Development of reference materials for inorganic elements in leather powder / Qian Wang in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 102, N° 6 (11-12/2018)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 102, N° 6 (11-12/2018) . - p. 304-311 Titre : Development of reference materials for inorganic elements in leather powder Type de document : texte imprimé Auteurs : Qian Wang, Auteur ; Chao Wei, Auteur ; Liandi Ma, Auteur Année de publication : 2018 Article en page(s) : p. 304-311 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse spectrale Chimie analytique Composés inorganiques Cuirs et peaux -- Analyse Poudre de cuir Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Three reference materials for As, Cd, Co, Cu, Hg, Ni, Pb and Sb - 8 inorganic elements in leather powder were developed with relatively low, middle and high concentrations. The reference materials were prepared by adding an appropriate concentration using industrial process. The concentration range of the three levels is within the +/- 200% of the limited value in the China statute Safety Technical Specifications for Children's Footwear (GB 30585-2014). By using 16 units with duplicate analysis, it was shown that the samples were enough to demonstrate the homogeneity of these candidate reference materials. The statistical results from the stability test, also showed no significant trends in both short-term stability test for one week at 40°C and long-term stability test for 23 months. This set of reference materials, were used for more than two certification methods - including isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS), inductively coupled plasma mass spectroscopy (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The combined relatively standard uncertainties of the reference values were estimated by considering the uncertainties of the analytical methods, homogeneity and stability. The range of the expanded uncertainties of all the elements is from 3% to 5%. The certified reference materials (CRMs) are primarily intended for use in the calibration and validation of procedures for the determination of inorganic elements in leather or similar leather samples. Note de contenu : - Instrumentation - Reagents and standards - Preparation of candidate materials - Homogenity - Stability monitoring - Moisture content correction - Measurement methods for certified values and relative uncertainty - ID-ICP-MS (Cd, Cu, Hg, Ni, Pb, Sb) - ICP-MS (8 elements) - ICP-OES (8 elements) - Determination of standard values - Uncertainty evaluation - Uncertainty (uc) due to characterisation process - The combined standard uncertainty - Expanded uncertainty En ligne : https://drive.google.com/file/d/1iIR1yv69vTVvjgM16Zbw4-JT5X3dSASE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31336 [article]

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The preparation of hybrid trimer by cyclo-oligomerization of TDI and HDI and its curing process with polyols to form elastic PU coating / Qian Wang in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 14, N° 6 (11/2017)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 14, N° 6 (11/2017) . - p. 1279-1288 Titre : The preparation of hybrid trimer by cyclo-oligomerization of TDI and HDI and its curing process with polyols to form elastic PU coating Type de document : texte imprimé Auteurs : Qian Wang, Auteur ; Hang Xu, Auteur ; ShengZhong Zhou, Auteur ; Sébastien Garnier, Auteur ; Stefan Füldner, Auteur ; Lin Ye, Auteur ; Zengguo Feng, Auteur Année de publication : 2017 Article en page(s) : p. 1279-1288 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Diisocyanate d'hexaméthylène Diisocyanate de toluène Le diisocyanate de toluène (TDI : Toluene diisocyanate) est un composé organique, toxique et allergène, appartenant au groupe des isocyanates. C'est l'un des monomères de départ utilisés pour la production de polyuréthane par polymérisation. Le TDI peut réagir avec un polyol ce qui permet de former une structure uréthane. Le TDI est produit industriellement en faisant réagir du diaminotoluène (en fait un mélange de 2,4-diaminotoluène et de 2,6-diaminotoluène dans un ratio 80:20) avec du phosgène (COCl2), ce qui conduit au TDI avec une production secondaire de chlorure d'hydrogène HCl. Il sert à fabriquer des mousses expansées, molles, semi-rigides ou rigides de polyuréthane, des adhésifs, peintures, enduits souples, élastomères, etc. Elasticité Oligomères Polymères -- Synthèse Polyuréthanes Revêtements Index. décimale : 667.9 Revêtements et enduits Résumé : The hybrid cyclic isocyanate trimer with appropriate functionality and good solvent tolerance which can be used as a building block to construct polyurethane (PU) coatings was prepared by cyclo-oligomerization of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI). Among all the tested catalysts, the self-made catalyst 3-(trimethylammonio)propyl carbonate (Cat. 4) was found to possess enough catalytic efficiency to confirm the NCO conversion to reach about 50% with both high (1 wt%) and low (0.25 wt%) catalyst loading at low temperature (40°C). The IR and NMR results proved the formation of a hybrid trimer, while HPLC results showed hybrid TDI/HDI trimer predominated in the product and only trace amounts of TDI monomer (<0.5 wt%) and oligomer with higher degree of polymerization (DP) remained. Furthermore, the formed hybrid oligomer exhibited excellent solvent tolerance to benzene, chlorinated, and acetate solvents. Consequently, Cat. 4 was demonstrated to be a suitable catalyst for cyclo-oligomerization since it not only possessed enough catalytic efficiency at low temperature but also hardly resulted in higher DP oligomer. Furthermore, the curing process with PTHF-r-PEO polyol was conducted as a pilot experiment to form PU coatings at room temperature. The disappearance of NCO group in IR spectrum as well as higher storage modulus against loss modulus implied the successful curing process. The strain–stress test showed the high tensile strength of formed PU coating, whereas the rheological test and dynamic mechanical analyzer proved the formed PU coating was a typical elastic material with good crosslink structure. These results indicate the promising potential of formed PU made from hybrid TDI/HDI trimer for coating applications. Note de contenu : - EXPERIMENTAL : Materials and measurement - Synthesis of TDI/HDI hybrid trimer - Synthesis of polyurethane with TDI/HDI oligomers - RESULTS AND DISCUSSION : Catalytic screening - The characterization of TDI/HDI trimers - Influence of the ratio of TDI/HDI on the oligomerization - Solvent compatibility - The curing process of TDI/HDI trimer DOI : 10.1007/s11998-017-9926-5 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-017-9926-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29628 [article]

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