Comparative retanning performance of ecofriendly melamine resins produced using different condensing agents / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 105, N° 3 (05-06/2021)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 105, N° 3 (05-06/2021) . - p. 140-152 Titre : Comparative retanning performance of ecofriendly melamine resins produced using different condensing agents Type de document : texte imprimé Auteurs : Muhammad Naveed Ashraf, Auteur ; Shahzad Maqsood Khan, Auteur ; Shahid Munir, Auteur ; Rashid Saleem, Auteur Année de publication : 2021 Article en page(s) : p. 140-152 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux -- Propriétés organoleptiques Mélamine sulfonée Mélamine La mélamine, de nom chimique 1,3,5-triazine-2,4,6-triamine, est parfois dénommée cyanuramide ou cyanurotriamine. Sa formule brute est C3H6N6. Les "résines mélamine-formaldéhyde" ou "mélamine-formol" (sigle MF) sont appelées "mélamine" dans le langage courant. Elles font partie de la famille des aminoplastes qui regroupe des résines thermodurcissables aminées, issues d'un comonomère tel l'urée ou la mélamine, parfois le thiocarbamide, le cyanamide hydrogène ou le dicyandiamide ; le second comonomère étant le formaldéhyde. Produits de condensation (chimie) Retannage Tannage synthétique Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Formaldehyde has been a famous raw material for production of amino resins used in leather processing however; the proven carcinogenic hazards of formaldehyde contravene regulations are restricting the sale of leather goods with regard to human contact. In this study sulfonated melamine based resins were produced by using condensing agents other than formaldehyde, for example furfural, glyoxal, methylglyoxal and glutaraldehyde. Synthesised formaldehyde-free melamine resins were studied for determination of their molecular weights, thermal stability by TGA and spectroscopic studies using FTIR. Synthesised resins were used in leather retanning for investigation of their mechanical and organoleptic properties in comparison with leather samples based on a commercial resin. The effects of melamine resins on the fibrous structure of collagen were examined by SEM. Leather pieces were analysed for estimation of free formaldehyde contents and the pollution load of the retanning wastes was also investigated. The prepared resins conferred improved mechanical and organoleptic characteristics to the resulting leather compared to the control but the results produced by MGLSNA and MGSNA resins were more prominent. Leather produced from each resin sample was formaldehyde free. SEM images of the leather revealed the presence of fine grains with improved fibrous collagen structure especially for MGLSNA and MGSNA. Pollution load reduction efficiency of newly developed resins was improved in comparison with control indicating their better uptake and fixation in collagen fibres. Overall, all four novel resins produced formaldehyde-free leather with improved retanning and thermal properties but the results produced by MGLSNA and MGSNA resins were better due to introduction of more reactive sites and aromatic sulfonation agents. Note de contenu : - EXPERIMENTAL PROCEDURE : Chemicals and apparatus - Synthesis of sulfonated melamine resins - RESULTS AND DISCUSSION : Synthesis of sulfonated melamine resins - Physical characteristics of sulfonated melamine resins - Molecular weight determination of sulfonated melamine resins - Comparative application of sulfonated melamine resins on leather - Mechanical properties of leather retanned with sulfonated melamine resins - Organoleptic properties of leather retanned with sulfonated melamine resins - Characterisation of retanned leather by SEM - Determination of free formaldehyde content in leather - Thermo gravimetric analysis of sulfonated melamine resins - FTIR analysis - Wastewater analysis of retanning bath - Table 1 : Mole ratio and physical characteristics of sulfonated melamine resin prepared with different condensing agents - Table 2 : Dependence of the flow time, relative viscosity, specific viscosity, δ = ηsp - inηr and δ/c2 at different concentrations of SMFr resin - Table 3 : Dependence of the concentration of novel resins of study on δ/c2 - Table 4 : Leather processing recipe, materials and conditions - Table 5 : Mechanical properties of leather retanned with sulfonated melamine resins - Table 6 : Comparative pollution load efficiency of sulfonated melamine resins En ligne : https://drive.google.com/file/d/1N5Wt_oi9uVzToJ_7z1L_jwRfqTgOlm5M/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35834 [article]

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