![]() ![]() Performance under persistent high UV is key to successful application of silicone-housed insulators, arresters and bushings, such as here in southern Spain.ĬLICK TO ENLARGE Testing hydrophobicity of silicone materials after exposure to climatic stresses. Silicones show only slight changes in mechanical and wetting behavior, even after extended accelerated weathering testing in climatic chambers. Even high UV and harsh weather conditions such as found in coastal regions or deserts have little impact on this resistance property. 398 kJ/mol) and can therefore cleave C-C bonds but not the Si-O bond that remains stable. Shortwave sunlight at 300 nm has an energy content of about 6.2×10 -22 kJ (i.e. For example, the bonding energy of Si-O bonds is 444 kJ/mol versus only 348 kJ/mol for C-C bonds. The high bonding energy of the silicon to oxygen (Si-O) backbone provides stability against breakdown by UV irradiation. Silicones have a structure similar to organically modified quartz. Green represents silicon atoms, blue is oxygen atoms. This edited contribution to INMR by experts at Wacker Chemie in Germany discusses how it is this chemical structure that makes silicones able to satisfy important properties required across diverse power industry applications.īall-model of polydimethylsiloxane (PDMS). V stands for the vinyl groups (R-CH=CH 2) that represent the material’s curable species. One accepted standard abbreviation for silicones is VMQ, where Q stands for rubber having silicon and oxygen in the polymer chain while M indicates that the material mainly contains methyl groups (CH 3). As such, they differ widely from hydrocarbon-based materials. Rather, they consist of repeating silicon-oxygen (siloxane) groups with two methyl groups each bonded to the silicon. In contrast to other polymeric insulation materials, silicones (also known as polydimethylsiloxanes) are not made up of a carbon to carbon backbone.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |