litchi grain surface simply or realistically. Adobe Illustrator CC is a kind of design software that possesses pattern-editing mode. Based on both the image of the litchi grain leather sample scanned by stereo microscope and the rationale behind the quadrilateral-continuous pattern, we obtained the wrinkles and pores of litchi grain leather sample in Adobe Illustrator CC without using any sophisticated algorithm, which in turn resulted in realistic and various effects on the surface of litchi grain leather. Moreover, the pattern exported from Adobe Illustrator CC can also be widely used in other kinds of design software.
  
  KEY WORDS: litchi grain leather, quadrilateral-continuous pattern, Adobe Illustrator CC, surface simulation
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The development of shoe design and footwear sector in Bulgarian geography from the pre-milestone periods to the present
- Pages 61-66
  Sevim YILMAZ*
  - Pamukkale University, Denizli Technical Vocational School of Higher Education, Denizli, Turkey, e-mail: sevimy@pau.edu.tr
  ABSTRACT. The footwear has an important role in human life from the past to the present due to its ability to protect the human foot and provide comfortable walking. In time, different nations have created their own national shoes, and these national shoes have varied and changed in accordance with the relevant climate and geographic conditions. In the Bulgarian people, the production of its own shoes has gained momentum since the 17th century. Footwear industry in Bulgaria was been formed as sector and good developed due to time of national government from 1947-1980 years. Then after the revolution in 1990 year the factories were privatized. The aim of this study is to investigate the structure of shoes designed in Bulgarian geography in terms of aesthetics and comfort in the historical process and the status of the shoe industry since 2000s to the present.
  
  KEY WORDS: footwear design, Bulgarian footwear industry
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Technology of reducing Cr(VI) on leather processing using mimosa as retanning agent
- Pages 67-72
  Emiliana ANGGRIYANI¹*, Alfani Risman NUGROHO², Nur Mutia ROSIATI¹
  - ¹Department of Leather Processing Technology, Politeknik ATK Yogyakarta, Sewon, Bantul, 55281, Yogyakarta, Indonesia, emiliana.anggry@gmail.com
  - ²Department of Furniture Production Engineering, Politeknik Industri Furnitur dan Pengolahan Kayu, Kendal, Jawa Tengah, Indonesia
  ABSTRACT. Hexavalent chromium or Cr(VI) is toxic. Therefore, it is necessary to prevent or minimize its existence. This study aims to explain the effect of using mimosa as a retanning agent on the reduction of Cr(VI) content in goat crust skin. The post-tanning process was done by the process of 1st retanning, neutralization, fatliquoring, 2nd retanning and fixing. The retanning process 2 was performed with three treatments, 0% of mimosa, 3% of mimosa and 6% of mimosa. All the data were analyzed by the One Way ANOVA then followed by the Duncan Multiple Range Test. The results obtained were the decrease of hexavalent chromium content with the addition of mimosa during the retanning process. The use of 3% of mimosa is more effective to reduce the formation of Cr(VI) than 6% of mimosa. It can be said that the use of mimosa as a retanning agent can reduce the formation of Cr(VI).
  
  KEY WORDS: Cr(VI), leather processing, mimosa, retanning agent
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