2024 Vol.34(3): 1–8    [Abstract] ( 3 )    [PDF 2084 KB ] ( 0 )

Cationic amphiphilic copolymer (PSD) was synthesized by free radical polymerization reaction and then was applied in the retanning of TWS organic tanned leather. Dynamic light scattering and diffusing wave spectroscopy showed that the aggregation degree of PSD in water increased with the increased pH, the decreased temperature and the increased concentration. Therefore, the retanning of organic tanned leather with PSD was carried out at pH 4 and 40 ℃. PSD could penetrate into the hierarchy of collagen fibrils of the organic tanned leather and form a hydrophobic film, which remarkably improved the hydrophobicity of the crust leather. The penetration time of water increased from 0.14 min to 10-20 min in dynamic waterproofness determination. In addition, PSD promoted the absorption of anionic fatliquor by the organic tanned leather, with the absorption rate increasing from 88.5% to 93.7%. The hydrophobicity and the thickening rate of the crust leather were enhanced, while the softness decreased as the dosage of PSD increased. In summary, the application of cationic amphiphilic copolymers in retanning of organic tanned leather can improve the comprehensive performance of the finished leather, which contributes to developing the chrome-free organic tanning system and producing high-performance metal-free eco-leather.

2024 Vol.34(3): 9–16    [Abstract] ( 3 )    [PDF 1840 KB ] ( 1 )

To enhance the shielding performance of materials without significantly increasing the thickness, barium (Ba) was initially incorporated into the hierarchical structure of natural leather (NL) through the equal volume impregnation strategy (Ba/NL), and the waterborne polyurethane finishing agent with well-dispersed nano-gadolinium-oxide (Gd2O3) was uniformly coated on the grain surface of Ba/NL to fabricate X-ray shielding material (Gd-Ba/NL). X-ray shielding performance results showed that the 1.5-mm-thick Gd1.80-Ba2.32/NL could provide an equivalent level of shielding efficiency to 2.6-mm-thick Ba2.32/NL . The synergistic effect of Gd and Ba contributed to a shielding efficiency exceeding 70% for the X-rays in the energy range of 16-48 keV, and provided a comparable mass attenuation coefficient for the X-rays in the energy of 65 and 83 keV to that of 0.25 mm lead plate. Furthermore, Gd1.80-Ba2.32/NL exhibited several advantages, including superior wearable comfortableness and excellent mechanical strength. Notably, it possessed a density that is only 1/3 of lead apron, while offering a water vapor permeability 12 times higher than that of lead apron. Its tensile strength and tearing strength surpassed national standards by 2 and 3 folds, respectively. Consequently, Gd1.80-Ba2.32/NL holds great potential as a wearable X-ray shielding material capable of replacing traditional lead apron.

2024 Vol.34(3): 17–24    [Abstract] ( 2 )    [PDF 1738 KB ] ( 0 )

The transformation behavior of dissolved organic matter in tannery wastewater is still unclear in biological treatment systems. Herein, tannic acid, glycine and glucose were used as raw materials to simulate the abiotic humification of wastewater. By combining with multivariate spectroscopy, we investigated the characteristics of the abiotic humus products, the transformation and the effects on the metabolic activity of microorganisms in both pure and mixed culture systems. Results showed that tannic acid promoted the abiotic humification process, while the fluorescence intensity of the amino acid-like region was enhanced at 48 h-1 000 mg/L in the pure culture after the microorganisms were exposed to the abiotic humification system. The fluorescence intensity was the strongest in the humic acid-like region at 96 h-2 000 mg/L in the mixed culture, and the fluorescence region of the solubilized microbial by-product-like products was added. Analysis of SUVA254, a measure of the degree of humification, showed that the mixed culture was three times higher than the pure culture, indicating a significant increase in the aromaticity of the transformed abiotic humic products compared to the mixed culture. This work revealed that abiotic humification and its biotransformation products were important control factors governing the standardized treatment of tannery wastewater.

2024 Vol.34(3): 25–30    [Abstract] ( 2 )    [PDF 1358 KB ] ( 0 )

This study aimed to investigate the tanning performance of a newly organic chromium-free tanning agent, EIT AT. The pickled sheepskins were used in the experiment. By using two different tanning systems: conventional pickling and non-pickling, the shrinkage temperature, fiber morphology, and thermodynamic properties of tanned leather were analyzed. The results showed that the change of variations in tanning process has a similar impact on the tanning effect in two different tanning systems. At the 6% amount of EIT AT, the shrinkage temperature of the crust leather can reach above 89 ℃; The crust leather exhibited full grain and clear pores, as well as similar thermal stability and mechanical properties in two different tanning systems. Therefore, the tanning effect of EIT AT tanning agent shows less differences with pickling or non-pickling conditions. The results provide a certain theoretical guidance for the popularization and application of chromium-free tanning technology with EIT AT tanning agent.

