Study On Silicone-Rubber Based Insulation Material And Application Of POSS

Internal insulation layers with perfect performances were required for the solid rocket. In this paper, aiming to get a high-quality silicone-rubber based ablator, basic foruma of the ablator was ascertained by orthogonal design experiment, the effects of the major components of the ablator on the mechanical and abltion properties were studied, polyoligomeric silesguioxane (POSS) was incorporated into the ablator, and the influence of POSS was also investigated. Finally, a silicone-rubber based ablator with good properties was obtained.The results showed that: the content of carbon fiber was the main factor of the abltion properties of silicone-rubber based ablator. There were three methods to improve the abltion properties of the ablator: increasing the content of carbon fiber, increasing the content of phenyl silicone rubber and reducing the content of silica.The content of nano-silica and carbon fiber played an important role in the mechanical properties of the ablator. Three methods were also mentioned to the improvement of mechanical properties: controlling the content of phenyl silicon rubber in a suitable level, increasing the content of nano-silica and reducing the content of carbon fiber.Carbon fibers with length of 2mm~5mm and treated in air at 400℃showed the best compatible with the silicone rubber matrix, and led to an ablator with good properities. However, all of the flame inhibitors chosen in this paper are not suitable for the silicone rubber system.In this study, the formula of the silicone-rubber based ablator with the best properties is: 50 parts per hundred grams of rubber (phr) phenyl silicone rubber, 30 phr nano-silica, 12 phr carbon fiber (2mm, oxidized at 400℃in air), 1 phr vulcanizator. Linear ablation rate was 0.0545mm/s, mass ablation rate was 0.0538g/s, ceramic ratio is 0.4834, tensile stress was over 3.86MPa, tensile strain was more than 150%.The incorporation of POSS increased the cross-linking density of the ablator. the increment of cross-linking density enhanced the thermal stability of the ablator, and improve the ablation properties, but the mechanical properties the ablators was obviously reduced.