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Toward high glass-transition temperatures in epoxy powder coatings based on BTDA / Vinay Mishra in COATINGS TECH, Vol. 20, N° 4 (07-08/2023)  

[article]  inCOATINGS TECH > Vol. 20, N° 4 (07-08/2023) . - p. 28-35 Titre : Toward high glass-transition temperatures in epoxy powder coatings based on BTDA Type de document : document électronique Auteurs : Vinay Mishra, Auteur ; Kevin M. Biller, Auteur ; Jeff Dimmit, Auteur ; Nikola Bilic, Auteur Année de publication : 2023 Article en page(s) : p. 28-35 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Benzophenone tetracarboxylic dianhydride Caractérisation Epoxydes Formulation (Génie chimique) Revêtements poudre Transition vitreuse Index. décimale : 667.9 Revêtements et enduits Résumé : Epoxy-based products are used in many applications that face aggressive operating environments. Some examples (Figure 1) are electrically insulative encapsulants or powder coatings (e.g., inside electrical motors), chemical-resistant pipe linings, adhesives, and composite parts. Under extreme service conditions (e.g., regarding heat, chemical exposure, and mechanical stresses, often in combination), many traditional epoxy formulations fail because they suffer from a loss of integrity over time. Traditional solutions require switching from epoxy to alternate chemistries such as cyanate ester, bismaleimide, and polyimides, which, while suitable, can add complexity to the process and increase cost. Aromatic dianhydrides such as BTDA® (3,3’,4,4’-benzophenone tetracarboxylic dianhydride) have been known to impart high crosslinking densities to epoxy formulations. 1,2 See details on this molecule in Table 1 and its chemical structure in Figure 2. The resulting dense crosslinking, in combination with the structure of the BTDA linkages, leads to epoxy powder coatings with high glass-transition temperatures (Tg) and heat resistance. These formulations also offer superior dielectric properties, mechanical properties, and chemical resistance. As a result, BTDA-based powder coatings find uses in aggressive environments such as those that are high temperature, involve chemical exposure, or are for long-term electrical applications. It is noteworthy that such successes are achieved using simple, bisphenol-A based solid epoxy resins (Figure 2). Specialized resins such as epoxy novolacs and other multifunctional resins can certainly raise the performance but are not necessary when using a dianhydride curing agent. Note de contenu : - A Note on proper stoichiometric treatment of dianhydride-epoxy formulations - Example applications - A technical exploration of BTDA based epoxy powder coatings : Materials and Processing - Characterization - Results and discussion - Table 1 : Chemical and Physical Characteristics of Jayhawk BTDA - Table 2 : Suggested ranges for anhydride/epoxide equivalent ratio (A/E Ratio) for BTDA-cured epoxy formulations, based on resin epoxy equivalent weight (EEW) - Table 3 : Formulation matrix and raw materials - Table 4 : Qualitative summary of performance vs formulation and process variables En ligne : https://drive.google.com/file/d/1Esf6ARsD0rjmGUR3z3dPd91ujAOq36iv/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39847 [article]

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Uncovering a critical missing piece of the coatings durability equation / Mike Diebold in COATINGS TECH, Vol. 20, N° 4 (07-08/2023)  

[article]  inCOATINGS TECH > Vol. 20, N° 4 (07-08/2023) . - p. 36-41 Titre : Uncovering a critical missing piece of the coatings durability equation : How formulators can maximize paint durability by better understanding the effects of TiO2 dispersion and photoactivity Type de document : document électronique Auteurs : Mike Diebold, Auteur ; Grant C. Breier, Auteur Année de publication : 2023 Article en page(s) : p. 36-41 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Dioxyde de titane Dispersions et suspensions Durée de vie (Ingénierie) Formulation (Génie chimique) Index. décimale : 667.9 Revêtements et enduits Résumé : Maximizing a coating's durability is a complex equation that must account for multiple factors. Making matters even more challenging is the fact that formulators have been missing a critical piece of information about how titanium dioxide (TiO2) can influence durability-until now. Today’s paint producers and formulators are under heightened pressure to create highly durable coatings for exterior architectural and industrial applications capable of standing up against harsh UV rays, rising temperatures, and severe weather events. At the same time, many applications also demand greater efficiency via longer-lasting coatings that increase the length of service before recoating and reduce material and labor costs. TiO2, a critical component of high-quality, highly protective coatings, is known to have several effects on paint durability that formulators must consider. As a strong UV light absorber, TiO2 protects underlying resin from direct interactions with the UV component of sunlight. however, TiO2 can convert some of the UV light energy into chemical energy in the form of radicals, which can then attack the binder or react with other molecules at the surface that can lead to further paint degradation. In addition to the inherent photoactivity of the TiO2 pigment, the degree of TiO2 dispersion also plays an important role in determining a paint’s durability. It is logical for formulators to assume that by decreasing the photoactivity they can create a more durable coating. However, a more nuanced approach shows that TiO2 grade can affect paint durability beyond simple TiO2 photoactivity. Note de contenu : - Closing a crucial information gap - Unexpected results - Arming formulators with value-adding information - Table 1 : Standard architectural paint formula En ligne : https://drive.google.com/file/d/1KsFcRlOn9RPre5Gt8ZsIw2HpkaiTVf45/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39848 [article]

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Documents numériques

Coatings Tech Vol. 20, N° 4 URL