Geopolymer as a coating material : a review / Dashrath Gangaram Salvi in PAINTINDIA, Vol. LXVIII, N° 11 (11/2018)  

[article]  inPAINTINDIA > Vol. LXVIII, N° 11 (11/2018) . - p. 53-70 Titre : Geopolymer as a coating material : a review Type de document : texte imprimé Auteurs : Dashrath Gangaram Salvi, Auteur Année de publication : 2018 Article en page(s) : p. 53-70 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cendres volantes Géopolymères Les géopolymères sont la réciproque des polymères organiques. À la place de dérivés du pétrole et de la chaîne carbonée, on utilise de la matière minérale composée de silice et d’alumine. Les géopolymères sont basés sur des alumino-silicates désignés sous le terme poly(sialate), qui est une abréviation de poly(silico-oxo-aluminate) ou (-Si-O-Al-O-)n (soit n le degré de polymérisation). La structure chimique de la Figure 1 montre un géopolymère poly(sialate-siloxo) résultant d'une géosynthèse de poly(silisique) acide (SiO2)n et de potassium alumino-silicate, en milieu alcalin (KOH, NaOH). Dans cette structure, le groupement sialate (Si-O-Al-O-) est un agent de réticulation. On pense que le mécanisme de la synthèse géochimique se fait par l'intermédiaire d'oligomères (dimère, trimère) qui constituent les véritables groupements structuraux unitaires formant une structure macromoléculaire tridimensionnelle. Kaolin Liants Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : A world towards the concept of sustainable development and environment with low greenhouse gas missions, zero waste and low energy consumption is an important endeavor. Advantages associated with this material include thermal stability, acid resistance, compact structure, low density and abiIity to encapsulate hazardous wastes. Although, most of the research is focused in the field of construction industry, there is other utilization of this material. Catalysis, coating, encapsulation of hazardous waste and separation are some of the other applications. Geopolymer is an aluminosilicate materials created by dissolving it in highly alkaline solution and then transform into tridimensional tecto-aluminosilicate materials. As an inorganic material, geopolymer has a potential in fire resistant and protective coating for different surfaces including metal and concrete due to their superior mechanical, chemical and thermal resistance properties. With an additional engineering design, in curing and sintering temperature, Si:Al ratio as well as additives used wiII improve the geopolymer coating properties. The present paper outlines briefly the potential of geopolymer as a coating material to bring the world towards a better future with a reduced carbon footprint. Note de contenu : - Classification of geopolymers - Raw materials of geopolymers - Activating solutions - Commercial applications of geopolymer : Geopolymer resins and binders - Geopolymer cements and concretes - Arts and archaeology - Geopolymer materials - Geopolymer synthesis : Covalent bonding - Geopolymerization starts with oligomers - Testing - Properties of geopolymer coating - Fig. 1 : Dehydroxylation of poly(sialate-siloxo) into 3D-framework - Fig. 2 : Classification of geopolymer - Fig. 3 : Geopolymer oligomer molecules - Fig. 4 : Polycondensation into Na-poly(sialate-disiloxo) - Fig. 5 : Geopolymer oligomer molecules - Fig. 6 : External coating - Fig. 7 : External coating - Fig. 8 : Internal coating - Table 1 : An overview of various raw materials used for geopolymer synthesis - Table 2 : Alkaline activators used in geopolymerization En ligne : https://drive.google.com/file/d/1qfwjj_lg6FXyU4on6asaKLestblXWj8L/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31425 [article]

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Thermochromism technology in paint : A review / Dashrath Gangaram Salvi in PAINTINDIA, Vol. LXXI, N° 7 (07/2021)  

[article]  inPAINTINDIA > Vol. LXXI, N° 7 (07/2021) . - p. 70-78 Titre : Thermochromism technology in paint : A review Type de document : texte imprimé Auteurs : Dashrath Gangaram Salvi, Auteur Année de publication : 2021 Article en page(s) : p. 70-78 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Pigments Revêtements:Peinture Thermochromie Index. décimale : 667.6 Peintures Résumé : Thermochromism is the property of substances to change color due to a change in temperature. A mood ring is an excellent example of this phenomenon, but thermochromism also has more practical uses, such as baby bottles which change to a different color when cool enough to drink, or kettles which change when water is at or near boiling point. Thermochromism is one of several types of ch romism Thermochromic pigments are sensitive to temperature. They change colour when they are heated up or cooled down. This property is useful for indicating if the drink in a cup is hot, or if the water in a kettle is hot. Phosphorescent pigments glow in the dark. They are able to absorb light energy and store it. Thermochromic paints use liquid crystals or leuco dye technology. After absorbing a certain amount of light or heat, the crystallic or molecular structure of the pigment reversibly changes in such a way that it absorbs and emits light at a different wavelength than at lowertemperatures. A mood ring shown face front, showing a band of green color change across a brown background. Note de contenu : - ORGANIC MATERIALS : Thermochromatic liquid crystals - Leuco dyes - How thermochromic liquid crystals work - How leucodyes work - Polymers - Thermochromic polymer systems based on bragg reflection - Liquid crystalline polymers with thermochromic properties - Thermochromic gel networks based on bragg reflection - Thermochromic polymer systems based on the absorption of light conjugated polymers - Gel networks - Inorganic thermochromic material - Irreversible inorganic thermochromes - Application of thermochromic technology - Table 1 : Generic types of thermochromic polymers classified by the effect on light - Fig. 1 : Molecular structure of the acrylates C6M and CBC - Fig. 2 : Thermochromic switching from blue to colorless of a thermoplastic polymer foil - Fig. 4 : Proton-transfer equilibrium between the phenol and phenolate form of the indicator dye 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridino)-phenol - Fig. 5 : Thermochromic switching of a 3-mm-thick Cresol Red containing PVA/borax/surfactanthydrogel layer placed between two glass plates - Fig. 6 : Visible absorption spectra of a 2,6-dipheny1-4-(2,4,6-tripheny1-1-pyridino)-phenolate containing PVA/borax/surfactant hydrogel in dependence on temperature (d = 1 cm). 100C (A); 20.0 (B); 30°C (C); 40.0 (D); 50.0 (E); 60.0 (F); 700C (G); 800C (H) - Fig. 7 : UV-vis absorption spectra of a Cresol Red containing PVA/borax/surfactant hydrogel in dependence on temperature (d = 1 cm). 160C (A); 600C (B); 80.0 - Fig. 14 : Switching behavior of a sun protecting glazing (100 x 50 cm) containing a 2-mm-thick thermotropic hydrogel layer at 20.0 slightly above the switching temperature of 30.0 En ligne : https://drive.google.com/file/d/1XPp0wItymGTheYsoucbfVO5Wy_fINow7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36309 [article]

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