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Ajouter le résultat dans votre panierRisk assessment of leather dyestuffs / Alois Püntener in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 82, N° 1 (01-02/1998)
Titre : Risk assessment of leather dyestuffs Type de document : texte imprimé Auteurs : Alois Püntener, Auteur Année de publication : 1998 Article en page(s) : p. 1-4 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Colorants -- Analyse du cycle de vie
Colorants -- Aspect de l'environnement
Cuirs et peauxIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Public interest is increasingly focused on leather goods and the potential risks to our health and the environment arising from them. Although these hazards are not substantiated by any etablished findings, the media seize on them and often paint a very alarmist picture in their stories.
Fortunately, the real picture is not all black, there are also some positive aspects. The leather industry is making considerable progress in improving its environmental performance. This paper will look at risk and life-cycle assessment of leather dyes.
The identification of humanhealth and environmental hazards are important prerequisites for risk and life cycle assessment. Good quality information on exposure is needed to address the risk objectively, and possible options for risk reduction. Risk management should indeed start with a careful selection of colorants that exhibit the required performance with regard to substrate affinity, fastness and other boundary conditions.
The environmental risk posed by a colorant can be defined in both its inherent ecotoxicity and the concentrations attained in the environmental compartments. There is an increasing body of circumstantial evidence indicating that the portion of colorants entering the environment is ultimately degradable either by biological or photochemical pathways.Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7934
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 1 (01-02/1998) . - p. 1-4[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 007020 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Molecular modelling of tanning processes Type de document : texte imprimé Auteurs : Jens Fennen, Auteur Année de publication : 1998 Article en page(s) : p. 5-10 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : During the past decade molecular modelling techniques have been a field of major research. The underlying theory has been refined, modelling programs have become both faster and more reliable, additionally computer power has increased enormously. The main focus and driving force of the application of these tools has so far been in the area of drug design. Although results have not always been up to expectations, molecular modelling can now be considered to be one of the standard tools in pharmaceutical research.
With this palette of modelling tools at hand, it seems promising to investigate the chemical nature of tanning processes at a molecular level. Starting from results obtained at the Eastern Regional Research Center, USDA, Philadelphia, the paper presents the development of a model for bovine collagen type I in aqueous medium and its refinement with the m olecular dynamics method.
Density functional theory (DFT) methods were used to calculate the structure of a model chrome complex as it is believed to be formed during the process of chrome tanning. The positions of reactive sites in the collagen model are finally compared with the dimensions of the chrome complex model and show a good fit.
It will then be discussed what else might be achieved by molecular modelling in the field of leather chemistry after a promising stard and which problems still have to be solved. The question of the size of an appropriate model which should reproduce macroscopic effects will especially be adressed.Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7935
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 1 (01-02/1998) . - p. 5-10[article]Réservation
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Titre : Scanning probe microscopy. A useful tool in leather research Type de document : texte imprimé Auteurs : G. Reich, Auteur ; T. Taeger, Auteur ; W. Pompe, Auteur ; M. Mertig, Auteur ; J. Bradt, Auteur Année de publication : 1998 Article en page(s) : p. 11-14 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Optical microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are widely accepted investigation methods in fundamental and applied leather research. They are under further development, for instance by cryotechnique (cryomicroscopic SEM), rotary shadowing-TEM, use of confocal laser sanner and computer aided microscopy in general. The further possibilities and the limits of this method are physically substantiated and illustrated.
Currently, novel methods of scanning probe microscopy have attracted special attention in physics, chemistry, material science and biology, because they can resolve surface details down to atomic level. Especially, scanning for microscopy (SFM) shows the capability to image isolating surfaces, including biological specimens and coatings, with nanometer resolution. The main advantages for applications in biology are : the possibility of working in a liquid environment under physiological conditions, to get three-dimensional topographic information and the possibility of probing local forces e.g. to obtain information about the mechanical properties of the investigated specimen.