2024 Vol.34(3): 31–37    [Abstract] ( 2 )    [PDF 1543 KB ] ( 0 )

The self-repair properties of polyacrylate membrane material were mainly realized through the dual dynamic reversible effect of metal coordination bond and hydrogen bond. A series of polyacrylate emulsions containing metal ions were synthesized through emulsion polymerization. The self-healing polyacrylate membrane material containing metal ions was coordinated with metal ions Cr3+ by the functional group (amide group) on the monomer acrylamide, and the functional group (amide group) on the monomer acrylamide could form reversible hydrogen bonds. It is found that the film has self-healing ability after adding metal ions, and the repair effect is different with different content of metal ions. The best self-healing temperature and the best self-healing time of the film were studied. The tensile test shows that when the content of metal ions was 0.15 g, the tensile strength repair rate of the polymer was up to 80%. The best self-healing time of the film was 12 h, and the best self-healing temperature was 60 ℃. The coordination of metal ions and special functional groups in polymers has made the self-healing materials have excellent mechanical properties and good repair performances.

2024 Vol.34(3): 38–44    [Abstract] ( 7 )    [PDF 1204 KB ] ( 5 )

As the concept of "green development" continues to be promoted, traditional tanning industry is increasingly affected by the pollution generated during its production process. The chromium tanning wastewater and sludge produced by the tanning process pose significant environmental and health hazards if not effectively treated and utilized. Additionally, improper handling leads to substantial waste of chromium resources. The development of economical and efficient chromium treatment and utilization technologies is urgent. This paper introduces various treatment methods for chromium-containing wastewater and sludge produced during the tanning process. These methods include recycling, electrocoagulation, bioleaching, and supercritical water oxidation. Furthermore, it provides a summary and outlook on the development of recycling methods for treating chromium in wastewater and sludge. The aim is to foster a new way of thinking about the development of China's leather industry towards greener practices.

2024 Vol.34(3): 45–50    [Abstract] ( 3 )    [PDF 835 KB ] ( 0 )

As one of the important properties of nonwovens for super-fiber leather, the mechanical properties determine the application range of super-fiber leather. Nonwovens for microfiber leather are mostly prepared from sea-island staple fiber or orange-petal filament superfine fiber by acupuncture or spunlaced reinforcement. From the three factors of fiber raw material, this paper mainly analyzed the fiber strength and elongation at break, fiber linear density, fiber length and fiber curl, acupuncture process, and spunlace process. The influence of needle density, needle depth and spunlace pressure on the mechanical properties of nonwovens provides a reference for enhancing the mechanical properties of nonwovens for ultrafine fiber synthetic leather.

2024 Vol.34(3): 51–57    [Abstract] ( 2 )    [PDF 1259 KB ] ( 0 )

In order to explore the possible effects of different toe spring parameter designs on the biomechanical characteristics of human walking, literature searches were conducted using databases such as PubMed and the China National Knowledge Infrastructure to get articles published over the past 30 years about the influence of the spring parameters on lower limb biomechanics. A total of 486 articles were retrieved, and 16 of them were ultimately included for analysis. The results showed that different design parameters could have an impact on plantar pressure, gait stability, and ankle biomechanics. The apex position can affect ankle dorsiflexion resistance by changing the resistance arm, thereby affecting ankle dorsiflexion torque and subsequently affecting Achilles tendon stress. Altering the forefoot rocker angle could reduce the dorsiflexion angle of the metatarsophalangeal joint, leading to the decreased forefoot plantar pressure. It also helps to mitigate the winding effect and relieve plantar fascia stress. However, smaller apex angles can disrupt gait stability. The benefits of different combinations of parameters for foot and ankle health vary, and it is necessary to further clarify the interactions among these parameters to ensure the application effectiveness of functional footwear design.

