Leather and Footwear Journal

Volume 18, no 2

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Research on recycling of waste leather produced in leather manufacturing process based on supply chain management
- Pages 75-82
  Shouhui HE¹*, Yan WANG², Xiaodong LI¹, Hongda LIU³
  - ¹Linyi University, Linyi 276000, China
  - ²Linyi Branch Transportation Planning and Design Limited Company, Linyi 276000, China
  - ³Stated-Owned Assets and Administration Commission of Linyi, Linyi 276000, China
  ABSTRACT. Leather industry is a consumer-goods sector closely linked with national economic development. With the slowdown of China's economic growth, the leather industry has entered a new normal of steady development under immense pressure. On the upside, the industry can enrich the material life of consumers. On the downside, leather production unleashes a series of threats to the environment. For example, it is urgent to recycle the gigantic amount of waste leather in such an environmentally conscious era. Therefore, this paper presents a model for the manufacturer who produces lots of waste leather in manufacturing, builds another model for the recycler who recovers the waste leather produced by the manufacturer, and combines the two models into an integrated model for recycling of waste leather produced in leather manufacturing process. Then, the model was applied to a numerical analysis.
  
  KEY WORDS: waste leather, leather manufacturing process, supply chain management
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Competence of coordination in lower limbs of children aged 3-6: clues from their backward walking
- Pages 83-92
  Jin ZHOU^1,2, Haozhen WU¹, Mingyu HU¹, Wuyong CHEN¹, Jianxin WU², Bo XU¹*
  - 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. Since current literature does not explain how children aged 3-6 reacted when the walking direction was reversed or what its mechanism is, the aim of this study was to understand the mechanism of their 'Neuro-musculo-skeletal' systems in the process of direction changes, as well as its coordination features. The kinematics of forward walking (FW) and backward walking (BW) of 96 subjects were measured by the Coda motion system and their Euler angles in lower limb joints were first collected. According to the coordination algorithm, the phase angle (PA) in the knee and ankle and the continuous relative phase angle (CRP) between the two joints were calculated; further the mean, standard deviation (SD) and range of data for variables of PA and CRP were contrasted between FW and BW. All the statistical models were executed under SPSS with a significance level of 0.05 and a confidence interval of 95%. The results show that children in BW first had an unstable velocity in their ankles; further, PA in both their ankles and knees were distributed in a limited range. Meanwhile the key gait events were not obtained in BW in all age groups. A similar CRP was seen between FW and BW, but a significant difference existed between the two types of gait. The majority of the mean and range of PA and CRP were recorded with significant distinctions between FW and BW in each age group. Finally, significant gender differences existed in all variables of BW in each age group. Overall, although achieving the BW was easy for preschool toddlers (aged 3-6), but their coordination in lower-limb were still in developing and further fine tuning; moreover, their clues in backwarding also tell the detail of development in the 'Neuro-musculo-skeletal' system.
  
  KEY WORDS: backward walking, lower limb coordination, continuous relative phase, phase angle, healthy children
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Characteristics of teenagers' gait and foot pressure distribution in mid-long distance running
- Pages 93-100
  Yimeng FAN¹, Caixia FU², Lili ZHAO¹*, Lijing FAN³, Qidong HUANG⁴
  - ¹Department of Sports Work, Hebei Agricultural University, Baoding 071000, China
  - ²Department of State Assets Management, Hebei Agricultural University, Baoding 071000, China
  - ³Department of Mechanical and Electrical Engineering, Hebei Agricultural University, Baoding 071000, China
  - ⁴Suihua University, Suihua 152061, China
  ABSTRACT. By using Rs-scan insole pressure test system, this article measures and analyses teenagers' gait and foot pressure in mid-long distance running and conducts quantitative experiment to mid-long distance running by selecting master, level 1&2 teenage runners to form the experiment group and ordinary university students to form the control group. Firstly, it briefly introduces the development of research on running gait biology and foot pressure test system. By dividing feet pressure into various areas and using effective experimental method, it designs and measures such parameters as gait cycle & phase, Center of Pressure (COP) track, Pressure-Time Integral (PTI), Partition Peak Pressure (PP), etc. Finally, it reaches relevant conclusions through comparative analysis of measurement data. This research provides theoretic support and data basis for research on foot pressure distribution, mechanism of force in different phases of sport and prevention of sports injury.
  
