May 2017 Abstracts

Fabrication and Characterization of Regenerated Leather Using Chrome Shavings as Raw Materials

by Cuicui Ding, Min Zhang, Libo Dai, Yingying Qi, Ronghui Shi and Junhui Yang

Regenerated leather billet (semi-finished product) was prepared via hot pressing with chrome shaving and environment-friendly polymer waterborne polyurethanes (WPU) as the materials. The influence of WPU/chrome shaving ratios (w/w) on the performance of the billet was investigated by mechanical property test, dynamic thermal mechanical analysis, thermogravimetric analysis, differential scanning calorimetry and field-emission scanning electron microscopy. Furthermore, the ability of heat storage and temperature regulation was endowed for the regenerated leather by the addition of paraffin microcapsules. The results showed that a strong interface interaction could be achieved for the regenerated leather billet, which could be due to the formation of hydrogen bonds and the entanglement between WPU and leather shavings. In this way, WPU/leather shaving composites with favorable mechanical properties, thermal stability, ability of heat storage and temperature regulation were obtained.

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The Relationship Between the Structure of Hyper-branched Polymer and its Effect on High Exhaust Chrome in Reduced Chrome Tanning

by Qi Yao, Chenying Li, Henghui Huang, Hualin Chen and Bailing Liu

DHyper-branched polymer (HBP) has been widely used as pretanning, tanning auxiliary and retanning agent in chrome tanning industry. However the effect of the structure of HBP including the degree of branching (DB) and molecular weight (Mw), on chrome tanning has seldom been studied. In this study a series of carboxyl-terminated hyper-branched oligomer (HBP) with different DB and Mw have been prepared and characterized by GPC and 1H-NMR for determining their molecular weight and its distribution, as well the DB. The effect of DB and Mw on the chrome uptake and shrinkage temperature (Ts) of hide was investigated. Experimental results showed that the chrome uptake was affected by both DB and Mw of developed HBP. HBP that possesses high DB and the Mw closed to 2000 Da, has endowed the obtained leather with higher Ts and chrome uptake. Moreover, the leather tanned with 3% chrome and 1.5% HBP possesses similar properties to the traditional tanning process using 6-8% chrome. Therefore, the carboxyl-terminated HBP presents a potential application as a tanning auxiliary in reduced chrome tanning due to it’s improving the absorption of chrome.

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Zinc Oxide (ZnO) Nanoparticles for Enhancement of Fastness Properties in Cationic Finishing

by RamKumar Kothandam, R.Jayavel and Sanjeev Gupta

Zinc oxide (ZnO) nanoparticles were synthesized by precipitation technique and used along with cationic finishes to improve the wet rub fastness properties and flexing resistance of coated leather. The morphology, composition, and structure of the ZnO nanoparticles were analyzed using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). ZnO nanoparticles were dispersed in water and incorporated in different ratios in conventional Nitrocellulose lacquer emulsion topcoat formulation was coated on the leather surface by spray coater. ZnO nanoparticles coated leather samples exhibited improved wet and dry rub fastness and flexing resistance property. Optimum quantity up to 2-4 g/L of ZnO nanoparticles in the season was desirable for upgrading the value of leathers. ZnO nanoparticles in cationic finishing can be highly beneficial for up gradation of low-grade crust with improved fastness properties without affecting its natural look and feel.

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Determination of Formaldehyde Content in Leather: EN ISO 17226 Standard. Influence of the Agitation Method Used in the Initial Phase of Formaldehyde Extraction

by Albert M Manich, Sara Cuadros, Joaquim Font, Anna Bacardit, Felip Combalia and Agustí Marsal

Given the carcinogenic character of formaldehyde, it should be reliably determined in any substrate. The EN ISO 17226 Standard is the Official Method to quantify formaldehyde in leather. However, some misunderstandings may arise from the practical conditions given by the Standard for the extraction of formaldehyde. Two agitation methods (magnetic agitation and reciprocal linear agitation), which fulfill the conditions of the Standard, have been used for the extraction of formaldehyde in twenty two samples of wet-blue split leather treated with resins synthesized with formaldehyde and with/without the addition of vegetable compounds. The agitation method influences the formaldehyde content and differences between the agitation methods depend on the formaldehyde resins and vegetable compounds applied. Magnetic agitation leads to formaldehyde contents that are 26% greater than those obtained when the reciprocal linear agitation method is used. Major brands specify allowable limits for formaldehyde content, which depend on the user (adult or babies) and whether the article is in direct contact with the skin. A high percentage of disagreement (33.3%) has been observed between the agitation methods in fulfilling the allowable limits. One-third of the formaldehyde content results that fulfilled the allowable limits with the reciprocal linear agitation method failed when the magnetic method was applied. The situation urges the clarification of the shaking method in the EN ISO 17226 Standard to avoid the high level of contradictory results between methods that meet the agitation conditions of the Standard.

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