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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Comparative study of retanning properties of melamine-glyoxal resins produced by different sulfonating agents / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 106, N° 5 (09-10/2022)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 106, N° 5 (09-10/2022) . - p. 205-214 Titre : Comparative study of retanning properties of melamine-glyoxal resins produced by different sulfonating agents Type de document : texte imprimé Auteurs : Muhammad Naveed Ashraf, Auteur ; Shahzad Maqsood Khan, Auteur ; Shahid Munir, Auteur ; Rashid Saleem, Auteur Année de publication : 2022 Article en page(s) : p. 205-214 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composés organiques -- Synthèse Cuirs et peaux -- Propriétés mécaniques Eaux usées -- Analyse Etudes comparatives Mélamine glyoxal Retannage Tannage synthétique Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Amino resins have many applications including leather retanning. Being condensation products of formaldehyde, amino resins are one of the sources of free formaldehyde in leather. ln this work novel glyoxylated melamine resins were produced to make formaldehyde-free leather. The optimised process of synthesis was used to produce stable resins which were able to polymerise further in situ at retanning pH conditions. Water solubility of the resins was achieved by using various aromatic sulfonating agents including, orthanilic acid (ONA), metanilic acid (MNA), sulfanilic acid (SNA) and aniline 2,5-disulfonic acid (ADS). Synthesised resins were used in leather retanning to evaluate their comparative mechanical properties, organoleptic properties, free formaldehyde content and SEM analysis. The effluent of each retanning bath was also analysed for pollution load studies. All the resins showed improvements in mechanical and organoleptic properties in comparison with a commercial melamine resin but, the novel resin MGSNA exhibited remarkable results. Estimation of free formaldehyde content showed absence of free formaldehyde content in leather and retanning effluent of all the novel resins. Determination of COD, TDS and TSS of effluent confirmed a significant reduction in pollution load due to improved exhaustion of resins attributed to their in-situ polymerisation in collagen fibres to enhance their fixation. SEM analysis of leather confirmed improvements in retanning results due to formation of more orderly arranged networks of collagen fibres. Moreover, the introduction of an aromatic ring in the resin structure resulted in improved thermal stability of the resins. The results indicate that this development is remarkable for production of formaldehyde-free leather with improved retanning properties along with reduction in water pollution. This work also addresses the carcinogenic effects of formaldehyde. Note de contenu : - EXPERIMENTAL PROCEDURE : Chemicals and apparatus - Synthesis of novel melamine-glyoxal resins - RESULTS AND DISCUSSION : Synthesis of resins - Leather applications of various novel glyoxal based melamine resins - Mechanical properties of leather reatanned with glyoxal-based melamine resins - Orgnoleptic properties of the leather retanned with glyoxal-based melamine resins - SEM analysis - Quantitative estimation of free formaldehyde content in retanned leather - Thermogravimetric analysis - Effluent analysis - Structural elucidation - Table 1 : Mole ratio and physical characteristics of prepared novel melamine resins - Table 2 : Leather processing materials, conditions and recipe - Table 3 : Mechanical properties of leather retanned with glyoxal based melamine resins - Table 4 : Comparative study of effluent produced from retanning baths of synthesised resins En ligne : https://drive.google.com/file/d/1d731nM2Y_RzuR-xX0DT3EX7AtII9e3uS/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38195 [article]