We have carried out SFM of leather. The investigations started with collagen monomers and collagen fibrils immobilized as different substrates. So far the best resolution we could achieve is to image rod-like individual collagen monomers with a diameter of 1.6 nm and the 67 nm-periodicity of native type I collagen fibrils. Several fibrils are twisted into bundles in the form of a right-handed matrix. Changes in fibril morphology after calcification have been investigated. The results show that mineralisation occurs with higher density mainly at crossover regions of collagen fibrils. It has been found that the formed hydroxyapatite crystallites are similar in size, typically between 50 and 100 nm.
Investigation on leather samples after various treatments demonstrate that the applied method is also suited to investigate more complex samples. The advantage of SFM in comparison to SEM is the possibility of use to investigate wet samples and to obtain topographic information with high imaging value.
In conclusion scanning probe microscopy, especially the scanning force microscopy (SFM), is recommended as an useful tool in leather research in addition to the traditional microscopic investigation methods.Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7936
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 1 (01-02/1998) . - p. 11-14[article]Réservation
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Titre : Minimising the environmental impact of chrome tanning : the "thrublu" process Type de document : texte imprimé Auteurs : Samir Das Gupta, Auteur Année de publication : 1998 Article en page(s) : p. 15-21 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The commercial chrome tanning of hides and skins complies with conventional understanding and is carried out at pH 2.5 to 4.0. The efficiency of chrome utilisation in many standard systems is between 75-85 %. There are proprietary systems that can be used to increase chrome utilisation but even these options leave chrome in the trade waste discharge and problems of meeting stringent limits remain. The research reported in this paper seeks to minimise the environmental impact of chrome tanning by changing the basis of present chrome tanning technology.
A novel chrome tanning technique for tanning lamb pelts and lime split hides has been developed whereby pickling is completely eliminated and tanning conducted immediately after deliming at pH 7 to 8.8. This novel technique also does not require basification or masking agents for the completion of chrome tanning. This new approach gives a high exhaustion of chrome to be extent of 98 % for lamb and over 99 % for hides with improved yield of leather at reduced cost. Substantial amounts of salt are eliminated from the process and reduced acid usage encourages lower levels of plant and equipment corrosion.
The study has investigated the reactivity of a standard chrome tanning solution by examining the individual reactivities of the constituent complexes inrelation to their charge characteristics.
Development of the novel no-pickle chrome tanning system has demonstrated that the differently charged ionic complexes can all provide a contribution to the tannage,as measured by chrome uptake from solution, and maintain commercially acceptable properties.
A mechanism suggested for the effectiveness of the no-pickle tannage is based on providing a wider pH range for the complex-substrate interaction and reversing the conventional pH trend by starting at elevated pH and allowing the intrinsic acidity of the chrome tanning reagent to reduce the pH to conventional levels.
The no-pickle process has been evaluated in bulk production trials and its advantages confirmed. In a further extension of this research, where pretannage for aqueous degreasing is concluded at elevated pHs that conventionally have required re-acidification for chrome tannage, it has been shown that pH adjustment is unnecessary both in terms of re-acidification and basification.Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7937
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 1 (01-02/1998) . - p. 15-21[article]Réservation
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Titre : 2-(thiocyanomethylthio)-benzothiazole fungicide on leather : a review Type de document : texte imprimé Auteurs : L. Muthusubramanian, Auteur ; R. B. Mitra, Auteur ; V. S. Sundara Rao, Auteur Année de publication : 1998 Article en page(s) : p. 22-23 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Ten years ago the predominant fungicides used in the leather industry were phenolic based. The availability of these products changes as new active ingredients become available and as other products are considered usuitable on environmental and health and safety grounds (often prohibited by legislation in specific countries). As a result of legislation limiting the content of pentachlorophenol (PCP) in leather, fungicides based on substituted benzothiazole activities such as 2-(thiocyanomethyltio)-benzothiazole (TCMTB) were introduced and became more widely used. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7940
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 1 (01-02/1998) . - p. 22-23[article]Réservation
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| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
|---|---|---|---|---|---|
| 007020 | - | Périodique | Bibliothèque principale | Documentaires | Disponible |
