Critical role of particle/polymer interface in photostability of nano-filled polymeric coatings / Xiaohong Gu in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 9, N° 3 (05/2012)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 9, N° 3 (05/2012) . - p. 251-267 Titre : Critical role of particle/polymer interface in photostability of nano-filled polymeric coatings Type de document : texte imprimé Auteurs : Xiaohong Gu, Auteur ; Guodong Chen, Auteur ; Minhua Zhao, Auteur ; Stephanie S. Watson, Auteur ; Tinh Nguyen, Auteur ; Joannie W. Chin, Auteur ; Jonathan W. Martin, Auteur Année de publication : 2012 Article en page(s) : p. 251-267 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Essais accélérés (technologie) Interfaces (Sciences physiques) Nanoparticules Oxyde de zinc Photodétérioration Polyuréthanes Résistance au rayonnement ultraviolet Revêtements en phase aqueuse:Peinture en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : Nanoparticle-filled polymeric coatings have attracted great interest in recent years because the incorporation of nanofillers can significantly enhance the mechanical, electrical, optical, thermal, and antimicrobial properties of coatings. Due to the small size of the fillers, the volume fraction of the nanoparticle/polymer interfacial area in nano-filled systems is drastically increased, and the interfacial region becomes important in the performance of the nano-filled system. However, techniques used for characterizing nanoparticle/polymer interfaces are limited, and thus, the mechanism by which interfacial properties affect the photostability and the long-term performance of nano-filled polymeric coatings is not well understood. In this study, the role of the nanoparticle/polymer interface on the ultraviolet (UV) stability of a nano-ZnO-filled polyurethane (PU) coating system was investigated. The effects of parameters influencing the particle/polymer interfacial properties, such as size, loading, surface modification of the nanoparticles, on photodegradation of ZnO/PU films were evaluated. The nature of the interfacial regions before and after UV exposures were characterized by atomic force microscopy (AFM)-based techniques. Results have shown that the interfacial properties strongly affect chemical, thermo-mechanical, and morphological properties of the UV-exposed ZnO/PU films. By combining tapping mode AFM and novel electric force microscopy (EFM), the particle/polymer interfacial regions have been successfully detected directly from the surface of the ZnO/PU films. Further, our results indicate that ZnO nanoparticles can function as a photocatalyst or a photostabilizer, depending on the UV exposure conditions. A hypothesis is proposed that the polymers in the vicinity of the ZnO/PU interface are preferentially degraded or protected, depending on whether ZnO nanoparticles act as a photocatalyst or a photostabilizer in the polymers. This study clearly demonstrates that the particle/polymer interface plays a critical role in the photostability of nano-filled polymeric coatings. Note de contenu : - EXPERIMENTAL : Materials and specimen preparation - High UV radiant laboratory exposure - Measurements - RESULTS AND DISCUSSION : Thermo-mechanical properties of nano-filled coatings and their relationship with interfacial interactions - Detecting embedded nanoparticle/polymer interface using AFM-based techniques - Role of nanoparticle/polymer interface in photostability of nano-filled polymeric coatings DOI : 10.1007/s11998-011-9326-1 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-011-9326-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15950 [article]

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Effect of tio2 pigment type on the uv degradation of filled coatings / Deborah L. Wang in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 8, N° 1 (01/2011)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 8, N° 1 (01/2011) . - p. 19-33 Titre : Effect of tio2 pigment type on the uv degradation of filled coatings Type de document : texte imprimé Auteurs : Deborah L. Wang, Auteur ; Stephanie S. Watson, Auteur ; Li-Piin Sung, Auteur ; I-Hsiang Tseng, Auteur ; Craig J. Bouis, Auteur ; Raymond Fernando, Auteur Année de publication : 2011 Article en page(s) : p. 19-33 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Dioxyde de titane Fourier, Spectroscopie infrarouge à transformée de Microscopie confocale à balayage laser Photodétérioration Pigments photoréactifs Polymères -- Effet du rayonnement ultraviolet Polymères -- Détérioration Revêtements -- Détérioration Index. décimale : 667.9 Revêtements et enduits Résumé : The objective of this study was to investigate the effect of the photoreactivity of titanium dioxide (TiO2) pigments on the photodegradation of polymeric coatings used in exterior applications. Two polymer matrices, an amine-cured epoxy (EP) and an acrylic urethane (AU), containing three types of TiO2 pigments, classified by different levels of photoreactivity, were studied. Specimens were exposed on an ultraviolet (UV) weathering chamber, the Simulated Photodegradation by High Energy Radiant Exposure device at the National Institute of Standards and Technology. Two exposure conditions were used: ambient, dry condition [25°C and 0% relative humidity (RH)] and high temperature, wet condition (55°C and 75% RH), which is similar to more severe outdoor exposures. The physical and chemical degradations of the filled coatings were monitored at periodic intervals using a combination of laser scanning confocal microscopy (LSCM) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Progression of degradation on the coating surfaces was characterized by LSCM in terms of changes in surface roughness and morphology, pigment agglomerate size, and the occurrence of pits or holes in the coatings. The observed physical changes were correlated to the chemical changes measured by ATR-FTIR as a function of UV exposure time. Both EP and AU systems showed less degradation in terms of surface roughness and morphological changes under the dry conditions compared to the wet exposure conditions. It was observed that both the pigment type (and hence photoreactivity) and particle dispersion strongly affected the degradation of both EP and AU systems. DOI : 10.1007/s11998-009-9216-y En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-009-9216-y.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10919 [article]

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