Characterization of immiscibly blended polyurethane coatings part 1 : selective staining for enhanced micro-Raman spectroscopy / Nicholas W. M. Heller in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 14, N° 1 (01/2017)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 14, N° 1 (01/2017) . - p. 163-175 Titre : Characterization of immiscibly blended polyurethane coatings part 1 : selective staining for enhanced micro-Raman spectroscopy Type de document : texte imprimé Auteurs : Nicholas W. M. Heller, Auteur ; Clive R. Clayton, Auteur ; Spencer L. Giles, Auteur ; James H. Wynne, Auteur ; Mark E. Walker, Auteur ; Mark J. Wytiaz, Auteur Année de publication : 2017 Article en page(s) : p. 163-175 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agent mattant Epoxydes Matériaux -- Coloration Pigments Polyacryliques Polyols Polyuréthanes Réticulation (polymérisation) Revêtements poudre:Peinture poudre Spectroscopie Raman Styrène Thermodurcissables Index. décimale : 667.9 Revêtements et enduits Résumé : Raman spectroscopy (RS) mapping of the selective infiltration of styrene monomer has been developed as a protocol for polymeric phase identification in resin-blended thermoset powder coatings. Blends of incompatible acrylic polyols, with low and high hydroxyl contents, combined with matting agents and pigments, were crosslinked to produce unique low gloss thermosets. The low reflectance originated from a synergistic effect between the polymeric phase separation and the incorporation of the matting agents and pigments. RS conclusively identified the phases within the blended film using polyester-embedded cross-section samples. Further analysis has revealed that monomeric styrene from the polyester-embedding resin produced the spectroscopic handle necessary for domain identification. Preferential infiltration of styrene was therefore investigated through dip and vapor staining of the blended and individual resin films. The spectroscopic handle had manifested through the consistent infiltration of styrene within the low hydroxyl film. The contamination in the cross-sections was eliminated when an epoxy-embedding resin was utilized, which produced no such marker peak in the ensuing spectra. These observations led to the development of the described selective staining protocol for micro-Raman analysis, which enabled very reproducible results for enhanced chemical mapping of phase-separated coatings. Note de contenu : - EXPERIMENTAL : Coating preparation - Optical microscopy - Differential scanning calorimetry (DSC) - Raman spectroscopy - Cross-section sample preparation - Styrene vapor staining - RESULTS AND DISCUSSION : DSC analysis and optical microscopy of the blend surface - Raman spectroscopy of coating surfaces and embedded cross-sections - Domain identification by Raman mapping - Controlled staining with styrene vapor DOI : 10.1007/s11998-016-9839-8 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-016-9839-8.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27798 [article]

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Silyl-containing polyurethanes that selectively disassemble with fluoride salts / Erick B. Iezzi in COATINGS TECH, Vol. 17, N° 1 (01/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 1 (01/2020) . - p. 26-32 Titre : Silyl-containing polyurethanes that selectively disassemble with fluoride salts Type de document : texte imprimé Auteurs : Erick B. Iezzi, Auteur ; Eugène Camerino, Auteur ; Grant C. Daniels, Auteur ; James H. Wynne, Auteur Année de publication : 2020 Article en page(s) : p. 26-32 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Fluorures Polymères -- Détérioration Polymères à silane modifié Polyuréthanes Revêtements -- Détérioration Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : Crosslinked networks, such as two-component polyurethanes, are used for numerous commercial applications because of their unique mechanical, thermal, and hydrocarbon resistant properties. However, the covalently bonded linkages in these materials are irreversible, which renders them difficult to degrade and destroy unless hazardous chemicals, mechanical abrasion, or thermal treatments are employed. Many of these treatments are labor-intensive, expensive, or present environmental and health concerns. To address these issues, we have developed a novel silyl-based technology that imparts degradable capabilities to crosslinked polyurethane networks, such as coatings. These silyl-containing polyurethanes are thermally stable and highly crosslinked, yet they will disassemble on demand via cascading bond cleavage when exposed to a selective, mild, and environmentally friendly fluoride salt solution. Furthermore, these polyurethanes are resistant to disassembly with strong acid and base solutions, which demonstrates their selectivity and robustness compared to other degradable crosslinked networks. Note de contenu : - Fig. 1 : Removal of the crosslinked polyurethane coating on Navy Aircraft using a methylene chloride-based paint stripper and mechanical sanders - Fig. 2 : Illustration of a brick house degrading into powder upon contact with rain droplets - Fig. 3 : Structures of silyl-centered diols, silyl-centered triol, and isocyanate crosslinkers used to form crosslinked polyurethane networks - Fig. 4 : Illustrations of silyl-containing and non-silyl-containing polyurethane networks, where the silicon atoms of the silyl-containing polyurethanes are highlighted in red and the blue expansion boxes show a close-up of network aliphatic chains and carbamate linkages - Fig. 5 : Mechanisms of disassembly with fluoride ion for silyl-containing polyurethane 8 and silyl-containing polyurethane 9, and illustration of partially disassembled network 8, where green indicates activated (i.e., cleaved) silyl groups, red indicates non-activated silyl gruops, and aliphatic amine trimers are shown as all black - Fig. 6 : Time-lapse images of polyurethane 8 immersed in THF and 1.0 MTBAF in THF for five days at room temperature. Polyurethane 8 was unaffected by the THF, yet completely disassembled within five days of exposure in the fluoride salt solution. The networks are outlined in red for visual indciation - Table 1 : Average Tg of networks after static immersion in solutions at room temperature - Table 2 : Average Tg of networks after static immersion in solutions of acetone and PM acetate En ligne : https://drive.google.com/file/d/1_QRMW7CVrk_cwMUcC3GPnL36BC0rOEuQ/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33601 [article]

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