Synthesis of a curing agent containing trifunctional epoxy groups for powder coatings and its curing reaction kinetics / Qiuping Su in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 19, N° 3 (05/2022)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 19, N° 3 (05/2022) . - p. 907-917 Titre : Synthesis of a curing agent containing trifunctional epoxy groups for powder coatings and its curing reaction kinetics Type de document : texte imprimé Auteurs : Qiuping Su, Auteur ; Zilun Tang, Auteur ; Jiajian He, Auteur ; Yuxin Gu, Auteur ; Yong Li, Auteur ; Jing Xie, Auteur ; Shaoshun Wang, Auteur ; Ruijun Lin, Auteur ; Xiaofeng Lin, Auteur ; Wenjing Lin, Auteur ; Guobin Yi, Auteur Année de publication : 2022 Article en page(s) : p. 907-917 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Cinétique chimique Composés organiques -- Synthèse Morphologie (matériaux) Polyesters Polymérisation Réticulants Revêtements organiques Revêtements poudre Stabilité thermique Index. décimale : 667.9 Revêtements et enduits Résumé : In this work, tris(oxiran-2-ylmethyl) benzene-1,3,5-tricarboxylate (TOTC) was synthesized by a new two-step method without using harmful epichlorohydrin and served as a curing agent for polyester powder coatings. The chemical structure of TOTC was determined by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The curing behavior and the curing reaction kinetics of TOTC/polyester resin (NH-3307) system were studied by dynamic differential scanning calorimetry. The activation energy Ea was 71.75 kJ mol-1 according to Flynn–Wall–Ozawa method, and the curing reaction of TOTC/NH-3307 system was described by Friedman method. It was found that the curing reaction of TOTC/NH-3307 system was a two-parameter autocatalysis which followed the Å estάk–Berggren model. The nonisothermal curing reaction rate was simulated according to the Å estάk–Berggren model and the experimentally parameters. What is more, the thermogravimetric analysis results showed that the TOTC/NH-3307 system had good thermal stability with an initial decomposition temperature of 374.92°C. The TOTC/NH-3307 cured film exhibited excellent leveling performance by SEM. The results demonstrated that TOTC has efficient curing ability and huge market potential. Note de contenu : - Experimental : Materials - Methods : Synthesis of triallyl benzene-1,3,5-tricarboxylate (TATC) - Synthesis of tris(oxiran-2-ylmethyl) benzene-1,3,5-tricarboxylate (TOTC) - Preparation of powder coatings - Characterization and instrumentation - Results and discussion : Synthesis and characterization of TOTC - Curing kinetics and mechanism analysis : Nonisothermal DSC cure - Curing kinetics - Curing mechanism - Thermal stability analysis - Surface morphology analysis - Table 1 : Characteristic parameters of TOTC/NH-3307 powder coating system - Table 2 : Characteristic peak conversion values and calculated kinetic parameters for autocatalytic model at different heating rates DOI : https://doi.org/10.1007/s11998-021-00578-7 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00578-7.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38085 [article]

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Synthesis of a novel hyperbranched polyester with carboxyl end groups applied to UV-curable waterborne coating / Jieming Liu in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 1 (01/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 1 (01/2021) . - p. 259-269 Titre : Synthesis of a novel hyperbranched polyester with carboxyl end groups applied to UV-curable waterborne coating Type de document : texte imprimé Auteurs : Jieming Liu, Auteur ; Shaoshun Wang, Auteur ; Qiuping Su, Auteur ; Jiajian He, Auteur ; Yong Li, Auteur ; Jing Xie, Auteur ; Guobin Yi, Auteur Année de publication : 2021 Article en page(s) : p. 259-269 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse mécanique dynamique Caractérisation Groupement carboxyle Hydrostabilité Polyesters Polymères -- Synthèse Polymères ramifiés Revêtements -- Propriétés mécaniques Revêtements -- Propriétés thermiques Revêtements en phase aqueuse Revêtements en phase aqueuse -- Séchage sous rayonnement ultraviolet Revêtements organiques Rhéologie Solubilité Index. décimale : 667.9 Revêtements et enduits Résumé : A hyperbranched polyester with carboxyl end group (HPC) was synthesized by using trimellitic anhydride and neopentyl glycol as raw materials via A2 + B3 polycondensation. Then, waterborne hyperbranched polyester acrylate (WHPC) was synthesized by partially modifying the carboxylic groups of HPC with glycidyl methacrylate. In order to explore the influence of molecular weight, acrylate groups content, and ion groups content on performances, a series of WHPC films with different molecular weight, acrylate groups content, and ion groups content were prepared. The dynamic light scattering spectrometer analysis shows that the higher ionic groups content and the lower molecular weight cause the smaller particle size. The ionic group content has a positive effect on the solubility. The smaller molecular weight and particle size cause the lower viscosity. The Fourier-transform IR spectrophotometer reveals that the double bond final conversion increased with increasing acrylate groups content. The final conversion is between 69 and 86%. The curing speed is fast, and the curing time is about 70 s due to the numerous end groups owned by the hyperbranched structure. The dynamic mechanical thermal analysis coupled with end-use mechanical property tests illustrates that the crosslink density has a positive effect on the storage modulus and a negative effect on the flexibility. It is also found that glass transition temperature and pencil hardness are determined by the balance between crosslink segment and hyperbranched polyester segment. The thermogravimetric analysis proves that increased crosslink density and molecular weight promote the heat resistance of films. This work utilizes a novel hyperbranched structure that excels in viscosity, flexibility, and water solubility. Furthermore, the preparation process is convenient. Note de contenu : - EXPERIMENTAL : Materials - Synthesis of hyperbranched polyester with carboxyl end groups (HPC) - Synthesis of waterborne hyperbranched polyester acrylate (WHPC) - Neutralization of the prepolymer - Dispersion formation - UV curing - Measurements - RESULTS AND DISCUSSION : Characterizations of hyperbranched polyester - Gel permeable chromatography (GPC) analysis - Particle size - Rheological behavior - Water solubility and stability - Curing kinetics and boule bond conversion - Dynamic mechanical thermal analysis (DMTA) - Thermal properties - Table 1 : Sample designation and stoichiometric ration of -COO- and GMA for the preparation of WHPC - Table 2 : The particle diameter in water and COO- groups content of WHPCs - Table 3 : Dynamic mechanical properties of the UV-cured coatings - Table 4 : The mechanical properties and performance of the UV-cured coatings - Table 5 : The degradation temperature at 5% weight loss DOI : https://doi.org/10.1007/s11998-020-00404-6 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-020-00404-6.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35368 [article]

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