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Copolymers of styrene and maleic anhydride : reactivity ratio, physical behavior and spectral properties / Suman Kumari in PAINTINDIA, Vol. LVIII, N° 11 (11/2008)
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Titre : Copolymers of styrene and maleic anhydride : reactivity ratio, physical behavior and spectral properties Type de document : texte imprimé Auteurs : Suman Kumari, Auteur ; Dhirendra Nigam, Auteur ; Devendra Agarwal, Auteur ; Indira Nigam, Auteur Année de publication : 2008 Note générale : Bibliogr. Langues : Anglais (eng) Tags : Styrene maleic anhydride (SMA) copolymer Reactivity ratio Index. décimale : 667.9 Revêtements et enduits Résumé : Radical polymerization of styrene and maleic anhydride was carried out in N,N-dimethylformamide (DMF) as a solvent at the temperature of 80°C using benzoylperoxide as initiator. The monomer ratio was varied in the range of 0.5:1 to 4:1. The copolymer compositions were determined by CHN-elemental analysis. The copolymers were characterized by CNMR spectroscopy and was used to determine the copolymer composition. These values are comparable to those obtained from CHN-analysis although the mole fractions of styrene as observed by elemental analysis in the copolymers is slightly higher than the corresponding values observed by CNMR spectra. The ratio of styrene and maleic anhydride in the copolymer was in the range of 1.02 - 1.17 up to the monomer feed ration 2:1 and increased to about 1.53 for feed ratio of 4:1. This shows styrene and maleic anhydride have a strong tendency to form an alternating copolymer which deviates slightly when higher concentration of styrene is taken in the feed. This tendency can be explained on the basis of either of two mechanisms viz. chain transfer complex formation as well as penultimate effect due to presence of a polar solvent. The reactivity ration were determined by various methods viz Myao Lewis, Fineman Ross method, Kelen Tudos methods. The more precise value of reactivity ratio could be determined by Kelen Tudos as compared to other methods. The reactivity ratios determined by these methods shows that r1r2 <<1 which further indicated that on copolymerization of styrene and maleic anhydride, an alternating copolymer was formed. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6961
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Code-barres Cote Support Localisation Section Disponibilité 011351 - Périodique Bibliothèque principale Documentaires Disponible Dimethyl secondary amine chain extenders : a conceptual approach to in situ generation of advanced epoxy resins for rapid-cure, low-VOC coatings / Frederick H. Walker in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 6, N° 3 (09/2009)
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Titre : Dimethyl secondary amine chain extenders : a conceptual approach to in situ generation of advanced epoxy resins for rapid-cure, low-VOC coatings Type de document : texte imprimé Auteurs : Frederick H. Walker, Auteur ; Rob Rasing, Auteur ; Gamini A. Vedage, Auteur ; Michael Cook, Auteur Année de publication : 2009 Article en page(s) : p. 283-313 Note générale : Bibliogr. Langues : Américain (ame) Tags : Poly(N-methylazetidine) Dimethyl-meta-xylylenediamine Pseudo-first-order kinetic Amine reactivity epoxy curing agent Epoxy resin coating Flexibility Crosslink density Miller-Macosko calculation Chain extender VOC Low temperature cure Environmental movement Electrochemical impedance Aine reaction mechanism Mannich base Index. décimale : 667.9 Revêtements et enduits Résumé : Advanced epoxy resin oligomers have traditionally been utilized for coatings that combine fast dry-to-touch speed and good flexibility--properties demanded in many markets such as marine and industrial maintenance coatings. Unfortunately, advanced epoxy resins require formulation with large quantities of solvent that make attainment of modern VOC regulations difficult or impossible. Coatings formulated from low molecular weight liquid epoxy resin, on the other hand, can easier meet VOC challenges, but dry slowly and tend to be brittle. This presentation explores the concept of using fast reacting, di-functional amine chain extenders to generate epoxy oligomers in situ as a means to meet these opposing property demands. Methylamine-terminated poly-(N-methylazetidine) (pNMAz, 1) is prepared in a two-step process involving the Michael addition of methylamine to acrylonitrile, followed by hydrogenation in a methylamine-containing atmosphere to yield an oligomer stream with an [M.sub.n] of about 250. Competitive pseudo-first-order kinetic measurements conducted in isopropyl alcohol indicate methyl-substituted disecondary diamines reacted approximately 3 to 3.6 times faster with phenyl glycidyl ether (PGE) than the primary amine meta-xylylenediamine (MXDA). These chain extenders can be formulated with traditional multi-functional amine crosslinkers to yield coatings with lower VOC, faster dry speed, and better flexibility compared to corresponding coatings formulated without the chain extender. DOI : 10.1007/s11998-009-9178-0 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-009-9178-0.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6111
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 6, N° 3 (09/2009) . - p. 283-313[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 011503 - Périodique Bibliothèque principale Documentaires Disponible