  KEY WORDS: mid-long distance running, rs-scan, gait, foot pressure distribution characteristics, contrast experiment
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The influence of sodium chloride replacement with potassium chloride as a curing agent on the quality of tanned pufferfish (Arothon reticularis) skin
- Pages 101-108
  Raden Lukas Martindro Satrio Ari WIBOWO*, Emiliana ANGGRIYANI, Ragil YULIATMO
  - Department of Leather Processing Technology, Politeknik ATK Yogyakarta, Sewon, Bantul, 55281 Yogyakarta, Indonesia
  ABSTRACT. The pufferfish skin is a by-product that is underutilized. Skin tanning is the prospect way to enhance the economic value of pufferfish skin. The tanning process is a long one, including the process of curing the skin. Sodium chloride is commonly used for curing the skin. However, sodium chloride can increase the total dissolved solids (TDS) that will be problematic in the environment. Potassium chloride can be used instead of sodium chloride. This study aims to determine the influence of substituting sodium chloride with potassium chloride on the quality of tanned pufferfish skin. Sodium chloride and potassium chloride were used in the skin curing process, while the storage time was 0, 1, 2, and 3 weeks. The assays performed are salt concentration on the skin, scanning electron microscope (SEM), FTIR, and physical quality of tanned pufferfish skin. The results showed that the salt content of potassium chloride in the skin was more easily absorbed than the salt of sodium chloride. The SEM and FTIR tests, descriptively, show no significant difference. The physical quality of the pufferfish skin preserved using potassium chloride is better than that of sodium chloride. Potassium chloride deserves to be used as a substitute for sodium chloride.
  
  KEY WORDS: pufferfish, skin curing, salt, sodium chloride, potassium chloride
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Impact of sport dancing on the dynamics characteristic of foot movement of college students
- Pages 109-116
  Yi LIU*
  - College of Physical Education, Hubei University, Wuhan 430062, China
  ABSTRACT. With the merits of improving physical quality, body shaping and physical aesthetics, sport dancing is more and more popular among college students. The gestural movement of sport dancing is mainly realized through the reaction of feet after contacting the ground, so it is necessary to scientifically analyze the influence of sport dancing on the dynamics characteristic of foot movement of college students. In this paper, the effect of sport dancing on the insole pressure intensity and gait characteristics of college students is studied by means of experimental test. First, relevant concepts were elaborated. In the experimental test, the foot pressure test system was adopted. And then analysis was made after the comparison between the experimental group and the control group. Finally, analysis and discussion of the experimental results were carried out. This paper is of great significance for evaluating the impact of sport dancing on the healthy development of college students' feet and guiding the force condition of the feet in sport dancing.
  
  KEY WORDS: sport dancing, foot pressure test system, gait, insole pressure intensity, experimental test
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Optimization of bovine leather soaking process
- Pages 117-122
  Angela QUEIROS, Vania F.M. SILVA*, Telma SANTOS, Antonio CRISPIM
  - CIETI/ISEP - Centre of Innovation on Engineering and Industrial Technology/IPP School of Engineering, Rua Dr. Antonio Bernardino de Almeida, 831, 4200-072 Porto, Portugal
  ABSTRACT. High quantities of water, chemical reagents and time are needed in leather processes which result in a huge investment for the tanning industry, therefore it is necessary to optimize it. Soaking is the first stage of leather process, responsible for cleaning and re-hydrating the skin through an aqueous bath. In this work, to study an ecological approach of the soaking step, two different types of soaking were evaluated comparing the traditional method against an enzymatic method. Bactericide, a wetting agent, a degreaser and enzymes were applied on the skins with two ways of preservation, salted skin and green skin. The pH value, conductivity and hide weight were determined to evaluate the process. The enzymatic method showed a better soaking performance giving good indications for an ecological approach of the soaking process.
  
