Factors influencing the emulsion polymerization of clay-platelet-assisted styrene–acrylic copolymer latexes / Chandrashekara R. Haramagatti in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 5 (09/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 5 (09/2021) . - p. 1345-1352 Titre : Factors influencing the emulsion polymerization of clay-platelet-assisted styrene–acrylic copolymer latexes Type de document : texte imprimé Auteurs : Chandrashekara R. Haramagatti, Auteur ; Amol T. Naikwadi, Auteur Année de publication : 2021 Article en page(s) : p. 1345-1352 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Argile Caractérisation Copolymère styrène acrylique Emulsions Emulsions -- Stabilité Emulsions pickering Polymérisation en émulsion Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : Controlling the particle size of solid-particle-stabilized emulsion polymers is a challenge for coating applications where high-solid-content emulsion polymers are required. Clay-particle-stabilized styrene–acrylic copolymer emulsion was prepared by a seeded semibatch emulsion polymerization process. The effect of the concentrations of clay, peptizing agent, and methacrylic acid on the processing, final particle size, and coagulum of the emulsion polymer was studied. Dynamic light scattering (DLS), dynamic mechanical analysis, differential scanning calorimetry, and field-emission-gun scanning electron microscopy techniques were employed to characterize the emulsion polymers. The kinetics of polymerization were monitored based on the percentage solid conversion, and particle size (DLS) analysis suggested a homogeneous coagulative mechanism. The zeta potential of the polymer particles indicated good stability of the emulsion. A stable, coagulum-free, low particle size (~ 300 nm) emulsion was prepared using clay platelets, and the polymer film exhibited improved thermal and mechanical properties that will make this type of emulsion polymer of great use for coating applications. Note de contenu : - Polymerization Process - Characterization : Particle size and zeta potential - Nonvolatile material (NVM) - Electrolytic stability - Freeze–thaw stability - Viscosity - Field-emission-gun scanning electron microscopy (FEGSEM) - Dynamic mechanical analysis (DMA) - Differential scanning calorimetry (DSC) - Table 1 : Effect of KTPP content on the amount of coagulum and final particle size of the emulsions - Table 2 : The effect of the clay particle concentration on the coagulum and final particle size of the emulsion polymer - Table 3 : Effect of amount of seed on final particle size and coagulum with constant amount of Laponite and KTPP. The standard deviation for particle size is ~ 31% - Table 4 : Summary of some properties of surfactant- and Laponite RD-stabilized latex particles. F–T, freeze–thaw stability test DOI : https://doi.org/10.1007/s11998-021-00498-6 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00498-6.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36437 [article]

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Heat reflective coatings / Rakesh Jain in PAINTINDIA, Vol. LXVIII, N° 1 (01/2018)  