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Preparation and application of metanilic acid modified ecological melamine resins for making formaldehyde-free leather / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 106, N° 3 (05-06/2022)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 106, N° 3 (05-06/2022) . - p. 126-136 Titre : Preparation and application of metanilic acid modified ecological melamine resins for making formaldehyde-free leather Type de document : texte imprimé Auteurs : Muhammad Naveed Ashraf, Auteur ; Shahzad Maqsood Khan, Auteur ; Shahid Munir, Auteur ; Rashid Saleem, Auteur Année de publication : 2022 Article en page(s) : p. 126-136 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux -- Propriétés organoleptiques Formaldéhyde -- Suppression ou remplacement 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. Retannage Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The objective of this study is to develop a novel melamine based resin suitable for producing formaldehyde-free leather with improved retanning properties. A series of resins was prepared by condensation of melamine, glyoxal and metanilic acid at varied mole ratios of reactants. Prepared resins were evaluated for retanning performance in leather in comparison with a commercial melamine resin to select the optimal resin. The mechanical and organoleptic properties of the optimal resin were found to be better than those of the commercial melamine resin. Tensile strength, tear strength and elongation of leather were increased by 17.43 %, 10.41 % and 8.62 % in direction parai lel to backbone while the increase in these parameters was 15.17 %, 9.79 % and 6.0% respectively in direction perpendicular to the backbone at same dosages. 100% reduction of free formaldehyde content was apparent in retanned leather and in the effluent produced by novel melamine resin. Pollution load study of the effluent showed a reduction in chemical oxygen demand, total suspended solids and total dissolved solids by 9.21 %, 5.60 % and 6.97 % for the novel melamine resin reflecting its improved exhaustion. The fibre structure of the leather produced using the optimal melamine resin was arranged in a more orderly pattern as confirmed by scanning electron microscopy, thus showing its improved retanning capability. These results prove that the optimal melamine resin is an effective retanning agent suitable for producing formaldehyde-free leather with a reduction in effluent pollution load. This work also presents an alternative for formaldehyde for amino resins to address its carcinogenic effects. Note de contenu : - EXPERIMENTAL PROCEDURE : Chemicals and apparatus - Synthesis of metanilic acid modified melamine-glyoxal resins - RESULTS AND DISCUSSION : Schematic route - Leather application of resins as retanning agent - Mechanical characteristics of retanned leather - Effect of melamine resins on organoleptic properties - SEM analysis - Quantitative determination of ree formaldehyde contents in leather - Thermogravimetric analysis (TGA) - FTIR analysis - Effluent analysis - Table 1 : Mole ratio and physical characteristics of synthesised MGMNA resins - Table 2 : Leather processing recipe conditions - Table 3 : Mechanical characteristics of leather retanned with novel MGMNA resins and commercial resin - Table 4 : Comparative characteristics of effluent for leathers retanned with novel resin MGMNA#09 and commercial melamine resin En ligne : https://drive.google.com/file/d/1VlBcJdgglhf3cE0A5J6OugVIVuK_otgv/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37757 [article]

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Preparation of formaldehyde-free melamine resins using furfural as condensing agent and investigation of their retanning performance / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 103, N° 5 (09-10/2019)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 103, N° 5 (09-10/2019) . - p. 272-278 Titre : Preparation of formaldehyde-free melamine resins using furfural as condensing agent and investigation of their retanning performance Type de document : texte imprimé Auteurs : Muhammad Naveed Ashraf, Auteur ; Shahzad Maqsood Khan, Auteur ; Shahid Munir, Auteur ; Rashid Saleem, Auteur Année de publication : 2019 Article en page(s) : p. 272-278 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuir -- Teneur en formaldéhyde Cuirs et peaux -- Analyse Cuirs et peaux -- Propriétés organoleptiques Furfural 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. Polymères -- Synthèse Produits de condensation (chimie) Retannage Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Sulfonated amino resins are an important class of polymers which are used as retanning agents in the leather industry. There is challenge for such resins to be synthesised without formaldehyde to satisfy the strict regulation in leather goods. In this work, formaldehyde-free melamine based retanning agents have been synthesised by acid catalysed process using furfural as condensing agent and sodium metabisulfite as the sulfonating agent. Sulfonated melamine furfural (SMFr) resins were synthesised using different molar ratio of melamine, sodium metabisulfite and furfural. Stable and water-soluble resins were produced without etherification. The sodium metabisulfite to melamine ratio (SMB/M) was changed from 0.5-2.0 and furfural to melamine mole ratio (Fr/M) was varied from 2-6. The viscosity behaviour of the produced resins wâs evaluated with the increasing trend of sulfonation and increasing mole ratio of furfural to melamine. Functional group analysis and conversion of reactants into product was elucidated by FTIR. Synthesised formaldehyde-free resins (SMFr) were comparatively evaluated as retanning agents on goatskin wet-blue against a commercially available sulfonated melamine formaldehyde (SMF) resin. The retanning performance of synthesised resins was studied and found better than that of the commercial SMF resin. Note de contenu : - EXPERIMENTAL PROCEDURE : Materials and equipment - Preparation of SMFr resin - RESULTS AND DISCUSSION : Synthesis of SMFr resin - Viscosity trend of resins - Resin application on leather as retanning agent - Quantitative determination of free formaldehyde content in leather - Organoleptic properties of retanned leather - SEM examination (JEOL 6490) - Structure elucidation/FTIR spectroscopy analysis of SMFr resin En ligne : https://drive.google.com/file/d/1tehL2heU-liowrx614fHL9jzpSdLCcXB/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33003 [article]

