Anticorrosive barrier coatings modified by core-shell rubber particles : effects on the property transients and premature crack initiation susceptibility of particle type and concentration / Qiong Li in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 21, N° 3 (05/2024)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 21, N° 3 (05/2024) . - p. 1145-1162 Titre : Anticorrosive barrier coatings modified by core-shell rubber particles : effects on the property transients and premature crack initiation susceptibility of particle type and concentration Type de document : texte imprimé Auteurs : Qiong Li, Auteur ; Søren Kiil, Auteur Année de publication : 2024 Article en page(s) : p. 1145-1162 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Anticorrosifs Anticorrosion Caoutchouc Caractérisation Core-Shell Epoxydes Matériaux -- Propriétés barrières Particules (matières) Revêtement en phase solvant Revêtements organiques Titanate de strontium Index. décimale : 667.9 Revêtements et enduits Résumé : Protective epoxy coatings, as a result of their inherent brittleness, show insufficient resistance towards initiation and propagation of cracks, which can occur as early as during the curing process. To improve premature crack initiation resistance, it is essential to understand the underlying mechanisms. In this work, a solvent-based novolac epoxy, cured with a cycloaliphatic amine, was reinforced with either an epoxypropoxypropyl-terminated polydimethylsiloxane (PDMS), nanoparticles of strontium titanate (SrTiO3), or core-shell rubber (CSR) nanoparticles. The effects on coating property transients, curing-induced internal stress, and premature crack initiation susceptibility of the modifier types and CSR (MX 217 and MX 267) concentrations were investigated. In addition, using a digital microscope, the defect and crack morphology in coatings applied to rigid, flat substrates and inner 90-degree angles were characterized. Finally, to evaluate the anticorrosive barrier performance of the reinforced coatings, an electrochemical impedance spectroscopy analysis was employed. Despite a slightly reduced crack initiation susceptibility, the flexible PDMS chains, due to phase separation, resulted in a deteriorated barrier performance. The inclusion of SrTiO3 nanoparticles also led to a reduced anticorrosion performance, relative to a neat epoxy coating, with a slightly lower crack initiation susceptibility and a minor increase (around 0.2 MPa) in the average internal stress. For 5 wt% MX 217 and MX 267 CSR toughened coatings, the maximum internal stress and crack initiation susceptibility in the series, as well as an associated reduced corrosion resistance, were seen. In spite of a reduction in the elastic modulus, an improved barrier performance and a reduced internal stress and crack initiation susceptibility were observed for 25 wt% MX 217 and 37 wt% MX 267 CSR toughened coatings. To improve barrier properties and avoid premature crack initiation of epoxy coatings, guidelines on modifier selection are provided. Note de contenu : - EXPERIMENTAL : Materials and coating preparation - Characterizations - RESULTS AND DISCUSSION : Effect of modifier type - Effects of CSR concentrations - Effects of modifiers on coating barrier properties DOI : https://doi.org/10.1007/s11998-023-00885-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-023-00885-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=41083 [article]

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Parallel measurements and engineering simulations of conversion, shear modulus, and internal stress during ambient curing of a two-component epoxy coating / Qiong Li 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; 1331-1343 Titre : Parallel measurements and engineering simulations of conversion, shear modulus, and internal stress during ambient curing of a two-component epoxy coating Type de document : texte imprimé Auteurs : Qiong Li, Auteur ; Claus Erik Weinell, Auteur ; Søren Kiil, Auteur Année de publication : 2022 Article en page(s) : P; 1331-1343 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse thermomécanique dynamique Cinétique chimique Dynamique Epoxydes Modèles mathématiques Réticulation (polymérisation) Revêtements bi-composant Revêtements organiques Rhéologie Taux de retrait Thermodurcissables Index. décimale : 667.9 Revêtements et enduits Résumé : Macroscopic crack initiation and propagation, as a result of internal stress, poses a threat to the performance of protective coatings. In demanding environments, such as corner geometries and saltwater exposure, the cracks may accelerate substrate corrosion and potentially lead to collapse of infrastructure. The present work is focused on the underlying mechanisms of curing-induced internal stress and investigates the dynamics of the parallel processes of crosslinking reactions and evolution of mechanical properties for a solvent and pigment-free epoxy resin cured with a diamine hardener. Experimental techniques, applied at room temperature and constant relative humidity, include attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, advanced rheometry, dynamic mechanical thermal analysis (DMTA), and a beam deflection device. When taking post-vitrification mobility control into account, the reaction kinetics behind the crosslinking and network development could be simulated with a modified Kamal–Sourour model. In addition, engineering models for simulation of coating modulus, volumetric shrinkage, and internal stress as a function of conversion were proposed and found to be in good agreement with experimental data. This allowed, by comparing the magnitudes of the modulus and the internal stress, for evaluation of whether premature cracks are expected to initiate. Furthermore, we show that the curing-induced internal stress development is strongly influenced by the current coating elastic modulus and film thickness, highlighting the effect of coating property transients. The experimental techniques and engineering modeling tools collected can be used to evaluate, without demanding computational complexities, the simultaneous development of coating modulus and curing-induced internal stress. Note de contenu : - EXPERIMENTAL : Materials and coating preparation - FTIR spectroscopy - Dynamic mechanical thermal analysis (DMTA) measurements - Tensile test - Curing shrinkage measurement - Internal stress measurements - MATHEMATICAL MODELING : Curing kinetics - Chemical strain model - Elastic behavior of coating - RESULTS AND DISCUSSION : Evolution of coating properties during curing - Comparison of model simulations with experimental data DOI : https://doi.org/10.1007/s11998-022-00652-8 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-022-00652-8.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38273 [article]

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