2024 Vol.34(3): 58–65    [Abstract] ( 2 )    [PDF 1541 KB ] ( 0 )

A method for simultaneous determination of 9 bisphenols in leather was established by ultra-high performance liquid chromatography-tandem mass spectrometry. The sample was ultrasonically extracted with methanol. The obtained extract was purified by solid phase extraction column and concentrated to constant volume. The filtrated solution was separated by Agilent ZORBAX Eclipse Plus C18 chromatographic column (100 mm×3.0 mm, 3.5 μm), using water-methanol as mobile phases for gradient elution. Multi-reaction monitoring analysis was performed using a quadrupole mass spectrometer, and internal standard method was adopted for quantification. The results showed that the 9 bisphenols could be separated within 9 min, and the good linear relationships were obtained with correlation coefficients R2 all above 0.999 0. The limits of detection and quantification were in the ranges of 0.8-24 μg/kg and 4.0-80 μg/kg, respectively. The average recoveries were 85.2%-105.6% with precisions of 2.6%-10.3%. Bisphenol F, bisphenol S, bisphenol A, bisphenol E and bisphenol AF were detected in the leathers for shoes, with the higher detection rates for bisphenol F and bisphenol S, respectively. With the advantages of convenient operation, high sensitivity and good precision, the method provides a technical support for risk monitoring of bisphenols in leather and leather goods.

2024 Vol.34(3): 66–72    [Abstract] ( 2 )    [PDF 1282 KB ] ( 0 )

The hydrolysis of chromium shavings with subcritical water was studied by single factor experiments and optimized by orthogonal test. The optimized parameters were temperature of 150 ℃, liquid ratio of 25, reaction time of 75 min, and calcium oxide dosage of 6%. Under these conditions, the hydrolysis ratio of chromium shavings was (83.98 ± 0.16)%, and the chromium content of the hydrolysate was (34.81 ± 2.29)mg/kg, which was lower than that of the organic fertilizer standard of the agriculture department. The main components of the hydrolysate were peptides and short peptide as well as a small amount of amino acids. The results indicated that the hexavalent chromium content of the hydrolysate and the solid residue were 1.317 mg/kg and 30.882 mg/kg, respectively, which means most of the chromium (trivalent and hexavalent) mainly exists in the solid residue. The leaching chromium content and the hexavalent chromium content in the solid residue were 14.285 mg/L and 1.544 mg/L, respectively, which were lower than the standard limits of “identification standard for hazardous wastes-identification for extraction toxicity”. These results indicate that subcritical water hydrolysis for chrome shavings is a really harmless treatment and resource utilization.

2024 Vol.34(3): 73–79    [Abstract] ( 2 )    [PDF 1787 KB ] ( 0 )

In the production of parchment paper, unhairing is indispensable. The traditional unhairing with sulfides causes severe pollution. Herein, enzymatic dehairing was used in the production of parchment paper. The research result showed that the unhairing with WB600-KerT enzyme was safe and caused excellent fiber dispersion. The tensile strength and tear strength of enzyme-dehairing parchment were higher than that of sodium sulfide dehairing parchment, and significantly higher than that of cardboard, coated paper and other paper types. Afterwards, enzymatic unhairing parchment exhibited remarkable resistance to light aging. The color change value of enzyme-dehairing parchment paper was significantly lower than that of sulfide-dehairing parchment, cardboard and coated paper. This can be attributed to the fact that, during the UV light continuous radiation, amide bond of enzyme-dehairing parchment paper undergoes a large number of breaks, so that it has a better aging resistance. Additionally, the higher fiber dispersion of the enzymatic unhairing parchment has positive influence on permeability of ink molecules. This results in better paper flatness, smoother writing experience, and improved handwriting clarity compared to sulfide-unhairing parchment.

2024 Vol.34(3): 80–85    [Abstract] ( 2 )    [PDF 1313 KB ] ( 0 )

Unilateral load carrying is often used in daily life and work, which not only increases the load of the feet, but also deviates the bag-plus-body center of mass from median sagittal plane and may cause decreasing the stability. Unilateral load carrying possibly induces a risk of the foot blisters, stress fractures and falls. Fifteen healthy young male undergraduates were asked to walk along an 8-m walkway, stand quietly and look straight ahead of the wall for 30 s. A Footscan 1 m pressure plate and 1 m force platform were used to measure the ground reaction forces and the center of pressure during standing and walking carrying a bag of 7 kg and 14 kg with the right hand respectively. The influence of unilateral loading on the stability, the impact of the foot and the gait were analyzed. Compared to the normal walking, the absolute value of the vertical ground reaction forces increased, its relative value remained unchanged, stability decreased and gait changed in the two loaded condition. It is necessary to increase the cushioning performance of the sole to reduce foot damage and increase the stability of the shoe to reduce the risk of a fall for the functional shoe design for regular unilateral load carrying groups.

2024 Vol.34(3): 86–93    [Abstract] ( 3 )    [PDF 1491 KB ] ( 0 )

To improve the health of women's feet damaged by daily wearing high heels, 40 young women were selected to wear 3 pairs of high heels with full palm midsole material of different hardness. The Footscan® plantar pressure measurement system was used simultaneously with RSscan® force platform to test their gait cycle, center of pressure (COP) and plantar dynamics characteristics including maximum force, peak pressure, and pressure-time integral during natural walking. Results showed that, with the decrease in midsole hardness, the forefoot contact phase (FFCP) became longer, the foot flat phase (FFP) became shorter, the supination degree decreased significantly, and the pronation degree increased significantly. This study has important reference value for improving the comfort and stability of high-heeled shoes, and can provide scientific and reliable theoretical support for the selection and development of high-heeled midsole materials.