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Preparation of sulfonated carbohydrazide-glyoxal based retanning agent and its use in manufacture of sustainable leather / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 105, N° 6 (11-12/2021)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 105, N° 6 (11-12/2021) . - p. 298-306 Titre : Preparation of sulfonated carbohydrazide-glyoxal based retanning agent and its use in manufacture of sustainable leather Type de document : texte imprimé Auteurs : Muhammad Naveed Ashraf, Auteur ; Rashid Saleem, Auteur Année de publication : 2021 Article en page(s) : p. 298-306 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Agents de tannage Carbohydrazide glyoxal sulfoné Composés organiques -- Synthèse Cuirs et peaux -- Propriétés mécaniques Fourier, Spectroscopie infrarouge à transformée de Microscopie électronique à balayage Réticulation (polymérisation) Rhéologie Thermogravimétrie Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Amino resins used in leather processing are produced from formaldehyde which is a carcinogenic species. Such resins may tend to release free formaldehyde in leather thus making it objectionable. The current study is designed to produce formaldehyde-free retanning agents by using carbohydrazide as an amino moiety and glyoxal as a condensing agent. Moreover, hydrophilic properties were achieved by sulfonating the resins with sulfamic acid. A series of resin samples were synthesised by reacting these products at varied mole ratios. The synthesised resins were tested for their viscosity measurements and also characterised by FTIR, TGA and SEM analysis. Sulfonated carbohydrazide based resins produced in this study were comparatively evaluated for their retanning properties in comparison with a commercial amino resin as a control. The results for retanning properties showed that there was a significant improvement in the mechanical and organoleptic properties of leather produced by the experimental resins as compared to the control. SEM analysis of the retanned pieces of leather reflected the improved cross-linking of collagen fibres and uniform filling of experimental resin in grain and fibre structure. FTIR studies for functional group analysis were carried out and TGA was run to evaluate the thermal stability of experimental resins. Estimation of free formaldehyde content in leather confirmed its 100% reduction for experimental resins whereas 143mg/kg formaldehyde was noted for the control resin. Free formaldehyde was also absent in effluents of the experimental resin whereas 273mg/kg formaldehyde was detected in effluent received from control resin. Moreover, percentage reduction of pollution load like COD, TDS and TSS of retanning effluent was observed as 12.60, 10.71 and 8.82 respectively for the experimental resin. The carbohydrazide based resin produced in this study was formaldehyde-free and useful in making green leather with improved retanning properties. Note de contenu : - EXPERIMENTAL PROCEDURE : Chemicals and apparatus - Preparation of sulfonated carbohydrazide-glyoxal resin - RESULTS AND DISCUSSION : Schematic route of synthesis - Rheology of resins - Evaluation of retanning properties of CHG resins - Mechanical properties of leather treated with sulfonated CHG resins - Organoleptic properties of the leather treated with sulfonated CHG resins - Comparative SEM examination of leather - Quantitative estimation of free formaldehyde content in treated leather - Structural elucidation of sulfonated CHG resin - Comparative thermo gravimetric analysis of sulfonated CHG resin - Analysis of effluent - Table 1 : Mole ratios and physical characteristics of prepared CGH resins - Table 2 : Leather processing recipe and conditions - Table 3 : Mechanical characteristics of leather retanned with sulfonated CHG resins - Table 4 : Comparative pollution load reduction efficiency of sulfonated CHG resin #07 En ligne : https://drive.google.com/file/d/15OdJxO3LxljeKGpNmqS9lAz3ecXlVJQa/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36722 [article]

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Synthesis and application of eco-friendly amino resins for retanning of leather under different conditions / Rashid Saleem in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 99, N° 1 (01-02/2015)  

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Synthesis, characterisation and application of environment friendly polymers for producing sustainable leather / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 105, N° 1 (01-02/2021)  

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Synthesis, characterization and application of sulphite castor maleic adduct as an effective leather fatliquor / Muhammad Imran-Ul Haq in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 100, N° 5 (09-10/2016)  

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Synthesis of aniline 2,5 disulfonic acid modified ecofriendly melamine resins and their performance evaluation as leather retanning agents / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 104, N° 5 (09-10/2020)  

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Synthesis of formaldehyde free amino resin to produce green eco-labelled leather with improved retanning properties / Muhammad Naveed Ashraf in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 4 (04/2020)  

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Synthesis of orthanilic acid modified glyoxylated melamine resin with improved retanning and thermal properties / Muhammad Naveed Ashraf in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 103, N° 3 (05-06/2019)

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Viscosity and retanning properties of isophthalic dihydrazide based amino resins under different reactant conditions / Rashid Saleem in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 97, N° 5 (09-10/2013)  

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