[article]
| Titre : |
SILICON : Past, present and future in paint industry |
| Type de document : |
texte imprimé |
| Auteurs : |
Amruta Vinod Joshi, Auteur |
| Année de publication : |
2007 |
| Article en page(s) : |
p. 151-168 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Revêtements
SiliconesLes silicones, ou polysiloxanes, sont des composés inorganiques formés d'une chaine silicium-oxygène (...-Si-O-Si-O-Si-O-...) sur laquelle des groupes se fixent, sur les atomes de silicium. Certains groupes organiques peuvent être utilisés pour relier entre elles plusieurs de ces chaines (...-Si-O-...). Le type le plus courant est le poly(diméthylsiloxane) linéaire ou PDMS. Le second groupe en importance de matériaux en silicone est celui des résines de silicone, formées par des oligosiloxanes ramifiés ou en forme de cage (wiki).
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| Index. décimale : |
667.6 Peintures |
| Résumé : |
The present paint industry is dominated by carbon chemistry. Silicon is a tetravalent element like carbon. Structurally, both the elements resemble each other, and both form chains made up of repeating units - an essential prerequisite, a polymer chemist is looking for. Inorganic and organic silicon based compounds exhibit extraordinary properties and find wide application in paint industry. Few of the important applications are listed below : • Inorganic zinc silicate primers • Silicone resins for high temperature resistance • Silicone modified resins for coil coatings • Water proofing of concrete structures by impregnation • Molecular sieves as moisture scavengers • Additives as adhesion promoters, defoamers, slip agents etc. The paper discusses these applications along with the underlying basic chemistry of silicon. Though, carbon and silicon, both are tetravalent elements, the three principal characteristics of silicon that distinguish it over carbon, are: 1. Silicon has tremendous affinity for oxygen, and is difficult to separate from oxygen. Thus silicon-oxygen bond is much stable than carbon-oxygen or carbon-carbon bond. 2. Silicon is active at very high temperatures but sluggish in its reactions at room temperature i.e. it has a high activation energy. 3. The covalent compounds of silicon, such as hydrides and halides, are not stable towards air and water, unlike similar carbon compounds. 4. Silicon has d - orbitals readily available in its atomic structure, and so it can expand its bonding capacity to six instead of being limited to four, in case of carbon. |
| Note de contenu : |
How much silicon and why ? - Structure of the silicates
I - Orthosilicates
II - Pyrosilicates
III - Cyclic silicates
IV - Chain silicates
V - Sheet silicates
VI - Three-dimensional silicates
Silicon a late bloomer
- Applications : 1. Water repellant coating - 2. Zinc silicate - 3. Protection of construction materials - 4. N-Halamine siloxane as a biocide - 5. Silanes as adhesion promoter - 6. Silicone polyesters
- Uses of silicone co-polymer coatings : 7. Fiber glass reinforced thermosetting resins - 8. Fumed silica - 9. Silicone additives |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11452 |
in PAINTINDIA > Vol. LVII, N° 5 Suppl. (05/2007) . - p. 151-168
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