2024 Vol.34(3): 94–100    [Abstract] ( 2 )    [PDF 1893 KB ] ( 0 )

As a treasure of traditional folk culture, Nanfeng Nuo mask has a rich artistic heritage and cultural value and shows a unique aesthetic charm. This article explained the characteristics of Nanfeng Nuo mask art form in terms of shape, color and decoration, and analyzed the design ideas and design principles of Nanfeng Nuo mask patterns in handbags. The pattern design of Nanfeng Nuo mask was carried out and the corresponding application was also studied in bags. Using leather goods as a carrier to continue Nanfeng Nuo mask art, its patterns were applied to the modern handbag design. It is hoped to broaden the development idea and the application value of Nanfeng Nuo mask art symbols.

2024 Vol.34(3): 101–107    [Abstract] ( 2 )    [PDF 2080 KB ] ( 0 )

Qiang cross stitch embroidery is the most representative embroidery stitch of the Qiang culture, whose patterns are diverse and rich, and reflect the rich life and cultural connotation of the Qiang people. Herein, the Qiang embroidery patterns were extracted by digital software, and the Shape Grammar Theory was used to optimize the design process to realize the sustainable protection and innovation of the Qiang embroidery patterns. The laser engraving technology was then applied to investigate the suitable parameters and the best presentation effect of the Qiang embroidery patterns when used on different leather materials. The best laser engraving conditions on two types of leather were obtained with the following process parameters: number of markings of 2, engraving line speed of 800 mm/s, Q-frequency of 5 kHz, and laser power of 5 W. The results obtained on vegetable tanned cowhide were more favorable than those on sheepskin. In short, this work realizes the creative transformation and innovative development of leather Garments with cultural characteristics of Qiang cross stitch embroidery pattern from the aspects of material, technique, and fabrication.

2024 Vol.34(3): 108–113    [Abstract] ( 3 )    [PDF 2101 KB ] ( 1 )

This article initiated an active inheritance study of the Qing Dynasty's preserved changyi garments, commencing with the developmental history of changyi and progressively moving towards the progression of changyi design elements, stylistic categorization, pattern characteristics, element extraction, and design application direction. Grounded in the realm of design application, the method and step for extracting changyi design elements were revealed, and the successfully extracted elements were selectively applied in the modern leather apparel design. A in-depth analysis was conducted on design cases, aiming to promote the inheritance and development of traditional culture in modern society, with the expectation of providing a referenceable method and approach for contemporary designers.

2024 Vol.34(3): 114–118    [Abstract] ( 3 )    [PDF 1077 KB ] ( 1 )

Based on the questionnaire survey data of 43 students from 16 colleges of Guangzhou City Institute of Technology, this paper analyzed the foot health and influencing factors of college students from six aspects, namely foot health, foot diseases, mitigation methods, shoe types, shoe selection basis, and the necessity of customized shoes. It is found that there are certain problems in the foot health of college students, and there are obvious gender differences. Gender was positively correlated with shoe size, foot width, foot health and foot diseases, and negatively correlated with shoe type and shoe selection basis. There was a positive correlation between foot diseases and the mitigation method, the basis of shoe selection, and the necessity of customized shoes, but there was a nonlinear relationship with the type of shoes. In this regard, full attention should be paid to the differences in foot health, foot diseases and shoe selection standards of college students, improve the positive guiding role of corrective shoes and corrective footwear, and improve the pertinence of corrective shoe design.

2024 Vol.34(3): 119–124    [Abstract] ( 4 )    [PDF 1068 KB ] ( 0 )

It is an effective channel to achieve the cultivation of inter-disciplinary talents in college by introducing ideological and political elements into professional courses to promote the organic integration of ideological and political education and professional training. The course of leather production practice is a compulsory course of the light chemical engineering major. This paper shares sufficient exploration of ideological and political elements of the course to provide correct value guidance to students, enhance their national self-confidence and upgrade patriotism, and cultivate their sustainable environmental awareness, rigorous and meticulous work attitude, persistent scientific research style and excellent craftsman spirit. The teaching practice of this course not only provides a reference for the reform of ideological and political education of practical professional courses in colleges, but also contributes to the cultivation of socialist builders and successors with all-round development of moral, intellectual, physical, aesthetics and work skills.