Particle size evolution of melamin-formaldehyde tanning agent on tanning effect / Mengmeng Chen in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIII, N° 5 (05/2018)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIII, N° 5 (05/2018) . - p. 151-162 Titre : Particle size evolution of melamin-formaldehyde tanning agent on tanning effect Type de document : texte imprimé Auteurs : Mengmeng Chen, Auteur ; Yahui Wang, Auteur ; Haojun Fan, Auteur ; Yi Chen, Auteur ; Jun Yan, Auteur ; Yu Liu, Auteur Année de publication : 2018 Article en page(s) : p. 151-162 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage Copolymère mélamine-formaldéhyde Cuirs et peaux -- Propriétés mécaniques Polycondensation Stabilité hydrothermale Taille des particules Tannage organique Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Melamine-formaldehyde [MF] resin is a tanning agent. Its average particle size [PS] is important for penetrating the skin and thus endowing performance of its resultant leather. The synthesis parameters for MF resin such as pH, molar ratio of formaldehyde to melamine, temperature and reaction time affect its PS. We investigated in detail the growth of MF’s PS and its consequent effects on hydrothermal stability, mechanical properties and the apparent properties of leather. The data showed that a broad range of average PS was formed at the different synthesis stages of MF resin. For example, the first reaction stage of methylolation gave an average particle diameter of 250 nm with a narrow size distribution under the conditions of 45°C, 3:1 molar ratio, a pH of 8.5, and a reaction time of 3 hrs. In this case the resultant leather was poor as it had a low shrinkage temperature, lacked fullness and showed a low-valued elongation at break. During the second polycondensation stage, the PS of MF resin increased with increasing reaction temperature and the molar ratio of formaldehyde to melamine. Furthermore, PS increased more rapidly by lowering the pH of the polycondensation and extending its reaction time. Thus, the new average diameter of MF resin particles reached above 3000 nm when the polycondensation reaction was done inside the skin for 2 hours at a pH of 4.5. Consequently, the resultant leather was white and full. It had a high hydrothermal stability and mechanical strength as evidenced by its fully satisfactory elongation at break. Clearly, the cross-links were formed by multiple site interactions between MF resin with large PS and collagen fibers, which enhanced the tanning effect. Note de contenu : - EXPERIMENTAL : Materials - Reaction of melamine and formaldehyde - Tanning trial - Assessment of properties of tanned leathers - RESULTS AND DISCUSSION : Parameters affecting the particle size of MF resin tanning agent - The effect of tanning agent's PS on properties of tanned leather En ligne : https://drive.google.com/file/d/1nqOi07mAnm5Xjiy0M0yrCKEJqM67qm-7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30533 [article]

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