Contribution to assessing cross-linking of protein hydrolyzate with diepoxides / J. Hrncirik in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CII, N° 12 (12/2007)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CII, N° 12 (12/2007) . - p. 393-403 Titre : Contribution to assessing cross-linking of protein hydrolyzate with diepoxides Type de document : texte imprimé Auteurs : J. Hrncirik, Auteur ; J. Pseja, Auteur ; J. Kupec, Auteur ; M. Tupy, Auteur Année de publication : 2007 Article en page(s) : p. 393-403 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : This work summarizes the influence exerted on cross-linking of protein hydrolyzate obtained through enzymatic hydrolysis of chrome-tanned leather shavings, by means of diepoxides (1,2:3,4 diepoxybutane and 1,2:7,8 diepoxyoctane). Attention was given to preparation of cross-linked samples, their solubility, intrinsic viscosity and IR spectra. Suitable conditions for cross-linking were found at pH = 9 and 25˚ C temperature. Solubility of samples decreased proportionately with increasing concentrations of cross-linking agent. Viscosity measurements yielded best results in 1M KCl solution. Determining intrinsic viscosity indices proved this value was influenced more by the approach of the gelation point than by the epoxide content. IR spectra demonstrated that in the region of wave numbers 838, 912 and 1,250 cm-1, peaks of epoxide groups of employed pure cross-linking agents coincide with similar peaks of other groups of cross-linked samples; peaks of epoxide bonds at the mentioned wave numbers are discernible only with highest employed concentrations of cross-linking agents. Future research will address examining various epoxy groups, employing di- or multifunctional amines and determining critical gelation conversions and critical stoichiometric ratios of defined substances. En ligne : https://drive.google.com/file/d/1FrqqGPZyQdgm9I3ga_nynP9S_tYxkhHl/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3316 [article]

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Kinetics of alkaline hydrolysis of the insoluble protein fraction following enzymatic hydrolysis of chrome-tanned shavings / J. Hrncirik in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 1 (01/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 1 (01/2005) . - p. 1-7 Titre : Kinetics of alkaline hydrolysis of the insoluble protein fraction following enzymatic hydrolysis of chrome-tanned shavings Type de document : texte imprimé Auteurs : J. Hrncirik, Auteur ; Karel Kolomaznik, Auteur ; J. Kupec, Auteur ; F. Hruska, Auteur ; M. Dvorackova, Auteur Année de publication : 2005 Article en page(s) : p. 1-7 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The problem of using chrome-tanned wastes (namely shavings) has been the subject of a number of reports. One path is enzymatic hydrolysis with possible utilization of both the protein fraction as well as chromium. After hydrolysis and subsequent filtration, a so-called filter (or chrome) cake is formed, which is composed of hydrated Cr2O3 heavily contaminated with protein products of hydrolysis (removable, e.g. in washing) as well as with a non-hydrolysable fraction. The fraction requires breaking down, e.g. with strong alkali, as was performed in tests conducted to provide data for evaluating hydrolysis kinetics. Applying a number of simplifying assumptions, efforts were directed to expressing formal kinetics of this alkaline hydrolysis with a KOH solution. According to calculations, the reaction appears to agree well with a second-order reaction, with effective values of rate constant c = 3.9.10-3 l/(mol.s) and activation energy Ea = 130 kJ/mol at hydrolysis temperature of 116°C. En ligne : https://drive.google.com/file/d/1oU3ce67tRFLR-MZNtxcMLIOJrrgMn2wP/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4084 [article]

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