[article]  inPAINTINDIA > Vol. LXVIII, N° 1 (01/2018) . - p. 68-84 Titre : Heat reflective coatings Type de document : texte imprimé Auteurs : Rakesh Jain, Auteur ; Vrushali Shinde, Auteur ; Amit Joshi, Auteur ; Chandrashekara R. Haramagatti, Auteur Année de publication : 2018 Article en page(s) : p. 68-84 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Economies d'énergie Pigments inorganiques Rayonnement infrarouge Réflectivité thermique Toiture -- Revêtements:Toiture -- Peinture Index. décimale : 667.9 Revêtements et enduits Résumé : Paints and coatings offer various advantages along with the aesthetic value to the substrates to which it is applied. Binders and pigments majorly contribute to various advantages of the coatings. Particularly, pigments contribution is obviously for color and opacity to the paint. Apart from color and opacity the properties such as particle size, shape, and chemistry determines the performance of the coatings. Pigments with exceptionally high light fastness, heat/IR reflectance properties are essential for exterior coatings. Preferably the roofs which are exposed most to the solar radiation impact on the high heat build-up, and add to the load on cooling. To overcome such issues mixed metal oxide/complex inorganic pigments are generally used in heat/IR reflective coating. These pigments with high total solar reflectance (TSR), results in reflecting the IR radiation and keep the surface or interior cooler. Thus they contribute to energy savings, sustainability, provide long life to coating as well as the buildings. This review article focusses on various aspects of the heat/IR reflective coatings, particularly decorative applications : The types of pigments, processes, mechanisms, advantages, and contribution to the sustainability are highlighted. Note de contenu : - SOLAR SPECTRUM AND HEAT BUILD UP : Total solar reflectance (TSR) - TYPES OF IR REFLECTIVE PIGMENTS : Inorganic pigments - Complex inorganic color pigments (CICPs) - MECHANISM OF COOL EFFECT - APPLICATIONS AND ADVANTAGES : Roof/roof tile - Military - Automotive - FIGURES : 1. Classification of solar passive cooling techniques for roofs - 2. Visual comparison of the cool color and conventional color. Cool colors are based on yellow : yellow 346 (chrome antimony), black : black 28 (copper chromite), brown 1 : brown 157 (zinc iron chromite), brown 2 : brown rosse 208 (iron oxide) - 3. A typical solar spectrum covering UV, visible and IR radiations - 4. Path of light as it penetrates two different coatings, one having pigments with a higher refractive index than the other - 5. Reflectance curves for different types of black, and the red colored curve represents non IR reflective type of black - 6. Correlation between TSR value and surface temperature for black pigments - 7. Reflectance curves for inorganic cobalt blue and organic phtalocyanine (Phtalo) blue - 8. Spectral solar reflectance of TiO2, a green leaf, standard carbon black and a complex inorganic color pigment containing infrared reflective (Fe, Cr)2O3 pigment (Normalized Solar Irradiance Shown for Reference) - 9. Principle of light falling on a surface - 10. Natural sunlight exposure in Florida shows that the CRCMs have improved the fade resistance of the painted PVDF metals - TABLE : Major suppliers, color index number, chemistry of some IR reflective pigments En ligne : https://drive.google.com/file/d/1MnQXxwnefNB6XO_-tVvTYp06z5pMZ9Ri/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30324 [article]

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Influence of concentration of redox couple on freeze-thaw stability of styrene-acrylic copolymer latex / Chandrashekara R. Haramagatti in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 13, N° 1 (01/2016)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 13, N° 1 (01/2016) . - p. 81-88 Titre : Influence of concentration of redox couple on freeze-thaw stability of styrene-acrylic copolymer latex Type de document : texte imprimé Auteurs : Chandrashekara R. Haramagatti, Auteur ; Subhadip Sikdar, Auteur ; Shruti Bhattacharya, Auteur Année de publication : 2016 Article en page(s) : p. 81-88 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Copolymère styrène acrylique Latex Oxydoréduction Polymérisation en émulsion Stabilité thermique Index. décimale : 667.9 Revêtements et enduits Résumé : Styrene-acrylic copolymer latexes were synthesized by emulsion polymerization process using sodium formaldehyde sulphoxylate (SFS) and tert-butyl hydroperoxide (TBHP) as redox initiators. Approximately 100% conversion was achieved successfully at 50°C. The redox polymerization was carried out at varied dosages of redox concentration; the lowest dosage of 0.3% was sufficient to achieve ~100% conversion. The molecular weight of the polymer was decreased with an increase in redox concentration as expected. The properties such as viscosity, specific conductivity, particle size, molecular weight, and Tg (by differential scanning calorimetric and dynamic mechanical analysis) of the redox polymers are reported. The other important property of the latexes is their freeze–thaw (F–T) stability. Even though ~100% conversion was achieved at 0.3% redox initiator couple, it failed in F–T stability test. Latexes prepared above 0.5% redox initiator couple successfully pass the five F–T cycles. The effect of sulfate from SFS, and tertiary butyl from TBHP species on the stability of the latexes is discussed. The F–T stability of the emulsions is very crucial in the coatings industry, and this article brings some insight into the effect of concentration of redox species on the stability of emulsions. Moreover, low-temperature processes are always appreciated in terms of safety and energy savings. DOI : 10.1007/s11998-015-9727-7 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-015-9727-7.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25378 [article]

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