  KEY WORDS: green skin, leather process, salted skin, soaking
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Influence of the increasing weight of the backpack on the balance of movement to primary school students
- Pages 123-130
  Nan ZHOU^1,2, Wuyong CHEN¹*, Jin ZHOU¹, Luming YANG¹
  - ¹National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu, 610065, China
  - ²Guangzhou Shiling Leather & Leather Products Investigation Center, No.6 Yangguang Road Shiling Town, Huadu district, Guangzhou city, Guangdong province, 510850, China
  ABSTRACT. Nowadays, the backpack is becoming more and more important in people's daily life in our society. It has aroused the concern of the community that primary school students carry heavy bags. Heavy loading may cause some problems, like spinal, shoulder and back pain, etc. Consequently, it will affect the growth and development of students directly or indirectly. Thereby, the aim of this paper was to understand the influence of increasing the weight of the backpack on the balance of movement, and to explore the effect of heavy loading on the growth and development of those subjects. 100 healthy primary school students (7-12 years old) were recruited and they were guided in walking with a backpack loading of 5%, 10%, 15%, 20% and 25% body weight. Their kinematic and kinetic data were measured by Footscan plantar pressure system and 3D motion capture. Parameters of center of pressure and vector angles within two lower limb joints were calculated to quantify the relationship between the loading and balance. Our results show that an increase of weight of the backpack has limited effect on the track of the center of pressure, and pupils can cope with the balance risk brought by the increase of load. In order to maintain balance control, students adjust their posture to eliminate the balance risk factors caused by loading. While increasing of loading had a great effect on body posture, 15% BW (Body Weight) loading could be considered to be a safe value.
  
  KEY WORDS: backpack load, center of pressure, vector angle, motion balance, primary school students
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Analysis of characteristics in China classic dancers' gait pattern
- Pages 131-138
  Yihong ZHAO^1,2, Ziyu LIU¹, Xuelian ZHANG³, Luming YANG^1,2*, Wuyong CHEN¹
  - ¹National Engineering Laboratory for Clean Technology of Leather Manufacture, Chengdu, 610065, China
  - ²Key Laboratory of Leather Chemistry and Engineering (Sichuan University), Chengdu, 610065, China
  - ³Sichuan Vocational College of Art, Chengdu 610065,China
  ABSTRACT. China Classic Dance is one of the most important and popular dancing in China and has become more and more popular from all over the world. However, the special gait patterns for the China Classic Dancers are not clear. The purpose of this study was to compare the characteristics of plantar pressure distribution in the China Classic Dancers and the non-dancers, and recognize if force transference happened. Gait data (PP, Fmax, PTI, FTI and FTIrel) from 93 China Classic Dancers and 30 non-dancers were analyzed. The plantar force transference was accessed with a load-transfer algorithm. Significant differences were found in plantar pressure distribution between the two groups: 1. maximum forces for China Classic Dancers significantly lower than the control group except the T1 and M2 regions; 2. peak pressures showed significant decrease in the China Classic Dancers except the M2 region; 3. the force-time integrals and pressure-time integrals in each region reduced significantly in comparison with the controls; 4. main significant load transferences were observed from T1, lateral forefoot (M3-5), midfoot and HM regions to the medial forefoot (M1-2) areas (T1, M3-5, MF, HM->M1-2). And the medial to lateral transferences were typical in toes and heel regions (T1->T2-5, HM->HL). These results suggested a typical gait patterns for the China Classic Dancers. Further investigation is needed in sports biomechanics and injuries for this special population.
  
