D₂-m-Carborane-Siloxanes. VI. Oxidative Stabilization of Vulcanizates with Ferric Oxide

Abstract

Ferric oxide produced from iron pentacarbonyl was evaluated as an oxidative stabilizer in D2-m-carborane-siloxane and polydimethylsiloxane vulcanizates. The results indicate a significant improvement in efficiency compared to powdered ferric oxide. Thus a carborane-siloxane vulcanizate retained elastomeric properties after 1000 hours in air at 315°C. The practical upper use temperature for carborane-siloxane vulcanizates were evaluated by heat aging samples at 340° and 370°C.

The development of carborane-siloxane polymers

“…A vulcanízate containing 30 phr trimethylsilated silica and 0.25 phr finely dispersed ferric oxide exhibited good retention of mechanical properties after heat aging in air at 315 °C for up to 1000 h (Peters et al, 1978). The data in Table IV show that there is a gradual decrease in elongation along with a gradual increase in modulus.…”

D2-m-Carborane Siloxanes. 7. Synthesis and Properties of Ultra-High Molecular Weight Polymer

“…Recently we described the synthesis of linear, high molecular weight £)2-m-carborane siloxanes based on the condensation reaction between bis(ureido)silanes and carborane disilanolU3 These polymers have unusual thermal stability and have potential utility as high-temperature elastomers. 1,4,5 In previous work, polymers with molecular weights up to 250 000 were prepared.1-3 Within the range of 50 000 to 250000, an increase in the molecular weight of the polymer resulted in improvements in the mechanical properties for both polymer and vulcanízales. 4 Similar improvements in properties with increasing molecular weight were noted for poly(dimethylsiloxane).6 Thus, a rapid improvement in the tensile strength was noted for poly(dimethylsiloxane) with increasing molecular weight up to 500 000.…”