Heat-Resistant Polyorganosiloxane Dielectrics

• Published in: Russian journal of applied chemistry 2022-08, Vol.95 (8), p.1169-1173
• Main Authors: Kostyleva, E. I., Novikov, A. N., Ilyina, T. A., Dedov, N. A., Shchukina, I. A.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Composite Materials; Coordination numbers; Dielectric properties; Free radicals; Heat resistance; Heat stabilizers; Heat treatment; High temperature; Hydrosilylation; Industrial Chemistry/Chemical Engineering; Infrared spectroscopy; Liquids; Macromolecules; Mineral oils; Oxidation resistance; Polydimethylsiloxane; Reaction products; Rubber; Sealants; Stabilizers (agents); Synthesis; Thermal resistance; Titanium; Zirconium
• ISSN: 1070-4272; 1608-3296
• DOI: 10.1134/S1070427222080122

New metalloorganosiloxanes (MOSs) were prepared by hydrosilylation of Ti(IV), Zr(IV), Hf(IV), and V(IV) acetylacetonates with α,ω-dihydrooligodimethylsiloxane. The reaction products were studied by DTGA and IR spectroscopy. The effect of the metallosiloxanes obtained on the heat resistance of composites based on low-molecular-mass polydimethylsiloxane rubber (SKTN) containing various types of reinforcing fillers was examined. Introduction of MOSs in an amount of 7 × 10 –3 g/(kg blend) increases the gelation onset time of the SKTN-based compound from 5 to 54 h at 250°С. In addition, the resistance of the silicone vulcanizates to thermal oxidative degradation is enhanced, and the vulcanized rubber samples preserve satisfactory physicomechanical characteristics after prolonged heat treatment. The organosilicon liquids modified with the synthesized thermal stabilizers exhibit high levels of dielectric characteristics and heat resistance in the temperature interval from 25 to 270°С. The synthesized MOSs are soluble in polyorganosiloxanes, which allows uniform distribution of small amounts of the modifier in the polymer. The presence of metals with high coordination number in the thermal stabilizer macromolecules allows efficient inactivation of free radicals in a wide temperature interval. The filled silicone vulcanizates obtained can be used as heat-resistant cable insulation and high-temperature sealants, and MOS-modified organosilicon liquids can be used as analogs of mineral oils for power transformers.