  KEY WORDS: China Classic Dance, plantar pressure, load transference
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Feasibility of application of finite element method in shoe slip resistance test
- Pages 139-148
  Quting HUANG¹, Mingyu HU¹, Bo XU¹, 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. Finite element analysis (FEA) has been widely used in engineering and construction in simulating forces and interactions and its application in footwear have become quite ripe by being researched for over 30 years. The aim of this study was to investigate the slip resistance of the outsole to learn (1) the feasibility of FEA in the test of outsole slip resistance (2) frictional interactions between outsole and contact surface by experiment test and finite element analysis. A static friction tester was used for static slip resistance test and a SATRA STM 603 slip resistance tester was used for dynamic slip resistance test. Outcome showed that value of SCoF was a little bit higher than that of DCoF both in ET and FEA, and value of coefficients obtained in ET was higher. With the increase of COF value, the displacement of outsole decreased while stress of the outsole increased. In conclusion, FEA application is feasible in footwear resistance testing. Stability of the outsole with superior slip resistance is good in both longitudinal and transverse direction. During walking, it has a strong resistance to the slipping tendency to prevent tumble and sprain.
  
  KEY WORDS: Finite element model, Coefficient of friction, Slip resistance, Outsole
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Studies on waterproofing wet-white leather
- Pages 149-152
  Vania F.M. SILVA1*, Mayerlys MONCADA¹, Antonio CRISPIM¹, T. CRUZ², Filipe CRISPIM^2,3
  - ¹CIETI / ISEP - Centre of Innovation on Engineering and Industrial Technology / IPP School of Engineering, Rua Dr. Antonio Bernardino de Almeida, 831, 4200-072, Porto, Portugal
  - ²INDINOR - Industrias Quimicas, SA, Porto, Portugal
  - ³CTIC - Technological Centre for Leather Industry, Alcanena, Portugal
  ABSTRACT. Water resistance remains one of the more difficult goals to attain in leather manufacture. Although much is known from a scientific perspective, a problem persists when waterproofing wet-white leathers. The aim of this work was the study of the effect of different retanning agents on the waterproofing of wet-white leather produced by glutaraldehyde and syntan pre-tannage process. For that, a waterproofing process based in a waterproof fatliquor and a fluorocarbon based chemical, was tested applying different retanning resins, vegetable extracts and a dispersing agent to small leather pieces. Water resistance was evaluated by water absorption during 30 min in a static water bath at 25°C. It was shown that retanning agents reduce water resistance when compared with the standard process without them. The reduction effect is stronger when a normal retanning acrylic resin, natural chestnut extract, and a dispersing agent are used. The water resistance reduction effect of tara extract, mimosa extract, quebracho extract, melamine resin, dicyandiamide resin and styrene maleic resin is not so evident. This work needs to be continued in order to evaluate other retanning chemicals, pass to a larger scale and then evaluate the water resistance by the common methods of the tanning industry.
  
  KEY WORDS: leather, waterproof, wet-white
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Application of QFD method in fitness footwear production
- Pages 153-162
  Alina IOVAN-DRAGOMIR*, Alexandra LUCA
  - "Gheorghe Asachi" Technical University, Faculty of Textile - Leather and Industrial Management, 28 D. Mangeron, Iasi, Romania
  ABSTRACT. In order to obtain a better product it is important to integrate the consumer requests in all production levels, starting with research, design and till the end of production process. One of the most popular methods used to increase the quality of a product is Quality Function Deployment. The result of application of QFD method in footwear is presented in this paper. The consumer requests are expressed by completing a questionnaire. The group of respondents consists of men and women, between 20 and 50 years old, who practice fitness more than twice a week. Their opinions are inventoried, analysed and in the end, the most important ones are the input information for the quality house. The result of the study is a better product and for the producers a guideline to obtain a product according to consumer expectations.
  
  KEY WORDS: Quality Function Deployment, fitness footwear, quality house
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