Ambient temperature and UV-cured hybrid coatings from acetoacetylated non-isocyanate polyurethanes / H. R. Asemani in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 2 (03/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 2 (03/2021) . - p. 469-488 Titre : Ambient temperature and UV-cured hybrid coatings from acetoacetylated non-isocyanate polyurethanes Type de document : texte imprimé Auteurs : H. R. Asemani, Auteur ; V. Mannari, Auteur Année de publication : 2021 Article en page(s) : p. 469-488 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Acétoacétate Caractérisation Essais (technologie) Matériaux hybrides Michael, Addition de L'addition de Michael ou réaction de Michael est une réaction qui permet la création de liaisons carbone-carbone, voire de liaisons carbone-soufre. Il s'agit de l'addition nucléophile d'un carbanion sur un composé carbonylé α,β insaturé (aldéhyde, cétone et même ester α,β insaturé, des nitriles et des amides α,β insaturés pouvant aussi être utilisés). Elle appartient à la famille des additions nucléophiles conjuguées. Cette réaction doit son nom au chimiste américain Arthur Michael. Oligomères Photoréticulation Polymères -- Synthèse Revêtements -- Séchage sous rayonnement ultraviolet Revêtements organiques Revêtements sans isocyanates Rhéologie Index. décimale : 667.9 Revêtements et enduits Résumé : Preparation of ambient and UV curing non-isocyanate polyurethane (NIPU) coatings has been reported using a series of acetoacetylated non-isocyanate polyurethane (AA-NI-PUPO) oligomers. Synthesized oligomers were characterized using various techniques such as Fourier transform infrared and nuclear magnetic resonance spectroscopy. AA-NI-PUPOs showed significantly lower viscosity compared to their non-acetoacetylated counterparts. Ambient temperature-cured systems were formulated by mixing AA-NI-PUPOs and different primary amine compounds in stoichiometric proportions. Michael addition reaction of acrylates and AA-NI-PUPOs was initiated by UV curing using a photobase generator as the catalyst. NIPU coatings were studied for various thermo-mechanical properties and corrosion resistance. The selected UV-cured and ambient-cured samples showed instant and 1-h tack-free time, respectively. Results revealed that with proper selection of acetoacetylated resin and crosslinker type, coatings with properties comparable to conventional PU coatings could be formulated. Moreover, UV-curable coatings with up to 90 wt% solid could be formulated using conventional monomeric acrylates as a reactive diluent. The study demonstrates the feasibility of formulating solvent-free rapid ambient curing non-isocyanate polyurethane coatings. Note de contenu : - MATERIALS AND METHODS : Materials - Synthesis of oligomers - Preparation of coating compositions - Test methods - RESULTS AND DISCUSSION : Characterization of AA-NI-PUPOs - Viscosity measurements - Curing characterization of UV-NIPUs - Cured-film properties - Table 1 : List of acronyms used to identify oligomers and coating systems - Table 2 : Characteristics of different resins used in this study (Mn: number average molecular weight, AA : acetoacetate) - Table 3 : Screening results for A-NIPU coating samples - Table 4 : Screening results for UV-NIPU coating samples - Table 5 : Extended coating properties for selected A-NIPU coating samples - Table 6 : Extended coating properties for selected UV-NIPU coating samples - Table 7 : Tg, Td5% and Td50% values obtained from DSC and TGA analyses for selected NIPU coating samples DOI : https://doi.org/10.1007/s11998-020-00425-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-020-00425-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35608 [article]

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Dual-curable coatings obtained from multi-functional non-isocyanate polyurethane oligomers / H. R. Asemani in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 19, N° 5 (09/2022)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 19, N° 5 (09/2022) . - p. 1393-1407 Titre : Dual-curable coatings obtained from multi-functional non-isocyanate polyurethane oligomers Type de document : texte imprimé Auteurs : H. R. Asemani, Auteur ; V. Mannari, Auteur Année de publication : 2022 Article en page(s) : p. 1393-1407 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Décomposition (chimie) Dureté (matériaux) Impédancemétrie Matériaux -- Propriétés fonctionnelles Oligomères Poids moléculaires Polyuréthanes Réticulation à l'humidité Revêtements -- Propriétés mécaniques Revêtements organiques Revêtements sans isocyanates Temps de séchage Index. décimale : 667.9 Revêtements et enduits Résumé : The growing concerns and impending regulations on the usage of monomeric isocyanates in the production of polyurethane resins have led to the introduction of alternative non-isocyanate polyurethane (NIPU) systems. Although two-component NIPU coatings based on the reaction of cyclic carbonates and aliphatic amines have emerged as a promising option, they are still associated with two significant drawbacks: lower crosslinking densities due to reduced functionality of the oligomers and low ambient-temperature reactivity. This study reports the utilization of a hybrid approach to address these drawbacks. Amine-functional NIPU oligomers (NI-PUPA) were synthesized by the reaction of cycloaliphatic amine functional compounds and multi-functional cyclic carbonates in an excess amine molar ratio. After mixing the NI-PUPAs with (3-glycidyloxypropyl) trimethoxysilane (GPTMS), a dual-curable coating could be achieved by ambient curing of amines and epoxies and moisture curing of alkoxy silanes. A comparative experimental design was implemented to evaluate the effect of an additional curing mechanism. The results revealed that the additional moisture curing led to faster ambient curing, faster development of properties, enhanced flexibility even at higher crosslinking densities, and better corrosion resistance. Such advancement could facilitate the future implementation of NIPUs in high-performance ambient-curing coating applications. Note de contenu : - EXPERIMENTAL : Materials - Methods - Testing, characterization, and evaluation - RESULTS AND DISCUSSION : Characterization of NI-PUPAs - Curing characterization - Cured film properties - Table 1 : Molecular weights obtained from GPC analysis in comparison with theoretical values and the values obtained by amine value titration Table 2 : The tack-free and through-dry times of NIPU coatings based on ASTM D5898 standard - Table 3 :Konig pendulum hardness development for NIPU coatings over 7 days of curing time (method: ASTM D4366; unit: number of oscillations) - Table 4 :MEK double-rub development for NIPU coatings over 7 days of curing time - Table 5 :Properties of NIPU coatings after 7 days of curing at ambient conditions - Table 6 :Impedance at low frequencies and pore resistance values obtained from EIS analysis - Table 7 : Decomposition temperatures and residual wt.% obtained by the analysis of TGA thermograms DOI : https://doi.org/10.1007/s11998-022-00614-0 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-022-00614-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38278 [article]

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